[Porokeratosis of Mibelli in two monozygotic twins (author's transl)].

Two monozygots twins had porokeratosis Mibelli and a deep mental retardation. The exploration of this nervous components is negative. The porokeratosis in one twin had in several sites the aspect of a skin's horn. The demonstration of the monozygotis was made by the same repartition of 16 characters (HLA, blood groups). The boys had the same aspect and the same skin disease. The twin method is discussed. The existence of the porokeratosis of Mibelli in two monozygotic twins is an argument for the genetic mechanism of the disease. The familial cases of porokeratose Mibelli reported by Bataillard, Civatte, Vigne, Bloom, have consistent features for an dominant autosomic transmission with variations in the penetrance and the expressivity of the skin disease.