Albinism results from an inborn error of metabolism that involves the con-version of tyrosine to a brown or black insoluble polymer. Melanogenesis takes place in melanocytes, a group of spe-cialized cells. The first step, the hydroxy-lation of tyrosine to dihydroxyphenylalanine ((DOPA), is catalyzed by tyro-sinase. The second step, the oxidation of DOPA to the quinone, is also cata-lyzed by tyrosinase. The rest of the pathway leading to the production of the polymer (melanin) may be nonenzy-matic (1).

Although albinism in man is most often caused by a recessive autosomal gene, genetic heterogeneity may be present. The Trevor-Roperpedigree (2) of two albino parents producing normally pigmented offspring is suggestive evi-dence for at least two different types of recessive albinism in man. Supportive evidence comes from the experiments of Witkop, Van Scott, and Jacoby (3) who placed unfixed albino hair bulbs into a solution of L-tyrosine (50 milli-grams per 100 milliliters, pH 6.8). They observed that the hair from some al-binos formed pigment, but the hair from others did not. Genetic heterogeneity is not unexpected since a mutation in the structural gene, a controlling gene involved in the production of tyrosinase, or at some other locus resulting in the presence in themelanocyte of some en-zyme-binding substance, would all dis-rupt melanogenesis. Albinism occurs at different frequen-cies in various human populations. In Europe the overall frequency is about 1 in 20,000, with estimates ranging from 1 in 10,000 in Norway to about 1 in 30,000, or less, in southern Europe (4). In marked contrast are Indian popula-tions in Central and North America. The Cuna Indians of San Blas Province,