Genetic analysis of two Indian families affected with congenital hereditary endothelial dystrophy: two novel mutations in SLC4A11.

PURPOSE

The autosomal recessive form of congenital hereditary endothelial dystrophy (CHED2) is a rare eye disorder caused by mutations in the SLC4A11 gene located at the CHED2 locus on chromosome 20p13-p12. The purpose of this study was to carry out genetic analysis of CHED2 in two Indian families.

METHODS

Blood samples were collected from individuals for genomic DNA isolation. In order to see if these families had mutations in the SLC4A11 gene, we selected 11 microsatellite markers from the CHED2 candidate region and used them to genotype the families. DNA sequence analysis was used for mutation detection. Allele-specific PCR was used to determine the segregation of mutations in families and also to determine if the mutations were present in 100 ethnically matched normal control chromosomes.

RESULTS

Haplotype analysis suggested linkage of the disorder to the CHED2 locus in both families. DNA sequence analysis showed a novel indel mutation, c.859_862delGAGAinsCCT (E287fsX21) in exon 8 of the SLC4A11 gene in one family. This mutation is predicted to truncate the protein with a lack of all 14 transmembrane domains. DNA sequence analysis of the second family showed a novel in-frame deletion mutation c.2014_2016delTTC or 2017_2019delTTC which will lead to the loss of a phenylalanine residue at position 672 or 673 (F672del or F673del). The mutant protein is expected to lack a conserved phenylalanine residue in transmembrane domain number 8.

CONCLUSIONS

This study reports two novel mutations in two CHED2 families and increases the spectrum of mutations in SLC4A11 to a total of 16. PCR-based screening methods were developed for both mutations for rapid screening of individuals.