Abstract
Purpose: :
Mutations in COL8A2 gene which encodes the alpha 2 (VIII) collagen chain have been identified in both familial and sporadic cases of Fuchs endothelial corneal dystrophy (FECD). Heterozygous mutations in the SLC4A11 gene also cause late-onset FECD. Therefore we screened for COL8A2, SLC4A11 gene variants in Indian patients with FECD.
Methods: :
Eighty patients with clinically diagnosed Fuchs’ endothelial dystrophy and hundred age matched normal individuals were recruited. Genomic DNA was isolated from peripheral blood leukocytes. Mutations in COL8A2 coding regions were screened using PCR, SSCP, RFLP analysis and Bi-Directional Sequencing. SLC4A11 gene mutations were analyzed using Bi-Directional Sequencing. Fischer’s exact test or Pearson’s chi squared test were used to predict the statistical association of genotypes with the phenotype.
Results: :
Screening of COL8A2 gene revealed a known pathogenic mutation Arg155Gln (c.464G>A) along with two novel polymorphisms, Asn548Ser, Asp537Asn and two reported silent variations Gly495Gly, Ala35Alawere also identified. In SLC4A11 gene, novel Val658Val, Asn553Asn and reported Ala135Ala, Ser213Ser variants were identified . However all the variations identified in both the genes were also present in unaffected controls.
Conclusions: :
This is probably the first study analyzing COL8A2 gene in Indian patients with FECD. Ala35Ala and Gly495Gly, which are synonymous substitutions, showed statistically significant association with FECD. However the previously reported mutations (Leu450Trp, Arg304Gln, Arg434His, and Gln455Lys) presumed to play a pathogenic role in cases of FECD were not identified and no other pathogenic mutations were identified in COL8A2. Merely silent changes, which showed statistically insignificant association with FECD, were identified in the screening of SLC4A11 gene. These results suggest that COL8A2, SLC4A11 genes may not be responsible for FECD in patients examined in this study.
Keywords: gene screening • genetics • cornea: endothelium