Reduction in melanin production specifically in the peripheral retina during embryonic development can trigger other symptoms such as abnormal nerve fiber projection that causes defects in neuronal migration that interrupts visual pathways and creates reduced visual acuity in the range of 20/60 to 20/400. This vision acuity is dependent upon the amount of pigmentation in the eye. Acuity is usually better in individuals with greater amounts of pigment. Aside from decreased pigment in the iris and retina, optic changes include decreased visual acuity, misrouting of the optic nerves at the chiasm, and nystagmus.OCA1 is one of the more extreme types of albinism where the iris is translucent and the eye appears pink or red in ambient light and have white skin with slight to no pigmentation when other types may have residual pigmentation. OCA1 is caused by mutations in the TYR gene, where there is a complete lack of tyrosinase activity. Genetics
The tyrosinase (TYR) gene is located on chromosome 11q14. This protein coding gene produces tyrosinase, an enzyme which catalyzes a total of three steps in the conversion of tyrosine to the end product, melanin. This enzyme and conversion process takes place within melanocytes, which are specialized cells for melanin production. Melanin is a large group of molecules that give skin, eyes, and hair their respective colors. It is also partially responsible for vision, as it protects the light sensitive portion of the eye, the retina, through absorbing light.
Individuals affected by OCA1A should be attentive to the amount of sun exposure they experience and wear proper protection such as clothing that covers the skin. Additionally, individuals may need corrective visual aids for their visual acuity of 1/10 or less with intense photophobia. Visual aids can both improve vision or protect eyes from bright lights. These visual aids can be adjusted for based on individual needs. Individuals should receive annual skin evaluation to access for damage or skin cancers that can be induced from sun exposure. In some situations, therapy or surgery can correct crossed eyes (strabismus) or rapid eye movements (nystagmus). Epidemiology
The highest frequency of Albinism type IA is in Northern Ireland, with a phenotype frequency of around 1: 10,000. First cousin - marriages accounted for 4.5% of the parents of patients. Additionally, symptoms that could be heterozygous mutations, such as abnormal iris translucency occurred in 70% of the parents and children of individuals affected with this condition. In general, the phenotypical appearance of OCA1A is associated with northern and western Europe. This is because over 50% of OCA1 subjects are Caucasians. OCA1 is also the most common form of Albinism in China and Japan. The overall frequency is 1: 20,000 people in the world. References


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