May 2008
Volume 49, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2008
Two Gja8 Mutations: An Insertion Causing a Recessive Triangular Cataract, and a Rare Polymorphism
Author Affiliations & Notes
  • J. Graw
    Helmholtz Center Munich, Neuherberg, Germany
    Inst of Developmental Genetics,
  • N. Klopp
    Helmholtz Center Munich, Neuherberg, Germany
    Inst of Epidemiology,
  • T. Illig
    Helmholtz Center Munich, Neuherberg, Germany
    Inst of Epidemiology,
  • W. Schmidt
    Center of Ophthalmology, Universities Giessen and Marburg, Giessen, Germany
  • Footnotes
    Commercial Relationships  J. Graw, None; N. Klopp, None; T. Illig, None; W. Schmidt, None.
  • Footnotes
    Support  None.
Investigative Ophthalmology & Visual Science May 2008, Vol.49, 4072. doi:https://doi.org/
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      J. Graw, N. Klopp, T. Illig, W. Schmidt; Two Gja8 Mutations: An Insertion Causing a Recessive Triangular Cataract, and a Rare Polymorphism. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4072. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : Aim of the study was the characterization of underlying mutations in two cataract families.

Methods: : Families suffering from congenital cataracts have been collected in Gießen (Germany). Lens material from surgeries was collected, immediately frozen at -80oC and used for cDNA production. Blood was taken from the probands and available family members. PCR amplified DNA fragments were characterized by sequencing and restriction digest.

Results: : The proband LB suffers from a diffuse white lens opacity; the parents are healthy. In the cDNA coding for GJA8, a T741->G nucleotide substitution was observed (I247M amino-acid exchange); this mutation was reported previously to be causative for cataracts. Surprisingly, the same mutation was identified in the healthy mother suggesting that it has no full penetrance or is even a rather rare polymorphism than a cataract-causing mutation.The proband AD suffers from a dense, triangular nuclear cataract. The parents are consanguineous and the mother and grandmother suffer from a discrete, symmetric opacity of the fetal lens nucleus. In the proband’s lens cDNA of GJA8, a homozygous insertion of one G was observed after pos. 776 leading to a frame shift and 123 novel amino acids. The homozygous mutation was confirmed in the genomic DNA and also present in the cataract-operated brother of the proband; all other family members investigated were heterozygous. The mutation could not be detected in 96 healthy controls from Germany.

Conclusions: : While the I247M mutation is most likely a rare polymorphism or is not fully penetrant, the ins776G mutation causes a recessive triangular cataract with variable expressivity of a weak phenotype in heterozygotes.

Keywords: cataract • genetics • gap junctions/coupling 
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