Hermansky-Pudlak syndrome type 2 (HPS-2) is a type of Hermansky-Pudlak syndrome (HPS; see this term), a multi-system disorder characterized by oculocutaneous albinism, bleeding diathesis and neutropenia.
To date HPS-2 has been described in eight patients.
HPS-2 presents with features of HPS including 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. In addition, HPS-2 patients present with recurrent infections due to neutropenia and impaired cytotoxic activity. Recently, pulmonary fibrosis has been described in some HPS-2 cases.
HPS-2 is caused by mutations in the AP3B1 gene (5q14.1) and is transmitted in an autosomal recessive manner. The gene product is the Beta 3A subunit of adaptor protein 3 (AP3), involved in vesicle formation and protein sorting.
The neutropenia is responsive to granulocyte-cell stimulating factor (G-CSF).
Last update: March 2010
- Dr William GAHL
- Dr Marjan HUIZING