HPS1 gene

HPS1, biogenesis of lysosomal organelles complex 3 subunit 1

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.

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. The HPS1 gene mutations that cause Hermansky-Pudlak syndrome type 1 impair the normal function of BLOC-3, disrupting the size, structure, and function of LROs in cells throughout the body. 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).

Because the abnormal melanosomes do not distribute melanin properly, people with Hermansky-Pudlak syndrome have unusually light coloring of the skin, hair, and eyes. The absence of dense granules within platelets leads to bleeding problems in affected individuals. Pulmonary fibrosis may also develop due to abnormal LROs in certain lung cells.

Cytogenetic Location: 10q24.2, which is the long (q) arm of chromosome 10 at position 24.2

Molecular Location: base pairs 98,415,068 to 98,446,963 on chromosome 10 (Homo sapiens Annotation Release 108, GRCh38.p7) (NCBI)

Cytogenetic Location: 10q24.2, which is the long (q) arm of chromosome 10 at position 24.2
  • 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
  • MGC5277