[Hermansky-Pudlak syndrome in a Valais village].

Amongst 13 subjects with albinism observed in a village in the Valais, 7 present the clinical and laboratory findings of the Hermansky-Pudlak syndrome. Because of the close family links and the numerous consanguine marriages present in the pedigree, it is probable that the 5 subjects who could not be examined also suffer from the same syndrome. It has an autosomal recessive mode of inheritance. In this isolate the gene and heterozygote frequencies are, respectively, 1:12 and 1:6. Clinically the hemorrhagic diathesis is moderate, the visual and cutaneous symptoms predominate. The platelet dysfunction results from a lack of storage of components (Ca++, nucleotides, amines) normally present in the dense granules. The lack of dense granules is demonstrated by electron and fluorescence microscopy. This structural anomaly is present in the megacaryocyte before individualization of the platelets. Giant melanosomes were found in skin melanocytes.