Hermansky-Pudlak syndrome in two African-American brothers
Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder characterized by oculocutaneous albinism, a bleeding disorder, and, in some patients, granulomatous colitis and/or a fatal pulmonary fibrosis. There are eight different subtypes of HPS, each due to mutations in one of eight different genes, whose functions are thought to involve intracellular vesicle formation and trafficking. HPS has been identified in patients of nearly all ethnic groups, though it has primarily been associated with patients of Puerto Rican, Northern European, Japanese and Israeli descent. We report on the diagnosis of HPS type 1 in two African-American patients. Both brothers carried compound heterozygous mutations in HPS1: previously reported p.M325WfsX6 (c.972delC) and a novel silent mutation p.E169E (c.507G > A), which resulted in a splice defect. HPS may be under-diagnosed in African-American patients and other ethnic groups. A history of easy bruising or evidence of a bleeding disorder, combined with some degree of hypopigmentation, should prompt investigation into the diagnosis of HPS.