GJA8 gene

Overview

Gene (OMIM No.)
Function of gene/protein
  • Protein: gap junction alpha 3 protein/ connexin 50
  • Structural component of lens fibre gap junctions
  • Formation of channels through which neighboring cells can communicate and allow small molecules and ions to diffuse between cells
  • Maintaining lens transparency and its optical properties by regulating ionic and water balance in lens cells
Clinical phenotype
(OMIM phenotype no.)
  • Cataract 1, multiple types (#116200)
Inheritance
  • Autosomal dominant
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
  • Assessment with a pediatrician 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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References

  1.  Arora A, Minogue PJ, Liu X, et al. A novel connexin50 mutation associated with congenital nuclear pulverulent cataracts. J Med Genet. 2008;45(3):155‐160
  2.  Berry V, Mackay D, Khaliq S, et al. Connexin 50 mutation in a family with congenital “zonular nuclear” pulverulent cataract of Pakistani origin. Hum Genet. 1999;105(1-2):168‐170
  3.  Gong X, Baldo GJ, Kumar NM, Gilula NB, Mathias RT. Gap junctional coupling in lenses lacking alpha3 connexin. Proc Natl Acad Sci U S A. 1998;95(26):15303‐15308
  4.  Gong X, Li E, Klier G, et al. Disruption of alpha3 connexin gene leads to proteolysis and cataractogenesis in mice. Cell. 1997;91(6):833‐843
  5.  Polyakov AV, Shagina IA, Khlebnikova OV, Evgrafov OV. Mutation in the connexin 50 gene (GJA8) in a Russian family with zonular pulverulent cataract. Clin Genet. 2001;60(6):476‐478
  6.  Shiels A, Mackay D, Ionides A, Berry V, Moore A, Bhattacharya S. A missense mutation in the human connexin50 gene (GJA8) underlies autosomal dominant “zonular pulverulent” cataract, on chromosome 1q. Am J Hum Genet. 1998;62(3):526‐532
  7.  White TW, Goodenough DA, Paul DL. Targeted ablation of connexin50 in mice results in microphthalmia and zonular pulverulent cataracts. J Cell Biol. 1998;143(3):815‐825
  8.  Willoughby CE, Arab S, Gandhi R, et al. A novel GJA8 mutation in an Iranian family with progressive autosomal dominant congenital nuclear cataract. J Med Genet. 2003;40(11):e124

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Updated on November 30, 2020
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