BLOC1S3 gene


Gene (OMIM No.)
Function of gene/protein
  • Protein: Subunit 3 of Biogenesis of lysosomal organelles complex 1 (BLOC-1)
  • Involved in the normal biogenesis of lysosome-related organelles such as melanosomes and platelet dense granules
  • Also proposed to play a role in neurite extension (from UniProt)
Clinical phenotype
(OMIM phenotype no.)
  • Hermansky-Pudlak syndrome 8 (#614077)
  • Autosomal recessive
Ocular features
Systemic features
  • Skin and hair depigmentation
  • Bleeding diathesis (easy/prolonged bleeding, easy bruising, prolonged/heavy menorrhagia, epistaxis)
Key investigations
  • Orthoptic assessment and refraction
  • OCT to detect foveal hypoplasia
  • Visual evoked potentials to detect evidence of chiasmal misrouting
  • Eye movement recordings
  • Systemic assessment with a pediatrician, haematologists and other relevant specialists
Molecular diagnosisNext generation sequencing
  • Targeted gene panels (albinism)
  • Whole exome sequencing
  • Whole genome sequencing
  • Multidisciplinary approach
Therapies under research
  • None in clinical trials at present
Further information

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  1.  Starcevic M, Dell’Angelica EC. Identification of snapin and three novel proteins (BLOS1, BLOS2, and BLOS3/reduced pigmentation) as subunits of biogenesis of lysosome-related organelles complex-1 (BLOC-1). J Biol Chem. 2004;279(27):28393-28401
  2.  Morgan NV, Pasha S, Johnson CA, et al. A germline mutation in BLOC1S3/reduced pigmentation causes a novel variant of Hermansky-Pudlak syndrome (HPS8). Am J Hum Genet. 2006;78(1):160-166
  3.  Cullinane AR, Curry JA, Golas G, et al. A BLOC-1 mutation screen reveals a novel BLOC1S3 mutation in Hermansky-Pudlak Syndrome type 8. Pigment Cell Melanoma Res. 2012;25(5):584-591

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Updated on November 30, 2020
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