Abstract
Abstract: :
Purpose: Congenital hereditary endothelial dystrophy (CHED) is a rare disorder of the cornea that affects the endothelium and is characterised by diffuse, bilateral corneal opacities during the first few years of life. The autosomal dominant form of the disease, CHED1, has previously been linked to a 3cM region of chromosome 20p11.2, flanked by markers D20S112 and D20S471. Our aim is to complete the transcript map in this region and identify the molecular basis of the disease through systematic mutation screening of candidate genes. Methods: As part of the human genome project, a reference sequence of chromosome 20 has been completed at the Wellcome Trust Sanger Institute. Computer assisted annotation of the CHED1 region has identified 17 known genes, 5 novel genes, 2 putative genes and 12 pseudogenes in the 2,737,013 base pairs of finished sequence. Experimental verification of gene structures and expression is being carried out for each of the genes by sequencing cDNA fragments obtained from PCR screening of cDNA libraries. Results: The expanding pool of genes with confirmed structures and of known or inferred function (based on protein similarity searches), has permitted the selection of candidates for further experimental analysis. Mutation screening is in progress across exons of genes such as structural genes that may maintain the architecture of the cell and genes that may be involved in cellular transport and homeostasis. Conclusion: In conclusion, the transcript map in the region between D20S112 and D20S471 on 20p11.2 is approaching saturation. Mutation screening of candidate genes is in progress, which may result in the identification of the gene implicated in the pathogenesis of CHED1.
Keywords: 371 cornea: endothelium • 418 gene mapping • 335 candidate gene analysis