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. 2008 Jul 10:14:1293-7.

CNGA3 mutations in two United Arab Emirates families with achromatopsia

Yachna Ahuja  1 , Susanne Kohl, Elias I Traboulsi
Affiliations

CNGA3 mutations in two United Arab Emirates families with achromatopsia

Yachna Ahuja et al. Mol Vis. .

Abstract

Purpose: ACHROMATOPSIA RESULTS FROM MUTATIONS IN ONE OF THREE GENES: cyclic nucleotide-gated channel, alpha-3 (CNGA3); cyclic nucleotide-gated channel, beta-3 (CNGB3); and guanine nucleotide-binding protein, alpha-transducing activity polypeptide 2 (GNAT2). We report the responsible mutations in two United Arab Emirates families who have this autosomal recessive disease.

Methods: Clinical examinations were performed in seven patients from three nuclear families. Molecular genetic testing for common CNGA3 and CNGB3 mutations was undertaken using standard protocols.

Results: All patients were extremely light sensitive and had reduced visual acuity and no color perception. Fundus examinations did not show any visible abnormalities. After further pedigree analysis, two of the families were found to be linked through the paternal line. Two mutations in CNGA3 were identified: Arg283Trp and Gly397Val. Family A, the larger pedigree, had one branch in which two sisters and one brother were homozygous for the Gly397Val mutation and another branch in which a brother and sister were compound heterozygous for both aforenamed mutations. Family B, however, only had two brothers who were homozygous for the Arg283Trp mutation.

Conclusions: Achromatopsia in these two United Arab Emirates families results from two different mutations in CNGA3. Two branches of the same pedigree had individuals with both homozygous and compound heterozygous disease, demonstrating a complex molecular pathology in this large family.

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Figures

Figure 1
Figure 1
Pedigrees of family A and family B with autosomal recessive achromatopsia originating from the United Arab Emirates and carrying mutations in the CNGA3 gene. Family A has two branches carrying either the two heterozygous mutations R283W and G397V or being homozygous for the mutation G397V due to consanguinity of the parents. Patients of family B are both homozygous for the mutation R283W in the CNGA3 gene. Squares indicate males and circles females. Open symbols indicate healthy individuals, while shadings designate the affected patients. Arrows point to family members for whom DNA samples were available for genetic analysis. CNGA3 genotypes are given below each analyzed individual.
Figure 2
Figure 2
Identification of the novel CNGA3 mutation c.1190G>T Gly397Val in Family A. Electropherogram sections of exon 7 of CNGA3. Selected heterozygous or homozygous mutant sequences (middle and bottom rows) compared with the respective wild-type sequence (top row). Dotted framed encloses the nucleotide altered by the mutation.
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