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Human karyogram, with annotated bands and sub-bands. It is a graphical representation of the idealized human diploid karyotype. It shows dark and white regions on G banding. Each row is vertically aligned at centromere level. It shows 22 homologous autosomal chromosome pairs, both the female (XX) and male (XY) versions of the two sex chromosomes, as well as the mitochondrial genome (at bottom left).
Trisomy 21 – Down syndrome, an example of a polysomy at chromosome 21

Polysomy is a condition found in many species, including fungi, plants, insects, and mammals, in which an organism has at least one more chromosome than normal, i.e., there may be three or more copies of the chromosome rather than the expected two copies.[1] Most eukaryotic species are diploid, meaning they have two sets of chromosomes, whereas prokaryotes are haploid, containing a single chromosome in each cell. Aneuploids possess chromosome numbers that are not exact multiples of the haploid number and polysomy is a type of aneuploidy.[2] A karyotype is the set of chromosomes in an organism and the suffix -somy is used to name aneuploid karyotypes. This is not to be confused with the suffix -ploidy, referring to the number of complete sets of chromosomes.

Polysomy is usually caused by non-disjunction (the failure of a pair of homologous chromosomes to separate) during meiosis, but may also be due to a translocation mutation (a chromosome abnormality caused by rearrangement of parts between nonhomologous chromosomes). Polysomy is found in many diseases, including Down syndrome in humans where affected individuals possess three copies (trisomy) of chromosome 21.[3]

Polysomic inheritance occurs during meiosis when chiasmata form between more than two homologous partners, producing multivalent chromosomes.[1] Autopolyploids may show polysomic inheritance of all the linkage groups, and their fertility may be reduced due to unbalanced chromosome numbers in the gametes.[1] In tetrasomic inheritance, four copies of a linkage group rather than two (tetrasomy) assort two-by-two.[1]

Types

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Polysomy types are categorized based on the number of extra chromosomes in each set, noted as a diploid (2n) with an extra chromosome of various numbers. For example, a polysomy with three chromosomes is called a trisomy, a polysomy with four chromosomes is called tetrasomy, etc.:[4]

Number of chromosomes Name Description Examples
3 trisomy Three copies of a chromosome, 2n + 1 Down syndrome (Trisomy 21), Edwards syndrome (Trisomy 18), or Patau syndrome (Trisomy 13)[3]
4 tetrasomy Four copies of a chromosome, 2n + 2 Tetrasomy 9p, Tetrasomy 18p[5]
5 pentasomy Five copies of a chromosome, 2n + 3 Pentasomy X (XXXXX or 49, XXXXX)[6]
6 hexasomy Six copies of a chromosome, 2n + 4 Mosaic hexasomy 21 or partial hexasomy 15[7]
7 heptasomy Seven copies of a chromosome, 2n + 5 Heptasomy 21 in acute myeloid leukemia[8]
8 octosomy Eight copies of a chromosome, 2n + 6 Octosomy in sturgeon fish (Acipenser baerii, A. persicus, A. sinensis, and A. transmontanus)[9]
9 nonasomy Nine copies of a chromosome, 2n + 7 Nonasomy in congenital skeletal polydystrophy[10]
10 decasomy Ten copies of a chromosome, 2n + 8 decasomy 8 in histolytic carcinoma[11]

In mammals

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In canines

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Trisomy 13

Polysomy plays a role in canine leukemia, hemangiopericytomas, and thyroid tumors.[12] Abnormalities of chromosome 13 have been observed in canine osteoid chondrosarcoma and lymphosarcoma.[13] Trisomy 13 in dogs with lymphosarcoma show a longer duration of first remission (medicine) and survival, responding well to treatments with chemotherapeutic agents.[14] Polysomy of chromosome 13 (Polysomy 13) is significant in the development of prostate cancer and is often caused by centric fusions.[12] Since canine chromosome 13 is similar to human chromosome 8q, research could provide insight to treatment for prostate cancer in humans.[15] Polysomy of chromosomes 1, 2, 4, 5, and 25 are also frequently involved in canine tumors.[16] Chromosome 1 may contain a gene responsible for tumor development and lead to changes in the karyotype, including fusion of the centromere, or centric fusions.[16] Aneuploidy due to nondisjunction is a common feature in tumor cells.[17]

In humans

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Sex chromosomes

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Some of the most frequent genetic disorders are abnormalities of sex chromosomes, but polysomies rarely occur.[18] 49,XXXXY chromosome polysomy occurs every 1 in 85,000 newborn males.[19] The incidence of other X polysomies (48,XXXX, 48,XXXY, 48,XXYY) is more rare than 49,XXXXY.[20] Polysomy Y (47,XYY; 48,XYYY; 48,XXYY; 49,XXYYY) occurs in 1 out of 975 males and may cause psychiatric, social, and somatic abnormalities.[21] Polysomy X may cause mental and developmental retardation and physical malformation. Klinefelter syndrome is an example of human polysomy X with the karyotype 47, XXY. X chromosome polysomies can be inherited from either a single maternal (49, X polysomies) or paternal (48, X polysomies) X chromosome.[18] Polysomy of sex chromosomes is caused by successive nondisjunctions in meiosis I and II.[6]

Karyotype of Polysomy Y (XYY)
example of Polysomy X (47,XXY, Klinefelter syndrome)
Effects of Polysomy X as seen in Klinefelter syndrome

Chromosome 7

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CFTR gene on chromosome 7

In squamous cell carcinoma, a protein from the epidermal growth factor receptor (EGFR) gene is often overexpressed in conjunction with polysomy of chromosome 7, so chromosome 7 can be used to predict the presence of EGFR in squamous cell carcinoma.[22] In colorectal cancer, EGFR expression is decreased with polysomy 7, which makes polysomy 7 easier to detect and could be used to prevent patients from having unnecessary cancer treatment.[23]

Chromosome 8

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AML-M2 associated with chromosome 8 abnormality

Tetrasomy and hexasomy 8 are rare compared to trisomy 8, which is the most common karyotypic finding in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS).[24] AML, MDS, or myeloproliferative disorder (MPD) with a high incidence of secondary diseases and a six-month survival rate are associated with a polysomy 8 syndrome.[25]

Chromosome 17

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Overexpression of the HER2/neu gene on chromosome 17 and some type of polysomy has been reported in 8-68% of breast carcinomas.[26] If theHER-2/neu gene does not amplify in the case of polysomy, proteins may be overexpressed and could lead to tumerogenesis.[27] Polysomy 17 may complicate the interpretation of HER2 testing results in cancer patients. Chromosome 17 polysomy may not be present when the centromere is amplified, so it was later discovered that polysomy 17 is rare. This was discovered using array comparative genomic hybridization, a DNA-based alternative for clinical evaluation of HER2 gene copy number.[28]

Trisomy 21

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Nuchal edema in Down Syndrome Dr. W. Moroder

Trisomy 21 is a form of Down syndrome that occurs when there is an extra copy of chromosome 21. The result is a genetic condition in which a person has 47 chromosomes instead of the usual 46. During egg or sperm development the 21st chromosome does not separate during either the egg or sperm development. The result is a cell that has 24 chromosomes. This extra chromosome may cause problems with the manner in which the body and brain develop.[29]

Tetrasomy 9p

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Tetrasomy 9p is a rare condition in which people have a small extra chromosome that contains two copies of part of chromosome 9, in addition to having two normal chromosome 9's as well. This condition may be diagnosed by analyzing a person's blood sample since 9p is found in high concentrations in the blood. Ultrasound is another tool that may be utilized to identify tetrasomy 9p in infants prior to birth. Prenatal ultrasound may reveal several common characteristics including: growth restriction, ventriculomegaly, cleft lip or palate, and renal anomalies.[30]

Tetrasomy 18p

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Main article: Tetrasomy 18p

Tetrasomy 18p occurs when the short arm of the 18th chromosome appears four times, rather than twice, in the cells of the body. It is considered to be a rare disease and usually is not inherited. The mechanism of 18p formation appears to be the result of two independent events: centromeric misdivision and nondisjunction.[31] Characteristic features of tetrasomy 18p include, but are not limited to: growth retardation, scoliosis, abnormal brain MRI, developmental delays, and strabismus.[31]

In insects

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Germ line polysomy in the grasshopper

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Karyotype showing chromosomes 1–22 are grouped A-G

Germ line cells develop into eggs and sperm and the associated inherited material can be passed down to future generations.[32] As shown in the associated karyotype image, chromosomes 1–22 are grouped A-G. A population of male grasshoppers (Chorthippus binotatus) from the Sierra Nevada (Spain) are polysomic mosaics (coming from cells of two genetically different types) possessing an extra E group chromosome(chromosomes 16, 17 & 18) in their testicles.[33] Parents that exhibited polysomy did not pass the E chromosome abnormality to any of the offspring, so this is not something that is passed down to future generations.[33] Male grasshoppers (Atractomorpha similis) from Australia carry between one and ten extra copies of chromosome A9, with one being the most common in natural populations.[34] Most polysomic males produce normal sperm. However, polysomy can be transmissible through both the male and female parents through nondisjunction.[34]

Heterochromatic polysomy in the cricket

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Heterochromatin contains a small number of genes and densely staining nodules in or along chromosomes.[35] The mole cricket chromosome number varies between 19 and 23 chromosomes depending on the part of the world in which they are located, including Jerusalem, Palestine, and Europe.[36] Heterochromic polysomy is seen in mole crickets with 23 chromosomes and may be a factor contributing to their evolution, specifically within the species Gryllotalpa gryllotalpa, along with various living environments and mating systems.[36][37]

X-chromosome polysomy in the fruit fly

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In the fruit fly, Drosophila, one X chromosome in the male is almost the same as two X chromosomes in the female in terms of the gene product produced.[38] Despite this, metafemales, or females having three X chromosomes, are unlikely to survive.[38] It is possible that the extra X chromosome decreases gene expression and could explain why the metafemales rarely survive this X-chromosome polysomy.[38]

In plants

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A karyotype rearrangement of individual chromosomes takes place when polysomy in plants is observed. The mechanism of this type of rearrangement is "non-disjunction, mis-segregation in diploids or polyploids; mis-segregation from multivalents in interchange heterozygotes."[39] Incidences of polysomy have been identified in many species of plants, including:

Brosen flower nn1, Brassica rapa

In fungi

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S. cerevisiae under DIC microscopy

Few fungi have been researched so far, possibly due to the low number of chromosomes in fungi, as determined by pulsed field gel electrophoresis.[46] Polysomy of Chromosome 13 has been observed in the Flor strains of the yeast species Saccharomyces cerevisiae. Chromosome 13 contains loci, specifically the ADH2 and ADH3 loci, which encode for the isozymes of alcohol dehydrogenase. These isozymes play a primary role in the biological aging of wines via ethanol oxidative utilization.[47] Polysomy of Chromosome 13 is promoted when there is disruption of the yeast RNA1 gene with LEU2 sequences.[48]

Diagnostic tools

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FISH (Fluorescent In Situ Hybridization)

Fluorescent in situ hybridization

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Fluorescence in situ hybridization (FISH) is a cytogenetic technique that has proven to be useful in the diagnosis of patients with polysomy.[49] Conventional cytogenetics and fluorescence in situ hybridization (FISH) have been used to detect various polysomies, including the most common autosomies (trisomy 13, 18, 21) as well as polysomy X and Y.[50] Testing for chromosomal aneuploidy with Fluorescence in situ hybridization may increase the sensitivity of cytology and improve the accuracy of cancer diagnosis.[51] The Cervical Cancer, TERC, Fluorescence in situ hybridization test, detects amplification of the human telomerase RNA component (TERC) gene and/or polysomy of chromosome 3.[52]

Spectral karyotyping

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Spectral karyotyping (SKY) looks at the entire karyotype by using fluorescent labels and assigning a particular color to each chromosome. SKY is usually performed after conventional cytogenic techniques have already detected an abnormal chromosome. FISH analysis is then used to confirm the identity of the chromosome.[50]

Giemsa banding (G-banded karyotyping)

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Karyotypes are commonly analyzed using Giemsa banding (G-banded karyotyping). Each chromosome shows unique light and dark bands after they are denatured with trypsin and polysomies can be detected by counting the stained chromosomes. Several cells have to be analysed to detect mosaicism.[53]

Microarray analysis

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Submicroscopic chromosomal abnormalities that are too small to be detected via other means of karyotyping, may be identified by chromosomal microarray analysis.[54] There are several existing microarray techniques that may be utilized during the prenatal diagnosis phase, and these include SNP arrays and comparative genomic hybridization (CGH).[55] CGH is a DNA-based diagnostic tool that has been used to detect polysomy 17 in breast cancer.[27] CGH was first used in 1992 by Kallionemi at UC San Francisco.[56] When used in conjunction with ultrasound findings, microarray analysis may be instrumental in the clinical diagnosis of chromosomal abnormalities.

Prenatal diagnostic tests

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Prenatal and other diagnostic techniques such as immunocytochemistry (ICC) evaluation are usually followed by FISH or Polymerase Chain Reaction to detect chromosomal aneuploidies. Maternal blood sampling for fetal cells, often used to identify risk of trisomies 18 or 21, poses less risk as compared to amniocentesis and chorionic villous sampling (CVS).[57] Chorionic villus sampling utilizes placental tissue to give information about fetal chromosome status and has been used since the 1970s.[58] In addition to CVS, amniocentesis can be used to obtain fetal karyotype by examining fetal cells in amniotic fluid. It was first performed in 1952 and became standard practice in the 1970s.[59] The odds of having a child with polysomy increases as the age of the mother increases, so pregnant women over the age of 35 are tested.[60]

Restriction fragment length polymorphism (RFLP) analysis

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RFLPs can be used to determine the origin and mechanism involved with Polysomy X and other chromosome heteromorphisms or chromosomes that differ in size, shape, or staining properties. Restriction enzymes cut DNA at a specific site and the DNA fragments that are left are called restriction fragment length polymorphisms, or RFLPs.[61] RFLP also aids in the identification of the Huntingtin (HTT) gene which is predictive of an adult-onset autosomal disorder called Huntington's disease (HD). Mutations in chromosome 4 are able to be visualized when RFLP is used in conjunction with Southern blot analysis.[62]

Flow cytometry

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Human lymphocyte cultures may be analyzed by flow cytometry to assess chromosomal abnormalities, such as polyploidy, hypodiploidy, and hyperdiploidy.[63] Flow cytometers have the ability to analyze thousands of cells each second and are commonly used to isolate specific cell populations.

See also

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References

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Further reading

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Revisions and contributorsEdit on WikipediaRead on Wikipedia

Polysomy

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from Grokipedia
Polysomy is a chromosomal condition characterized by the presence of extra copies of one or more chromosomes in a cell, resulting in a number that exceeds the normal diploid complement but is not a multiple of the haploid set. As a specific form of aneuploidy, polysomy typically arises from nondisjunction events during meiosis or mitosis, where chromosomes fail to separate properly, leading to gametes or daughter cells with supernumerary chromosomes. Common subtypes include trisomy (three copies of a chromosome, denoted as 2N+1) and tetrasomy (four copies, denoted as 2N+2), though higher-order polysomies such as pentasomy or hexasomy also occur. In humans, polysomy is associated with several congenital disorders due to gene dosage imbalances from the extra chromosomal material. For instance, Down syndrome results from trisomy 21, where individuals have three copies of chromosome 21, leading to intellectual disability, characteristic facial features, and increased risk of congenital heart defects. Similarly, Klinefelter syndrome involves an extra X chromosome in males (47,XXY karyotype), causing hypogonadism, infertility, and taller stature. Less common examples include tetrasomy 9p syndrome and various sex chromosome polysomies like 48,XXXY or 49,XXXXY, which present with developmental delays, physical anomalies, and endocrine issues. Beyond congenital conditions, polysomy is prevalent in , where it contributes to genomic instability and tumor progression in cancers such as (e.g., apparent polysomy 17) and leukemias (e.g., 12). In these cases, extra chromosome copies often amplify oncogenes or disrupt regulatory pathways, and detection via () helps assess prognosis and treatment response. Polysomy also manifests across diverse species, including fungi, , , and other mammals, where it can influence evolutionary or hybrid vigor in polyploid contexts. In autopolyploid , for example, polysomic inheritance—where multiple homologous chromosomes segregate randomly—allows for greater but complicates breeding and transmission. Overall, while often deleterious in diploids due to proteotoxic stress and developmental disruptions, polysomy's effects vary by , involved, and genetic background.

Definition and Classification

Definition

Polysomy is a chromosomal abnormality characterized by the presence of three or more copies of one or more specific in the cells of an , rather than the typical diploid complement of two copies per chromosome pair. This condition represents a type of , where the total chromosome number deviates from the normal euploid state, but unlike —which involves duplication of entire chromosome sets—polysomy affects only individual or chromosome arms. The term encompasses various degrees of multiplicity, such as (three copies, denoted as 2N+1), tetrasomy (four copies, 2N+2), and higher orders like pentasomy. For instance, , known as in humans, results from an extra copy of and leads to characteristic developmental and physical features. These extra chromosomes often arise from errors in , such as during or , leading to imbalances in that can disrupt normal cellular function and organismal development. In polyploid organisms, particularly in and fungi, polysomy can also describe inheritance patterns where multiple homologous chromosomes (more than two) pair and segregate randomly during , resulting in polysomic as opposed to disomic inheritance seen in diploids. This multivalent pairing complicates genetic transmission and can contribute to or instability in polyploid . Autopolyploids, derived from within-species genome duplication, frequently exhibit polysomic for many loci, while allopolyploids may show a mix of polysomic and disomic patterns depending on homology between subgenomes.

Terminology and Types

Polysomy refers to the genomic condition in which a cell or possesses more than the normal diploid number (two copies) of one or more specific , resulting in three or more copies of those . This abnormality is a subtype of , specifically hyperploidy, and contrasts with , which involves duplication of entire chromosome sets rather than individual . The term "polysomy" derives from the Greek "poly-" meaning many and "-somy" relating to , emphasizing the multiplicity of copies beyond the euploid state. In cytogenetic nomenclature, polysomy is often denoted by specifying the chromosome number and copy count, such as "" for three copies of 21. Types of polysomy are primarily classified based on the number of chromosome copies involved, ranging from the relatively common to rarer higher-order forms like pentasomy or hexasomy. , the most prevalent type, occurs when there are three copies of a , leading to conditions such as (trisomy 21), Edwards syndrome (trisomy 18), and (trisomy 13) in humans. Tetrasomy involves four copies and is less frequent, often arising from events; examples include tetrasomy 18p, which causes developmental delays, , and characteristic facial features due to an extra of the short arm of 18. Higher ploidy levels, such as pentasomy (five copies, e.g., 49,XXXXX in polysomy), are exceedingly rare and typically associated with severe congenital anomalies and reduced viability. Polysomy can also be categorized as full or partial depending on whether the entire or only a segment is duplicated. Full polysomy affects the whole , as in the examples above, while partial polysomy results from duplications or isochromosomes involving chromosome arms, such as partial 9p observed in certain syndromes. In non-human organisms, polysomy manifests similarly but may confer adaptive advantages in plants (e.g., extra copies enhancing for stress resistance) or occur mosaically in and fungi. Detection typically involves karyotyping, (FISH), or array comparative genomic hybridization (aCGH), with polysomy 7, 17, and 3 frequently identified in cancer as markers of genomic instability.

Etiology and Mechanisms

Genetic Causes

Polysomy arises primarily from errors in chromosome segregation during , leading to s or cells with extra copies of one or more s. The most common genetic mechanism is , where homologous chromosomes or fail to separate properly during or . In I, of homologous chromosomes results in s with two copies of a instead of one, and upon fertilization with a normal , this produces a trisomic exhibiting polysomy for that . Similarly, in II or can generate extra chromatids that become whole chromosomes, contributing to polysomy in somatic cells or offspring. This process is frequently linked to defects in -microtubule attachments and centromeric cohesion. Weakened cohesion, particularly in aging oocytes due to progressive loss of cohesin proteins like Rec8 and SMC1β, increases the likelihood of premature separation of or merotelic attachments, where a binds microtubules from both spindle poles. Such errors are exacerbated in human females, where oocytes remain arrested in I for decades, leading to a maternal age effect; the incidence of , including polysomy, rises sharply after age 35, with maternal I errors accounting for over 90% of cases in trisomies like ( 21). In addition to , other genetic factors include mutations affecting spindle assembly checkpoint (SAC) proteins, such as MAD2 or BUBR1, which fail to halt until proper attachments are ensured, allowing lagging to missegregate. Hyperstable kinetochore attachments or extra centrosomes can also promote multipolar spindles, further driving gain in polysomic states. These mechanisms are conserved across eukaryotes but vary in ; for instance, in , polysomy often stems from unreduced (2n) gametes formed via meiotic restitution, where spindle alterations or failures omit segregation steps, leading to extra copies upon fertilization. Seminal studies highlight that such errors underlie at least 5-20% of conceptions and are key drivers of evolutionary variation in polyploid .

Environmental and Developmental Factors

Environmental and developmental factors play a significant role in the of polysomy by disrupting segregation during or , leading to and extra copies. These factors often interact with genetic predispositions, increasing the likelihood of aneuploid gametes or cells across various organisms. In animals, is a primary developmental risk, as aging s accumulate recombination errors and spindle assembly defects, elevating rates—particularly for prone to polysomy like 21 in humans, where the risk rises exponentially after age 35. Similarly, disruptions during fetal development, such as altered recombination patterns, can predispose cohorts of s to segregation errors in adulthood. In humans and other mammals, environmental exposures exacerbate these risks. Endocrine disruptors like (BPA) induce spindle aberrations and meiotic delays in oocytes, correlating with higher in exposed populations; for instance, BPA in follicular fluid is linked to reduced oocyte maturity and increased chromosomal abnormalities. and smokeless tobacco use, independent of age, heighten meiosis II nondisjunction for by reducing recombination frequency, with odds ratios up to 2.77 in affected families. and pesticide exposure, such as trichlorfon, further promote spindle disruptions and sperm or oocytes in model animals like mice and fish. In , developmental processes like produce unreduced (2n) , often resulting in polysomic progeny upon fertilization, especially in hybrids where univalent fail to pair properly. Environmental stresses, including extreme (e.g., above 36°C in roses or cold below 5°C in ), trigger spindle defects and failure, boosting 2n gamete formation by up to 50% and leading to aneuploid sectors. , an intercellular chromosome transfer during , is enhanced by high or moisture stress in species like and , generating polysomic and contributing to . For fungi, developmental cell cycle checkpoints are sensitive to environmental cues, where nutrient limitation or osmotic stress induces mitotic errors, yielding transient as an adaptive response; for example, in , such stresses promote chromosome missegregation to explore under adverse conditions. Overall, these factors underscore polysomy's role in both and , with quantitative impacts varying by organism—e.g., stress-induced rates can reach 10-20% in stressed meiocytes versus baseline levels below 1%.

Occurrence in Animals

In Mammals

In mammals, polysomy, characterized by the presence of extra chromosomes beyond the normal diploid set, is predominantly deleterious and frequently results in embryonic or fetal lethality due to imbalances disrupting development. Autosomal polysomies, such as , occur in a significant proportion of early embryos across , often arising from meiotic errors, but viable live births are exceedingly rare outside of humans. In human pregnancies, affects approximately 35-50% of embryos, with (Down syndrome) being the most common surviving form, occurring in about 1 in 640 live births and associated with , congenital heart defects, and other anomalies. 18 and 13 also reach live birth in roughly 1 in 3,336 and 1 in 6,967 cases, respectively, but typically lead to severe developmental issues and high postnatal mortality. In non-human mammals, autosomal are even less tolerated; for instance, in , they contribute to over 50% of pregnancy losses before day 55, with affecting chromosomes syntenic to human 3, 4, and 20, often alongside triploidy. Similarly, in , SNP array analysis of over 779,000 juveniles revealed autosomal in only 0.017% of cases, primarily maternal in origin and concentrated on smaller chromosomes like BTA 27, with affected individuals showing reduced viability—many dying within months and none surviving long-term on certain chromosomes. Sex chromosome polysomies are generally better tolerated in mammals due to dosage compensation mechanisms like , allowing survival into adulthood despite reproductive impairments. The XXY , analogous to human , has been documented in various species, including domestic cats (Felis catus), dogs (Canis familiaris), and notably a (Panthera tigris altaica), where it manifests as , small testes, and , with scarce seminiferous tubules observed histologically. These cases often stem from during and highlight conserved phenotypic effects across mammals, such as reduced testosterone and altered secondary sexual characteristics. XXX and XYY variants are rarer but reported in mice and , sometimes as mosaics, with milder impacts on viability but consistent fertility issues. A notable exception to the of polysomy in mammals is the presence of supernumerary B chromosomes, which are dispensable, non-homologous extra chromosomes occurring naturally in populations without disrupting essential functions. These have been identified in approximately 85 mammalian (about 1.94% of karyotyped ), predominantly in of the family , such as the yellow-necked mouse (Apodemus flavicollis) and Korean field mouse (Apodemus peninsulae), where individuals may carry 1-30 Bs with population frequencies ranging from 0 to 100%. B chromosomes vary in morphology (e.g., microchromosomes in possums like Petauroides volans or acrocentrics in foxes like Vulpes vulpes) and can influence traits including body size, behavior, and recombination rates, often through selfish drive mechanisms that bias transmission. Molecular analyses confirm they contain protein-coding genes in like the (Capreolus pygargus), challenging views of Bs as inert and suggesting adaptive roles in some contexts. Unlike pathological polysomies, Bs persist across generations and geographic ranges, as seen in European populations of A. flavicollis.

In Insects

Polysomy, a form of involving extra copies of specific chromosomes, has been extensively studied in , particularly in the Drosophila melanogaster. In this species, whole-chromosome aneuploidies such as trisomies lead to reduced organismal viability, primarily due to imbalances that disrupt and cellular function. Segmental trisomies, where portions of chromosomes are duplicated, show an inverse with fertility and viability, with larger duplicated segments causing more severe impairments. Mechanisms underlying polysomy in include nondisjunction and anaphase bridges during , which are exacerbated in parthenogenetic reproduction. In facultative parthenogenetic species like mercatorum, aneuploidy rates are higher in parthenogenetically produced offspring (up to 10.3% of cells) compared to sexually reproduced ones (3.6%), yet no overt tissue dysplasia is observed, suggesting tolerance mechanisms. buffering acts as a key compensatory response; for instance, genes in hemizygous (single-copy) regions from deficiencies are expressed at approximately 64% of wild-type levels rather than the expected 50%, mitigating dosage effects across much of the . The fourth exhibits particularly robust compensation mediated by the Painting of Fourth (POF) protein, allowing viability in haplo-4 flies that would otherwise be lethal. Pathophysiological effects of polysomy in manifest as cellular stress responses, including proteotoxic stress, production, and mitochondrial dysfunction, often triggering JNK-dependent or to eliminate aneuploid cells. When is suppressed, aneuploid cells can drive tumor-like overgrowth and invasiveness, with gains in autosomes promoting proliferation via the JNK and Wingless pathways. In parthenogenetic contexts, polysomy contributes to intra-individual genomic variability without apparent developmental abnormalities, potentially enhancing adaptability, though larger-scale aneuploidies (e.g., ~3% of the as single copies) are lethal. Cell further maintains tissue integrity by purging segmental aneuploid cells based on ribosomal protein imbalances. Beyond , aneuploid and polyploid cellular heterogeneity has been noted in cell cultures of dipteran insects, indicating that polysomy-like states may arise naturally during development or under stress, though specific polysomy studies remain limited to model systems. Induced polysomies via agents like colcemid in D. melanogaster produce triploid at frequencies up to 18%, highlighting the role of mitotic errors in generating such conditions experimentally.

Occurrence in Plants and Fungi

In Plants

In plants, polysomy refers to the presence of extra copies of one or more chromosomes beyond the normal diploid complement, such as trisomy (2n+1) or tetrasomy (2n+2), representing a form of aneuploidy. Unlike animals, plants often tolerate polysomy better due to their flexible genome architecture and frequent polyploidy, which provides genetic buffering against imbalance. This tolerance allows polysomic plants to survive and propagate, though typically with reduced vigor and fertility. Polysomy in primarily arises through meiotic , where chromosomes fail to segregate properly, producing gametes with extra chromosomes that fertilize to form aneuploid zygotes. It can also result from crosses involving polyploids, such as triploids to diploids, generating viable trisomic progeny. Early seminal work by Albert F. Blakeslee in the 1920s identified 12 distinct trisomic types in (jimsonweed), each corresponding to an extra copy of one of its 12 chromosomes, demonstrating chromosome-specific morphological alterations like enlarged organs or distorted growth. These trisomics became a foundational model for studying dosage effects, as homozygous revealed direct phenotypic impacts from imbalance. In model and crop plants, polysomy induces diverse, chromosome-specific phenotypes often linked to changes. For instance, in Arabidopsis thaliana, of chromosome 1 results in smaller rosettes and reduced stem diameter, while of chromosome 5 promotes triple branching and alters axillary development; these effects are additive in double and persist epigenetically in euploid . Transcriptomic analyses show upregulated expression from the extra chromosome, with partial dosage compensation and secondary imbalances in other genes, underscoring polysomy's role in disrupting regulatory networks. In crops like (Triticum aestivum), persistent whole-chromosome , including polysomy, occurs in 20–100% of synthetic allohexaploid lines across generations, particularly involving B-genome chromosomes (e.g., extra 1B or 5B), leading to pollen sterility and reduced seed set but enabling adaptive variation. Polysomy has practical utility in and breeding, serving as a tool for and alien transfer. In and , trisomics facilitate locating genes by analyzing segregation ratios, while chromosome substitution via polysomic intermediates introduces beneficial traits from wild relatives. Examples include trisomics in (Solanum lycopersicum) for fruit quality genes and in (Hordeum vulgare) for yield-related loci, highlighting polysomy's contributions to crop improvement despite its fitness costs. Overall, while deleterious, polysomy exemplifies ' genomic plasticity, influencing through occasional fixation in polyploid lineages.

In Fungi

Polysomy, characterized by the presence of more than two copies of a specific , represents a key form of in fungi and contributes to their genomic plasticity, particularly in response to environmental stresses such as drugs or nutrient limitations. Unlike balanced , which involves complete sets of extra chromosomes, polysomy often arises from errors in chromosome segregation during or parasexual cycles, leading to transient or stable extra copies of individual chromosomes. This phenomenon is prevalent across fungal species, from yeasts to filamentous pathogens, where it enables rapid without requiring extensive sequence mutations. Fungi tolerate polysomy relatively well compared to higher eukaryotes due to their frequent haploid life stages and lack of stringent meiotic checkpoints, allowing aneuploid cells to propagate and evolve. In the model yeast , polysomy occurs naturally in wild, clinical, and industrial isolates, with up to 36% of diploid strains exhibiting after extended culturing. For example, genetic disruptions in the RNA1 gene, involved in processing, specifically promote polysomy of chromosome XIII by interfering with mitotic fidelity, resulting in viable cells with three or more copies. of chromosome III has been linked to enhanced tolerance in industrial strains, while extra copies of chromosomes II, VII, or VIII confer resistance to copper stress, illustrating how polysomy amplifies for adaptive traits. These events often stem from during and are detected through whole-genome sequencing or array in laboratory-evolved populations. Among pathogenic fungi, frequently displays polysomy, especially in clinical isolates exposed to , with approximately 5% carrying supernumerary chromosomes and higher rates in drug-resistant populations. of smaller chromosomes (4 through 7) is most common, driven by selection, and increases expression of resistance genes like ERG11 on , enabling survival at elevated concentrations. Similarly, of chromosome 7 upregulates NRG1, promoting gastrointestinal colonization and filamentation. In , disomy of chromosomes 1 or 4 arises under stress, providing to other antifungals via effects. Filamentous species like also acquire polysomies during azole exposure, with extra copies of chromosomes containing genes enhancing resistance. In Ashbya gossypii, a pathogen, aneuploid nuclei with polysomic chromosomes coexist in multinucleate hyphae, supporting filamentous growth. Overall, these examples highlight polysomy's role in fungal and adaptation, often at the cost of reduced fitness in non-stressful conditions due to proteotoxic imbalances from imbalanced .

Pathophysiological Effects

Phenotypic Consequences

Polysomy, characterized by the presence of extra copies of one or more chromosomes, disrupts the balanced gene dosage essential for normal development and function, leading to a range of phenotypic abnormalities across organisms. In humans, autosomal polysomies such as trisomies 13, 18, and 21 typically result in severe congenital malformations, growth retardation, and intellectual disabilities, with most cases causing embryonic lethality or spontaneous abortion early in gestation. For instance, trisomy 21 (Down syndrome) manifests in over 70 distinct phenotypes, including hypotonia, characteristic facial features, atrioventricular septal defects in about 40-50% of cases, and increased susceptibility to autoimmune disorders, as well as to leukemia and Alzheimer's disease, with affected individuals showing a 1.5-fold increase in trisomic gene expression that triggers genome-wide deregulation of pathways such as autophagy and innate immunity. Trisomy 18 (Edwards syndrome) survivors exhibit clenched fists, rocker-bottom feet, and profound developmental delays, with survival beyond the first year in only about 5-10% of cases due to respiratory and cardiac complications. Sex chromosome polysomies in humans often have subtler but still significant effects, primarily impacting reproductive, cognitive, and physical traits, as partial dosage compensation via mitigates some imbalances. (47,XXY) affects approximately 1 in 500-1,000 males and is associated with tall stature, , reduced testosterone levels leading to in nearly 100% of cases, and a higher incidence of learning disabilities and social challenges, with diagnosis frequently occurring post-puberty due to these endocrine disruptions. Triple X syndrome (47,XXX) in females, occurring in about 1 in 1,000 births, correlates with increased height, premature ovarian failure, and mild cognitive impairments such as delayed speech development, though many individuals remain undiagnosed due to less severe manifestations. Similarly, in males leads to taller stature and potential behavioral issues like impulsivity, but fertility is typically preserved and intellectual function is often normal, highlighting the variable expressivity influenced by genes. In non-human mammals, polysomy generally imposes greater fitness costs, often resulting in embryonic inviability or reduced viability, though viable models provide insights into human conditions. models of 21, generated via segmental duplication or Robertsonian translocations, recapitulate phenotypes including , impaired learning, and early-onset neurodegeneration linked to overexpression of genes like RCAN1 and . In canines, rare cases of prostate carcinoma with polysomy demonstrate aggressive tumor progression and , underscoring polysomy's role in oncogenesis similar to cancers. Across mammals, sex polysomies like XXY in mice or cattle lead to sterility and , with disrupted due to imbalanced sex-determining , emphasizing the evolutionary intolerance for such imbalances in germ cells. Overall, phenotypic consequences of polysomy stem from proteotoxic stress and altered , where extra s cause stoichiometric imbalances in protein complexes, triggering cellular responses like mitochondrial dysfunction and heightened that exacerbate developmental and pathological outcomes. These effects underscore polysomy's pathophysiological burden, particularly in mammals where often hinges on the specific chromosome involved and compensatory mechanisms.

Role in Disease and Evolution

Polysomy, as a form of involving extra copies of chromosomes or chromosomal segments, plays a significant role in human genetic diseases by disrupting gene dosage balance and leading to developmental abnormalities. In , trisomy 21 results in , characteristic facial features, and increased risk of congenital heart defects and , affecting approximately 1 in 700 live births. Similarly, (47,XXY), a common polysomy in males, is associated with , , taller stature, and elevated risks of metabolic disorders, autoimmune conditions, and , with an incidence of about 1 in 500 to 1,000 newborn males. Higher-degree polysomies, such as 48,XXXY or 49,XXXXY variants, exacerbate these phenotypes, including more severe cognitive impairments and skeletal anomalies, though they are rarer. Y chromosome polysomy (e.g., 47,XYY) is linked to increased mortality from cardiovascular and respiratory diseases, as well as slightly higher cancer incidence, based on cohort studies of affected individuals. In , polysomy contributes to disease progression by fostering genomic instability and tumor heterogeneity, enabling cancer cells to evade therapies and metastasize. For instance, 17 polysomy in complicates HER2 testing and correlates with aggressive tumor behavior and poorer , often co-occurring with amplifications of oncogenes like ERBB2. Polysomy 8 in myeloid malignancies defines a subset with dismal outcomes, characterized by multilineage and rapid progression to . More broadly, , including polysomic states, drives "macroevolutionary" changes in tumors through chromosomal instability (CIN), promoting and , as evidenced in analyses of over 6,800 tumors across 32 cancer types where CIN-related mutations affected segregation fidelity. This instability creates a vicious cycle, where initial induces further chromosomal errors, amplifying expression and suppressing tumor suppressors. Beyond pathology, polysomy facilitates evolutionary in various organisms by generating rapid under stress, particularly in and unicellular eukaryotes where tolerance to imbalance is higher than in animals. In , disomic strains (extra chromosome copies) exhibit initial fitness costs but evolve compensatory s, restoring growth rates to near wild-type levels within hundreds of generations and increasing mutation rates up to eightfold on duplicated chromosomes, thus accelerating to limitation or shifts. In like , triploid intermediates produce aneuploid progeny with variable karyotypes, promoting , polyploid formation, and allelic biases that enhance and environmental resilience, as seen in recombinant lines where ploidy-dependent selection favors certain loci. Such mechanisms underscore polysomy's dual nature: deleterious in stable environments but potentially advantageous in dynamic ones, contributing to in polyploid-rich lineages like .

Diagnostic Methods

Cytogenetic Techniques

Cytogenetic techniques are essential for detecting polysomy, a form of characterized by the presence of extra copies beyond the normal diploid set, by visualizing and enumerating chromosomes in cell preparations. These methods, which range from classical microscopic analysis to fluorescence-based hybridization, enable the identification of numerical abnormalities in both constitutional and somatic contexts, such as prenatal diagnostics and cancer . While karyotyping provides a genome-wide view, targeted approaches like (FISH) offer rapid, specific detection, often complementing each other for comprehensive assessment. Conventional karyotyping, also known as analysis, remains the gold standard for detecting polysomy through direct visualization of the entire complement. This technique involves culturing cells (e.g., from blood, , or ) to obtain spreads, followed by staining with to produce characteristic light and dark bands for identification and counting. It reliably identifies extra chromosomes indicative of polysomy, such as trisomy 21 in or multiple copies in polysomy studies, with analysis typically requiring examination of 20 cells, or up to 50 for mosaicism detection. However, its resolution is limited to abnormalities larger than 5-10 megabases, and it demands for arrest, making it unsuitable for non-dividing samples. Fluorescence in situ hybridization (FISH) is a widely adopted molecular cytogenetic method for precise polysomy detection, particularly in interphase nuclei where metaphases are unavailable. It employs fluorescently labeled DNA probes that hybridize to specific chromosomal regions, such as centromeres (e.g., CEP7 for chromosome 7), allowing enumeration of copy numbers under a fluorescence microscope—typically showing three or more signals per nucleus for trisomy or higher polysomy. In clinical applications, like prenatal diagnosis, FISH targets common aneuploidies (chromosomes 13, 18, 21, X, Y) with near-100% sensitivity and specificity in validated studies, enabling results within 24-48 hours from samples like chorionic villi. For somatic polysomy in cancers, such as cholangiocarcinoma, locus-specific or centromeric probes distinguish true chromosomal gains from gene amplification, correlating extra copies (e.g., >8% cells with chromosome 7 polysomy) with poor prognosis. Limitations include its targeted nature, requiring prior suspicion of the affected chromosome, and potential signal overlap in high-polysomy cases. Recent advancements as of 2025 incorporate AI-driven image analysis to automate signal counting and improve detection of low-level mosaicism in FISH, enhancing efficiency in high-throughput settings. Advanced variants like spectral karyotyping (SKY) or multicolor FISH (mFISH) extend cytogenetic analysis by painting each chromosome with unique fluorophore combinations, aiding in the detection of complex polysomies involving rearrangements. These techniques, applied to spreads, facilitate identification of multiple extra chromosomes in heterogeneous populations, such as in tumor cells exhibiting polysomy 12 in . Overall, integrating karyotyping with FISH enhances diagnostic accuracy for polysomy, balancing broad screening with targeted confirmation across diverse biological systems.

Molecular and Imaging Techniques

Molecular techniques for detecting polysomy involve quantifying DNA copy numbers at specific chromosomal loci or genome-wide, enabling precise identification of extra chromosome copies beyond the normal diploid or polyploid state. These methods are widely applied in prenatal diagnostics, cancer research, and evolutionary studies across eukaryotes, including mammals, plants, and fungi. Key approaches include polymerase chain reaction (PCR)-based assays, array-based hybridization, and sequencing technologies, each offering varying resolution and throughput. As of 2025, combined approaches like karyotyping with copy number variation sequencing (CNV-seq) have improved detection rates for submicroscopic variants in prenatal samples. Quantitative fluorescence PCR (QF-PCR) targets short tandem repeats on chromosomes prone to polysomy, such as 13, 18, 21, X, and Y, amplifying them with fluorescent primers to assess copy number via peak ratios in electropherograms. This technique achieves high sensitivity (95.65%) and specificity (99.97%) for common aneuploidies, making it cost-effective and automatable for rapid screening, though it is limited to predefined targets and cannot detect structural variants or mosaicism below 20-30%. Multiplex ligation-dependent probe amplification (MLPA) employs multiple probes that ligate only upon matching target sequences, followed by PCR amplification to quantify copy numbers for up to 50 loci simultaneously. It is particularly useful for detecting polysomy in clinical samples like , providing results in 24-48 hours with high accuracy for dosage-sensitive genes, but requires validation for novel variants and misses balanced rearrangements. Array comparative genomic hybridization (aCGH) compares fluorescently labeled test and reference DNA hybridized to arrays, detecting copy number gains or losses at resolutions down to 50-100 kb. Widely adopted for genome-wide polysomy screening in prenatal and contexts, it shows high concordance (approximately 99%) with traditional for detection, though it cannot phase haplotypes or detect low-level mosaicism without single-nucleotide polymorphism (SNP) integration. SNP microarray analysis extends copy number detection by genotyping SNPs across the genome, distinguishing polysomy from uniparental disomy via allele imbalance patterns. It excels in identifying segmental aneuploidies and triploidy with high accuracy (up to 100% in validation studies) for targeted chromosomes in diverse samples, including plant polyploids, but demands reference data and computational tools for interpretation. Next-generation sequencing (NGS), including whole-genome and targeted panels, counts sequencing reads aligned to reference chromosomes to infer copy numbers, often via binomial or z-score models. This method detects polysomy with >99% sensitivity and specificity, even in cell-free DNA for noninvasive prenatal testing, and is adaptable to non-model organisms like insects and fungi through shallow whole-genome sequencing; however, it is costlier and sensitive to sequencing biases or low input DNA. Emerging applications as of 2025 include exome sequencing pipelines that simultaneously detect aneuploidy and single-nucleotide variants, streamlining diagnostics in constitutional cases. Imaging techniques complement molecular methods by visualizing chromosomal abnormalities directly in cells or tissues, facilitating spatial confirmation of polysomy. Advanced variants like multicolor (M-FISH) or spectral karyotyping () employ combinatorial probe sets to paint entire chromosomes in distinct colors, enabling whole-genome visualization of polysomy in spreads. These techniques, with resolutions down to 1-5 Mb, are seminal for complex in cancer and across eukaryotes, achieving near-100% accuracy for gross imbalances but requiring cell culturing and high-quality spreads. Digital image analysis integrates with software algorithms to quantify signals or DNA content, enhancing detection of low-level polysomy (e.g., 10-20% mosaicism) in cytology samples. In combination with confocal or , it provides three-dimensional mapping, vital for studying polysomy dynamics in dividing cells of diverse organisms, though throughput remains lower than purely molecular assays.

References

  1. https://www.ncbi.nlm.nih.gov/medgen/269463
  2. http://basicgenetics.ansci.cornell.edu/dictionary.html
  3. https://www.biologyonline.com/dictionary/polysomy
  4. https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/polysomy
  5. https://www.ncbi.nlm.nih.gov/books/NBK526016/
  6. https://ghr.nlm.nih.gov/condition/klinefelter-syndrome
  7. https://pubmed.ncbi.nlm.nih.gov/23807776/
  8. https://pmc.ncbi.nlm.nih.gov/articles/PMC6505158/
  9. https://www.ncbi.nlm.nih.gov/books/NBK557691/
  10. https://taylorandfrancis.com/knowledge/Medicine_and_healthcare/Medical_genetics/Polysomy/
  11. https://iastate.pressbooks.pub/cropgenetics/chapter/ploidy-polyploidy-aneuploidy-haploidy-2/
  12. https://www.ncbi.nlm.nih.gov/books/NBK132134/
  13. https://medlineplus.gov/genetics/condition/tetrasomy-18p/
  14. https://www.biologyonline.com/dictionary/tetrasomy
  15. https://rarediseases.org/rare-diseases/chromosome-9-trisomy-9p-multiple-variants/
  16. https://www.nature.com/articles/s41467-019-13669-2
  17. https://pubmed.ncbi.nlm.nih.gov/8504429/
  18. https://pmc.ncbi.nlm.nih.gov/articles/PMC2997176/
  19. https://www.nature.com/scitable/topicpage/chromosomal-abnormalities-aneuploidies-290/
  20. https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.12184
  21. https://pmc.ncbi.nlm.nih.gov/articles/PMC3551553/
  22. https://pmc.ncbi.nlm.nih.gov/articles/PMC8599692/
  23. https://pmc.ncbi.nlm.nih.gov/articles/PMC2604943/
  24. https://www.sciencedirect.com/science/article/pii/S2214662814000103
  25. https://pmc.ncbi.nlm.nih.gov/articles/PMC5656283/
  26. https://www.cdc.gov/birth-defects/data-research/facts-stats/index.html
  27. https://www.pnas.org/doi/10.1073/pnas.2405636121
  28. https://onlinelibrary.wiley.com/doi/full/10.1111/jbg.12902
  29. https://www.researchgate.net/publication/10779807_Klinefelter_syndrome_39_XXY_in_an_adult_Siberian_tiger_Panthera_tigris_altaica
  30. https://pubmed.ncbi.nlm.nih.gov/20308053/
  31. https://pmc.ncbi.nlm.nih.gov/articles/PMC6210394/
  32. https://doi.org/10.1016/j.devcel.2023.12.009
  33. https://doi.org/10.1038/s41437-023-00664-z
  34. https://doi.org/10.1371/journal.pgen.1000465
  35. https://doi.org/10.7554/eLife.61172
  36. https://pubmed.ncbi.nlm.nih.gov/2127179/
  37. https://doi.org/10.1016/0027-5107(82)90171-3
  38. https://pmc.ncbi.nlm.nih.gov/articles/PMC2562519/
  39. https://pmc.ncbi.nlm.nih.gov/articles/PMC2998307/
  40. https://www.pnas.org/doi/pdf/10.1073/pnas.7.5.148
  41. https://www.sciencedirect.com/science/article/abs/pii/S1084952113000220
  42. https://doi.org/10.1534/genetics.110.121079
  43. https://www.pnas.org/doi/10.1073/pnas.1300153110
  44. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/trisomics
  45. https://pmc.ncbi.nlm.nih.gov/articles/PMC1203148/
  46. https://doi.org/10.3389/fgene.2019.00082
  47. https://www.nature.com/articles/s41467-025-58457-3
  48. https://journals.asm.org/doi/10.1128/ec.00060-10
  49. https://pmc.ncbi.nlm.nih.gov/articles/PMC6826469/
  50. https://journals.asm.org/doi/10.1128/spectrum.04339-22
  51. https://pmc.ncbi.nlm.nih.gov/articles/PMC9808507/
  52. https://www.sciencedirect.com/science/article/pii/S2666668523000149
  53. https://pmc.ncbi.nlm.nih.gov/articles/PMC5694684/
  54. https://www.sciencedirect.com/science/chapter/handbook/pii/B9780444632333000245
  55. https://www.sciencedirect.com/science/article/abs/pii/S0165460806002366
  56. https://karger.com/cgr/article/140/2-4/256/62187/Polyploidy-in-Animals-Effects-of-Gene-Expression
  57. https://pubmed.ncbi.nlm.nih.gov/32029743/
  58. https://pubmed.ncbi.nlm.nih.gov/17062147/
  59. https://pubmed.ncbi.nlm.nih.gov/3417301/
  60. https://pubmed.ncbi.nlm.nih.gov/17457613/
  61. https://pubmed.ncbi.nlm.nih.gov/18794552/
  62. https://pubmed.ncbi.nlm.nih.gov/15993266/
  63. https://pubmed.ncbi.nlm.nih.gov/28049655/
  64. https://pubmed.ncbi.nlm.nih.gov/23709119/
  65. https://pmc.ncbi.nlm.nih.gov/articles/PMC1449780/
  66. https://www.ncbi.nlm.nih.gov/books/NBK563293/
  67. https://onlinelibrary.wiley.com/doi/full/10.1002/ajmg.c.30114
  68. https://www.sciencedirect.com/science/article/pii/B978044306901750016X
  69. http://www.nature.com/scitable/topicpage/karyotyping-for-chromosomal-abnormalities-298
  70. https://www.nature.com/articles/s41598-022-11945-8
  71. https://www.medrxiv.org/content/10.1101/2025.03.22.25324455v1
  72. https://www.intechopen.com/online-first/1189628
  73. https://www.sciencedirect.com/science/article/pii/S1044579X06001179
  74. https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2024.1517270/full
  75. https://pmc.ncbi.nlm.nih.gov/articles/PMC3632021/
  76. https://doi.org/10.1177/24726303211021787
  77. https://pmc.ncbi.nlm.nih.gov/articles/PMC12470036/
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