Albinism

Synonyms

Ocular hypopigmentation; Nystagmus

Definition

Albinism is a genetic impairment of melanin production (melanogenesis) characterized by congenital hypopigmentation of the eyes, skin, and hair (oculocutaneous albinism, OCA) or of the eyes alone (ocular albinism, OA). The inheritance pattern of these conditions is different. OCA has an autosomal recessive transmission, whereas OA is X-linked recessive.

Etiology

In albinism there is complete or partial deficiency of melanin, which is responsible for the natural pigmentation of the skin, hair, and eyes. Melanin is normally produced in the melanosome, an intracellular organelle of melanocytes, which are derived from two embryonic tissues: the neural crest and optic cup. Melanocytes originating from the neural crest are present in the skin (epidermal-dermal junction), hair follicles, and eyes (choroid and iris stroma), whereas melanocytes of the retinal pigment epithelium are derived from the neuroectoderm of the optic cup. Melanin is...