Hermansky-Pudlak Syndrome Without Pulmonary Fibrosis

Hermansky-Pudlak syndrome without pulmonary fibrosis as a complication includes three relatively mild types (HPS-3, HPS-5 and HPS-6) of Hermansky-Pudlak syndrome (HPS; see this term), a multi-system disorder characterized by ocular or oculocutaneous albinism, bleeding diathesis and, in some cases, granulomatous colitis.

Epidemiology

HPS-3 occurs as a genetic isolate in central Puerto Rico with a prevalence of 1/4000; additionally, around 15 non-Puerto-Rican cases of HPS-3 have been reported. Ten cases of HPS-5 have been reported and 25 cases of HPS-6, from which 20 come from an Israeli-Bedouin tribe.

Clinical description

These three types present with features of HPS including ocular or oculocutaneous albinisim, reduced visual acuity, horizontal nystagmus, easy bruising of soft tissues, epistaxis, and prolonged bleeding after dental extraction, surgery or childbirth. Women may present with medically significant menstrual bleeding. Complications of HPS may include reduced renal function and granulomatous colitis. Pulmonary fibrosis has not been found to develop in HPS-3, HPS-5 or HPS-6. The course of HPS with no pulmonary involvement is mild.

Etiology

HPS-3 is caused by mutations in the HPS3 gene (3q24), HPS-5 is caused by mutations in the HPS5 gene (11p15-p13) and HPS-6 is caused by mutations in the HPS6 gene (10q24.32). The gene products, HPS3, HPS5 and HPS6, are part of the multi-subunit complex BLOC-2 (biogenesis of lysosome-related organelles complex 2).

Genetic counseling

Transmission is autosomal recessive.