Hermansky-Pudlak syndrome.

A 55-year-old man had oculocutaneous albinism and a history of frequent bruising following minimal trauma. The simultaneous occurrence of these features was first described by Hermansky and Pudlak in 1959. The Hermansky-Pudlak syndrome follows an autosomal recessive trait and is most frequently found in Puerto Rico and in the Swiss alps. It consists of the triad phenotype of hypopigmentation, prolonged bleeding time due to platelet storage pool deficiency and accumulation of ceroid pigment in lysosomal organelles. Other serious features are pulmonary fibrosis and granulomatous colitis. The disorder is caused by mutations in the HPS1 gene on chromosome 10q23. The HPS1 gene product is involved in the trafficking of melanosomes, platelet dense bodies, and lysosomes.