The Authors have studied a pair of MZ twins, both affected with ocular albinism, two boys—probably consanguineous—also affected with ocular albinism, a DZ opposite—sexed twin—pair with the male twin affected with ocular albinism and many relatives affected with localized or generalized pigment anomalies, and the female MZ twin-pair concordant as to total albinism, already described by Hanhart.
The Autors criticise current classifications of hereditary albinism which do not accord themselves with the samples and which do not explain the phenogenesis of the disease. They suggest to classify the hereditary forms of albinism in two fundamental classes. In the first one would be included the cases of total and non-total albinism depending on an enzymopathy which alters the normal melanogenesis. In the second one would be included the cases in which the specific enzymes, tough normally present, encounter some local causes enhibiting their action. Cases nos. I and II of the present work would belong to the first class, while cases nos. III and IV would belong to the second one.