Hermansky-Pudlak syndrome: A group of genetic diseases characterized by a deficiency of pigment in the skin and eye, a bleeding tendency resulting from a platelet storage pool deficiency, and systemic disorders related to deficient function of lysosomes. Abbreviated HPS. Albinism that occurs in the eyes results in significant reduction in visual acuity. Pulmonary fibrosis and granulomatous colitis are known complications. The diseases are inherited as an autosomal recessive trait and are due to multiple different gene mutations. Diagnosis is made by examining blood platelets under an electron microscope or by genetic testing. There is currently no treatment for HPS. Also known as albinism with hemorrhagic diathesis, pigmented reticuloendithelial cells, and delta-storage pool disease.