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HPS3 gene

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

HPS3 gene

The HPS3 gene is essential for the formation of specialized cellular structures called lysosome-related organelles, and mutations in this gene lead to a form of Hermansky-Pudlak syndrome.

Normal Function

The HPS3 gene provides instructions for making a protein that forms part of a complex called biogenesis of lysosome-related organelles complex-2 (BLOC-2). This complex controls the sorting and transport of proteins into lysosome-related organelles (LROs) during their formation.

LROs are specialized compartments found in specific cell types:

  • Melanocytes: These cells contain LROs called melanosomes, which produce and distribute melanin, the substance that gives skin, hair, and eyes their color.
  • Platelets: These blood cells contain LROs called dense granules, which release chemical signals that cause platelets to stick together and form blood clots.

Health Conditions Related to Genetic Changes

Hermansky-Pudlak syndrome

At least 7 mutations in the HPS3 gene have been found to cause Hermansky-Pudlak syndrome type 3, a mild form of the condition. Affected individuals typically experience oculocutaneous albinism—characterized by fair skin, light-colored hair and eyes, and poor vision—as well as potential bleeding problems.

Mutations in the HPS3 gene impair the function of BLOC-2, which disrupts the size, structure, and function of LROs. Because abnormal melanosomes cannot distribute melanin properly, individuals develop albinism. Similarly, the absence of dense granules within platelets leads to bleeding issues.

Specific mutations include:

  • 3.9kb deletion: A common mutation found in individuals from the central region of Puerto Rico that prevents the production of any HPS3 protein.
  • Splice-site mutation (1163+1G>A): Found in individuals of Ashkenazi Jewish background, this mutation disrupts the gene's instructions, resulting in an abnormally short protein.

Frequently Asked Questions

Individuals with HPS3-related Hermansky-Pudlak syndrome type 3 typically experience oculocutaneous albinism, characterized by fair skin, light-colored hair, light-colored eyes (often blue or hazel), and significant vision problems such as reduced visual acuity, nystagmus (involuntary eye movements), and photophobia (light sensitivity). They may also have a tendency for easy bruising or prolonged bleeding due to platelet dysfunction, which can impact activities requiring clotting, like surgery or injury.
Bleeding problems are managed by avoiding medications that impair platelet function (like aspirin or NSAIDs) and taking precautions during procedures that carry a risk of bleeding. In cases of significant bleeding, treatments may include desmopressin, platelet transfusions, or other blood products. Patients should always inform their healthcare providers about their bleeding disorder before any surgery or dental work.
Diagnosis often begins with a clinical evaluation of albinism and bleeding tendencies. Genetic testing, typically using a blood sample, is then performed to identify specific mutations in the HPS3 gene. For individuals of Puerto Rican or Ashkenazi Jewish descent, specific tests for the common 3.9kb deletion or the 1163+1G>A splice-site mutation may be prioritized.
Long-term considerations primarily revolve around managing vision impairment and preventing complications from bleeding. Regular ophthalmological care is essential. While HPS3-related HPS is considered a milder form, individuals should be monitored for any signs of increased bleeding tendency. Unlike some other HPS types, lung fibrosis and inflammatory bowel disease are generally not associated with HPS3.
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.