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Oculocutaneous Albinism
Oculocutaneous
albinism (OCA) is a heterogeneous group of congenital disorders characterized
by hypopigmentation of skin, hair, and eyes associated with other developmental
ocular defects. OCA patients are often considered as legally blind and in
India, it is one of the 4 major causes of childhood blindness. Long-term sun
exposure greatly increases the risk of skin damage and an aggressive form of
skin cancer called melanoma, in people with this condition. Mutations in genes
regulating the multistep process of melanin biosynthesis cause this spectrum of
disorders. The four classical types of oculocutaneous albinism are designated
as OCA1 (OCA1A:
MIM: 203100 and
OCA1B:
MIM: 606952),
OCA2 (
MIM: 203200),
OCA3 (
MIM: 203290)
and OCA4 (
MIM: 606574)
caused by TYR,
OCA2, TYRP1 and
SLC45A2 genes, respectively. OCA1 is characterized by white hair, very
pale skin, and light-colored irises. OCA2 and OCA4 have overlapping clinical
features (a creamy white color and hair may be light yellow, blond, or light
brown) that are generally less severe than OCA1. OCA3 affected individuals have
reddish-brown skin, ginger or red hair and hazel or brown irises with milder
vision abnormalities than the other forms of OCA. Overall, an estimated 1 in
20,000-30,000 people worldwide are born with oculocutaneous albinism however,
the frequency differs from country to country. In India, OCA1 is the most
prevalent type of OCA followed by OCA2.
This database presently holds the relevant data for OCA1, OCA2, OCA3 and OCA4.
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