Albinism

Abstract

Albinism includes a group of inherited, congenital, generalized, hypomelanotic conditions in which melanocytes are present in integument and the eyes and are accompanied by specific ocular signs. The ocular changes include congenital nystagmus, hypoplasia of the fovea, hypopigmentation of the fundus, abnormal decussation of the optic neurons at the chiasm, decreased pigment in the irides frequently with photophobia; and decreased visual acuity.1 Traditionally, two major forms of albinism have been recognized, oculocutaneous (OCA) and ocular (OA). OCA was believed to involve the melanogenic system of integument and eye, whereas OA was thought to involve only melanin production in the eye. Present evidence indicates that all forms of albinism are OCA defects with distinct but minor changes in integument in the ocular forms of the condition.2–4 Melanin macroglobules (formerly macromelanosomes) are present in the skin of both males affected with X-linked ocular albinism (Nettleship-Falls) (XOAN) and carrier females.2,3 5–7 Patients with autosomal recessive ocular albinism (AROA) have darkly pigmented hair, but their skin is more lightly pigmented than their unaffected siblings and does not tan or tans only slightly.4 Thus, strictly speaking, these are forms of OCA; however, as the major clinical features are limited to the eye, the distinction of OCA and OA types is retained in a clinical context.As recent publications have reviewed disorders of pigmentation,1,8,9 this presentation will focus upon procedures useful in providing a diagnosis of types of albinism, evidence from matings for allelism or nonallelism of albinotic phenotypes, and some recent advances in pigment research.