CRYBA2 gene


Gene (OMIM No.)
Function of gene/protein
  • Protein: crystallin beta A2
  • Lens-specific protein with both structural and functional components
  • Involved in lens development
  • Highly soluble and transparent structure helps to maintain lens transparency
  • Functions as a molecular chaperone in its oxidised form
  • Binds to misfolded proteins to prevent aggregation
Clinical phenotype
(OMIM phenotype no.)
  • Autosomal dominant
Ocular features
  • Incomplete penetrance
  • Congenital cataracts most common but 2 patients were diagnosed later (aged 9 and 38 years)
  • Variable morphology: multifocal congenital cataract, juvenile or posterior polar cataract
  • Eccentric pupil
  • Myopia
  • Glaucoma
Systemic features
  • No extraocular features have been reported
Key investigations
  • B-scan USS to measure axial length to document microphthalmia and detect any posterior segment abnormalities
  • Electrophysiology
  • TORCH screen
  • MRI brain and orbit
  • Assessment with a paediatrician if suspicious of systemic involvement
Molecular diagnosisNext generation sequencing
  • Targeted gene panels (cataract)
  • Whole exome sequencing
  • Whole genome sequencing
Therapies under research
  • None at present
Further information

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  1.  Hulsebos TJ, Cerosaletti KM, Fournier RE, et al. Identification of the human beta A2 crystallin gene (CRYBA2): localization of the gene on human chromosome 2 and of the homologous gene on mouse chromosome 1. Genomics. 1995;28(3):543‐548
  2.  Lapko VN, Smith DL, Smith JB. Expression of betaA2-crystallin in human lenses. Exp Eye Res. 2003;77(3):383‐385
  3.  Puk O, Ahmad N, Wagner S, Hrabé de Angelis M, Graw J. First mutation in the βA2-crystallin encoding gene is associated with small lenses and age-related cataracts. Invest Ophthalmol Vis Sci. 2011;52(5):2571‐2576. Published 2011 Apr 20
  4.  Reis LM, Tyler RC, Muheisen S, et al. Whole exome sequencing in dominant cataract identifies a new causative factor, CRYBA2, and a variety of novel alleles in known genes. Hum Genet. 2013;132(7):761‐770

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Updated on November 30, 2020

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