Abstract
Abstract: :
Purpose: Anterior segment diseases including aniridia occur in the dog. The purpose of this study is to evaluate the canine PAX6 gene for the presence of causal mutations and to determine both its map position and transcriptional complexity in the canine genome. Methods: A canine pedigree was identified in which aniridia segregates as an autosomal recessive trait. Whole blood was used to make genomic DNA for analysis. PAX6 cDNA was cloned by RT-PCR from a canine retinal cDNA library. To test for the presence of multiple transcripts, primers were designed from human isoform b and used opposite canine primers. A canine radiation-hybrid (RH3000) panel was used to map PAX6 in relation to 3 genes on CFA18 (WT1, CD44, COLF1). To facilitate exon scanning in normal, affected, and carrier animals, primers were designed to span both introns and exons. Results: The entire 1289 bp coding sequence of canine PAX6 was cloned and shows 97% homology with the human sequence and 99.8% homology with the human protein. Unlike the mouse, gene organization is conserved between canine and human. Both isoforms of the PAX6 gene (one with and one without exon 5a) have been detected in a cDNA library. This indicates that both PAX6 gene isoforms are transcribed in the dog as in the human. Canine PAX6 was mapped to CFA18 which has synteny to a region of HSA11p13 where PAX6 is located in man. Conclusion: Preliminary evidence suggests that both canine and human PAX6 orthologs are similar at different levels: sequence, gene structure, map location, and transcriptional complexity. Exons from aniridia affected and carrier dogs are being scanned for mutations in PAX6.
Keywords: 316 animal model • 318 anterior segment • 335 candidate gene analysis