Mendelian traits in humans

Sickle-cell disease is inherited in the autosomal recessive pattern. When both parents have sickle-cell trait (carrier), a child has a 25% chance of sickle-cell disease (red icon), 25% do not carry any sickle-cell alleles (blue icon), and 50% have the heterozygous (carrier) condition.^[1]

Mendelian traits in humans are human traits that are substantially influenced by Mendelian inheritance. Most – if not all – Mendelian traits are also influenced by other genes, the environment, immune responses, and chance. Therefore no trait is purely Mendelian, but many traits are almost entirely Mendelian, including canonical examples, such as those listed below. Purely Mendelian traits are a minority of all traits, since most phenotypic traits exhibit incomplete dominance, codominance, and contributions from many genes. If a trait is genetically influenced, but not well characterized by Mendelian inheritance, it is non-Mendelian.

Examples

Albinism (recessive)^[2]^: 53
Achondroplasia^[2]^: 53
Alkaptonuria^[2]^{: 53, 263}
Ataxia telangiectasia^[2]^: 53
Brachydactyly (shortness of fingers and toes)^[2]^: 53
Cataracts
Colour blindness^[2]^: 53 (monochromatism, dichromatism, anomalous trichromatism, tritanopia, deuteranopia, protanopia)
Duchenne muscular dystrophy^[2]^: 53
Ectrodactyly^[3]
Ehlers–Danlos syndrome^[2]^: 53
Fabry disease^{[citation needed]}
Galactosemia^[2]^: 53
Gaucher's disease^{[citation needed]}
Haemophilia
Hereditary breast–ovarian cancer syndrome^{[citation needed]}
Hereditary nonpolyposis colorectal cancer^{[citation needed]}
HFE hereditary haemochromatosis
Huntington's disease^[2]^: 53
Hypercholesterolemia^[2]^: 53
Krabbe disease^{[citation needed]}
Lactase persistence (dominant) ^[4]
Leber's hereditary optic neuropathy^{[citation needed]}
Lesch–Nyhan syndrome^[2]^: 53
Marfan syndrome^[2]^: 53
Niemann–Pick disease^{[citation needed]}
Phenylketonuria^[2]^: 53
Porphyria^[2]^: 53
Retinoblastoma^{[citation needed]}
Sickle-cell disease^[2]^: 53
Sanfilippo syndrome^{[citation needed]}
Tay–Sachs disease^[2]^: 53
Wet (dominant) or dry (recessive) earwax^[5]

Non-Mendelian traits

Most traits (including all complex traits) are non-Mendelian. Some traits commonly thought of as Mendelian are not, including:

References

^ ^a ^b "Inheritance of Sickle Cell Anaemia". Sickle Cell Society. 13 July 2014. Archived from the original on 2018-03-27. Retrieved 2015-12-29.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q Klug WS, Cummings MR, Spencer CA, Palladino MA (2012). Essentials of Genetics. Pearson. ISBN 978-0-321-80311-5.
^ Sowińska-Seidler A, Socha M, Jamsheer A (February 2014). "Split-hand/foot malformation - molecular cause and implications in genetic counseling". Journal of Applied Genetics. 55 (1): 105–115. doi:10.1007/s13353-013-0178-5. PMC 3909621. PMID 24163146.
^ Hollfelder N, Babiker H, Granehäll L, Schlebusch CM, Jakobsson M (April 2020). "The genetic variation of lactase persistence alleles in northeast Africa". bioRxiv 10.1101/2020.04.23.057356.
^ McDonald JH (16 September 2013). "Earwax". Myths of Human Genetics. Baltimore: Sparky House Publishing.
^ "Non-Mendelian Genetics". Untamed Science. Retrieved 2018-12-10.
^ McDonald, John H. (2011). "Myths of Human Genetics: Tongue Rolling". udel.edu. Retrieved 2025-04-30.

External links

[sicklecellsociety.org-1] "Inheritance of Sickle Cell Anaemia". Sickle Cell Society. 13 July 2014. Archived from the original on 2018-03-27. Retrieved 2015-12-29.

[essentials-2] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q Klug WS, Cummings MR, Spencer CA, Palladino MA (2012). Essentials of Genetics. Pearson. ISBN 978-0-321-80311-5.

[3] Sowińska-Seidler A, Socha M, Jamsheer A (February 2014). "Split-hand/foot malformation - molecular cause and implications in genetic counseling". Journal of Applied Genetics. 55 (1): 105–115. doi:10.1007/s13353-013-0178-5. PMC 3909621. PMID 24163146.

[4] Hollfelder N, Babiker H, Granehäll L, Schlebusch CM, Jakobsson M (April 2020). "The genetic variation of lactase persistence alleles in northeast Africa". bioRxiv 10.1101/2020.04.23.057356.

[5] McDonald JH (16 September 2013). "Earwax". Myths of Human Genetics. Baltimore: Sparky House Publishing.

[6] "Non-Mendelian Genetics". Untamed Science. Retrieved 2018-12-10.

[7] McDonald, John H. (2011). "Myths of Human Genetics: Tongue Rolling". udel.edu. Retrieved 2025-04-30.

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