Ocular albinism type 1 (OA1) is the most common type of ocular albinism, with a prevalence rate of 1:50,000. It is an inheritable classical Mendelian type X-linked recessive disorder wherein the retinal pigment epithelium lacks pigment while hair and skin appear normal. Since it is usually an X-linked disorder, it occurs mostly in males, while females are carriers unless they are homozygous. About 60 missense and nonsense mutations, insertions, and deletions have been identified in Oa1. Mutations in OA1 have been linked to defective glycosylation and thus improper intracellular transportation.

The eponyms of the name "Nettleship–Falls syndrome" are the ophthalmologists Edward Nettleship and Harold Francis Falls.

OA1 is recognized by many different symptoms. Reduced visual acuity is accompanied by involuntary movements of the eye termed as nystagmus. Astigmatism is a condition wherein there occurs significant refractive error. Moreover, ocular albino eyes become crossed, a condition called 'lazy eyes' or strabismus. Since very little pigment is present the iris becomes translucent and reflects light back. It appears green to violet. However, the most important part of the eye, the fovea which is responsible for acute vision, does not develop properly, probably indicating the role of melanin in the development stages of the eye. Some affected individuals may also develop photophobia/photodysphoria. All these symptoms are due to lack of pigmentation of the retina. Moreover, in an ocular albino eye, nerves from back of the eye to the brain may not follow the usual pattern of routing. In an ocular albino eye, more nerves cross from back of the eye to the opposite side of the brain instead of going to both sides of the brain as in a normal eye. An ocular albino eye appears blueish pink in color with no pigmentation at all unlike a normal eye. Carrier women have regions of hypo- and hyper-pigmentation in the fundus due to X-inactivation, and partial iris transillumination. They do not show any other symptoms exhibited by those affected by OA1.

Human Oa1 gene has been identified by positional cloning as a 40kb gene mapped to Xp22.3-Xp22.2. Later, a mouse homolog of the human Oa1 gene was also identified and cloned. It codes for a 404 amino acid long protein with up to three potential glycosylation sites. The transcript has been found to be expressing very well in retinal pigment epithelium and skin and to a much lesser extent in brain and adrenal glands.

Mutations in Oa1 have been well characterized and studied using various techniques like southern blot analyses, single-strand conformation polymorphism and sequence analysis. Most of these mutations have been reported to be occurring in the N-terminus and few in the trans-membrane regions but very rarely in the much conserved cytoplasmic C-terminus. Populations belonging to different ethnic groups have been extensively analyzed and a database has been created recording the details of mutations related to OA1. A total of 25 missense, 2 nonsense, 9 frameshift, and 5 splicing mutations have been reported till date. In addition to these mutations, there also occur several deletions in one or many of the exons of Oa1 gene, especially exon 2. These deletions are presumed to be because of unequal crossing-over due to the presence of flanking Alu regions. In some cases, the entire Oa1 gene is deleted along with other contiguous genes. Many different polymorphisms have also been detected, mainly in intron 1.

Tissue-specific control of Oa1 transcription is by a 617bp long E-box region bound by Mitf. Mitf has been shown to regulate expression of many melanosomal genes like TYR and TRP-1 through the E-box motif (CATGTG). Vetrini et al. have used adenoviral vectors to study tissue-specificity of Oa1 transcription through Mitf and observed that this regulation in conserved in human Oa1 gene.

The term albinism [L. albus means 'white'] refers to a heterogeneous group of congenital disorders in melanin pigment biogenesis. Pigmentation process maybe affected in one or many ways due to mutations. Abnormal pigmentation maybe at the level of embryogenesis in regions where melanocytes fail to populate. The melanin biosynthetic pathway may also be affected due to mutations. Sometimes one or many of the genes responsible for biogenesis of organelles may be mutated.

Albinism may manifest itself as oculocutaneous (OCA) or just ocular (OA). There occur at least ten different types of OCA and four types of OA. OCA refers to a group of autosomal recessive disorders in which melanin is reduced or even absent leading to pale skin with increased risk of skin cancer. OCA1 is caused due to mutations in tyrosinase gene affecting its catalytic or synthetic activity. OCA2 is a condition where TYR gene is not mutated but the P polypeptide is. Mutational defects in TRP-1 protein leads to OCA3.