Ocular albinism type 1: More than meets the eye

Ocular albinism type 1 (OA1) is an X-linked recessive disorder characterize d by a severe reduction of visual acuity, and hypopigmentation of the retin a that leads to nystagmus, strabismus, and photophobia/photodysphoria. Micr oscopic examination of both retinal pigment epithelium and skin melanocytes in OA1 reveals the presence of macromelanosomes, suggesting that the OA1 g ene product plays a role in melanosome biogenesis. Studies of mutations ide ntified from OA1 patients and an Oa1 knock-out mouse model further implicat e OA1 protein function in the late stage of melanosome development. Because its effects are primarily limited to the eye, OA1 represents an ideal mode l system to study the relationship between pigmentation and visual developm ent. Based upon sequence homology and biochemical studies, OA1 may represen t a novel intracellular G-protein coupled receptor. Understanding the funct ion of OA1 will contribute greatly to our understanding of melanosome bioge nesis and the role of pigmentation in visual development.