Oculocutaneous Albinism

Oculocutaneous Albinism Overview

Unlike Ocular Albinism which typically only affects the eyes, Oculocutaneous Albinism affects the eyes, skin, and hair. There are several types of Oculocutaneous Albinism (OCA) with several subtypes but of them, the most commonly found are type 1 (OCA1) and type 2 (OCA2). Oculocutaneous Albinism type 1 has two parts, part “A” and part “B”—OCA1a & OCA1b.

OCA1a- A quick rundown:

White hair and skin at birth and throughout life
Does not tan
Irises are blue and fully translucent at birth and remain so throughout life
Retina does not develop melanin pigment
Visual acuity is usually between 20/100 and 20/400
Nystagmus and Strabismus is possible.
Involves tyrosinase enzyme--which converts tyrosine (an amino acid) into melanin

OCA1b- A quick rundown:

White or light yellow hair at birth but darkens with age, can change to a golden or light brown
Skin remains white but often has some generalized pigmentation
Tans with sun exposure
Iris color remains blue or change to a hazel/green or brown/tan
Transillumination shows in streaks or clumps of pigment in the iris
Fine granular pigment may develop over time in the retina
Visual acuity is usually between 20/100 and 20/200 but can be as good as 20/60
Nystagmus and Strabismus is possible.
Involves tyrosinase enzyme--which converts tyrosine (an amino acid) into melanin

OCA2- A quick overview:

Pigment in hair and skin ranges from minimal to near-normal.
Almost always have some pigment in skin and hair (yellow to blonde)
Iris color from blue to brown, usually without transillumination marks as seen in OCA1
Visual acuity much better than OCA1 but ranges from 20/20 to mild 20/100.
Carrier rate is 1:100
Nystagmus and Strabismus is possible.
Affects the p-protein
More common in African American decent

OCA4- A quick overview:

Indistinguishable from OCA2

In total, it is estimated that 1 in 20,000 people worldwide are born with Oculocutaneous Albinism. Types 1 and 2 are the most common, types 3 and 4 are less—3 being mostly found in Southern Africa and 4 more frequently seen in Korean and Japanese populations.

A few other types I will mention briefly:

Hermansky-Pudlak Syndrome (HPS)-a rare type of albinism which may involve bleeding disorders, bruising, lung problems and intestinal disorders. You can visit hpsnetwork.org for more info.

Chediak-Higashi Syndrome- another rare form of albinism characterized by an abnormality in certain types of white blood cells, which lower resistance to infection.

Griscelli Syndrome -an extremely rare type of albinism (60 known cases worldwide). It involves immunodeficiency and may also have associated neurological problems.

No comments:

Post a Comment