Finding genes involved in corneal endothelial dystrophies linked to human chromosome 20

The cornea of the eye is a highly specialised tissue, which forms a mechanical barrier to foreign material and refracts light. The transparency of the cornea is maintained as a result of a balance between its anatomy, physiology and metabolism. Corneal endothelial dystrophies affect the innermost layer of the cornea and can markedly reduce vision as a result of corneal endothelial cell dysfunction and the subsequent loss of corneal clarity. The work in this thesis focuses on the corneal endothelial dystrophies mapping to human chromosome 20: Posterior Polymorphous Dystrophy (PPD) and Congenital Hereditary Endothelial Dystrophy (CHED). The dominant form of CHED, CHED1, was mapped to a 2.7cM region between markers D20S48 and D20S471. New polymorphic markers were developed and used to refine the critical interval to 1.6 Mb by linkage analysis. Gene structures from the annotation of human chromosome 20 were confirmed experimentally prior to a systematic mutation screen of genes within the CHED1 region. Two families from the Czech Republic with the PPD phenotype were linked chromosome 20. The 30cM PPD region was refined to the 2.7cM CHED1 interval. This resulted in the exclusion of the VSX1 gene (Heon et al., 2002), previously identified as containing mutations responsible for the pathogenesis of PPD in a Canadian family. A founder effect was discovered for PPD between the two large families used for the analyses. Since no sequence changes were found to segregate with the CHED1 phenotype, an assessment of annotation completeness was accomplished using comparative genomic analysis. The sequence of the human chromosome 20 CHED1 interval and the syntenic mouse genome sequence were analysed. The emerging sequence from the syntenic region in rat and chimpanzee was also examined.EThOS - Electronic Theses Online ServiceGBUnited Kingdo