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HPS1 gene

Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

HPS1 gene

The HPS1 gene provides instructions for creating a protein essential to the formation of specialized cellular structures, and mutations in this gene are a primary cause of Hermansky-Pudlak syndrome type 1.

Normal Function

The HPS1 gene provides instructions for making a protein that forms part of a complex called biogenesis of lysosome-related organelles complex-3 (BLOC-3). This complex plays a role in the formation of a group of cellular structures called lysosome-related organelles (LROs). In particular, BLOC-3 helps turn on the process by which necessary proteins are transported to LROs during their formation. LROs are very similar to compartments within the cell called lysosomes, which digest and recycle materials. However, LROs perform specialized functions and are found only in certain cell types.

Within pigment-producing cells (melanocytes), LROs called melanosomes produce and distribute melanin, which is the substance that gives skin, hair, and eyes their color. A different type of LRO is found in platelets, the blood cells involved in normal blood clotting. These LROs, called dense granules, release chemical signals that cause platelets to stick together and form a blood clot. LROs are also found in other specialized cells, including certain cells of the lungs.

Health Conditions Related to Genetic Changes

Hermansky-Pudlak syndrome

At least 31 mutations in the HPS1 gene have been found to cause Hermansky-Pudlak syndrome type 1. Individuals with this form of the condition typically have oculocutaneous albinism, a condition characterized by fair skin, light-colored hair and eyes, and poor vision. They may also have bleeding problems and a severe lung disease called pulmonary fibrosis.

  • Mechanism: The HPS1 gene mutations impair the normal function of BLOC-3, disrupting the size, structure, and function of LROs in cells throughout the body.
  • Common Mutation: The most common mutation causes a duplication of genetic material within the HPS1 gene and is found in people from northwest Puerto Rico. Specifically, this mutation results in an extra 16 DNA building blocks (nucleotides) within the gene (written as 1470_1486dup16).
  • Clinical Impact: Because abnormal melanosomes do not distribute melanin properly, people with this syndrome have unusually light coloring. The absence of dense granules within platelets leads to bleeding problems, and pulmonary fibrosis may develop due to abnormal LROs in certain lung cells.

Other Names for This Gene

  • BLOC3S1
  • Hermansky-Pudlak syndrome 1
  • Hermansky-Pudlak syndrome 1 protein
  • Hermansky-Pudlak syndrome 1 protein isoform a
  • Hermansky-Pudlak syndrome 1 protein isoform c
  • Hermansky-Pudlak syndrome type 1
  • HPS
  • HPS1_HUMAN
  • MGC5277

Frequently Asked Questions

HPS1 typically presents with oculocutaneous albinism (fair skin, light hair, blue or gray eyes), severe visual impairment due to foveal hypoplasia, and a bleeding tendency from platelet dense granule deficiency. Unlike other albinism types, HPS1 patients often develop progressive pulmonary fibrosis and may have granulomatous colitis. The combination of these features points toward HPS1.
Pulmonary fibrosis is progressive and currently has limited treatment options. Antifibrotic medications such as pirfenidone or nintedanib can slow disease progression in some patients. Regular pulmonary function tests, high-resolution CT scans, and early referral to a pulmonologist are essential. In advanced cases, lung transplantation may be considered, though outcomes vary.
Diagnosis starts with a clinical assessment of pigmentation, bleeding history, and lung function. A skin biopsy can reveal absent or reduced melanosomes. Definitive confirmation requires genetic testing—usually a targeted HPS1 gene panel or whole-exome sequencing—to identify pathogenic mutations. A positive result is confirmed by Sanger sequencing of the variant.
Bleeding risk is managed by avoiding high-impact activities, using protective gear, and treating minor cuts promptly. For more significant bleeding, platelet transfusions or antifibrinolytic agents (e.g., tranexamic acid) may be necessary. Patients should carry a medical alert card and inform healthcare providers of their condition before any invasive procedures.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.