CRYBB1 gene

Overview

Gene (OMIM No.)
Function of gene/protein
  • Protein: crystallin beta B1 (CRYBB1)
  • CRYBB1 proteins are highly soluble, lens-specific components
  • Interact with other crystallins to help maintain lens transparency
  • Also involved in lens development
Clinical phenotype
(OMIM phenotype no.)
  • Cataract 17, multiple types (#611544)
Inheritance
  • Autosomal recessive
  • Autosomal dominant (more common)
Ocular features
Systemic features
  • No extraocular features have been reported
Key investigations
  • Measurement of corneal diameter
  • 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
ManagementOcular
Therapies under research
  • None at present
Further information

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Additional information

Most congenital cataract cases due to pathogenic mutations in CRYBB1 gene are autosomal dominant in nature. The only autosomal recessive cases were reported by Cohen et al in affected family members of two unrelated consanguineous Bedouin families homozygous for a 1-base pair deletion in exon 2 of CRYBB1 (168delG).[1]

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References

  1.  Cohen D, Bar-Yosef U, Levy J, et al. Homozygous CRYBB1 deletion mutation underlies autosomal recessive congenital cataract. Invest Ophthalmol Vis Sci. 2007;48(5):2208‐2213
  2.  Mackay DS, Boskovska OB, Knopf HL, Lampi KJ, Shiels A. A nonsense mutation in CRYBB1 associated with autosomal dominant cataract linked to human chromosome 22q. Am J Hum Genet. 2002;71(5):1216‐1221
  3.  Wang KJ, Wang S, Cao NQ, Yan YB, Zhu SQ. A novel mutation in CRYBB1 associated with congenital cataract-microcornea syndrome: the p.Ser129Arg mutation destabilizes the βB1/βA3-crystallin heteromer but not the βB1-crystallin homomer. Hum Mutat. 2011;32(3):E2050‐E2060
  4.  Willoughby CE, Shafiq A, Ferrini W, et al. CRYBB1 mutation associated with congenital cataract and microcornea. Mol Vis. 2005;11:587‐593

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Updated on November 30, 2020
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