An 8 bp deletion in exon 51 of the COL4A5 gene of an Alport syndrome patient

Alport syndrome (AS) is an X-linked progressive glomerulonephritis associated with high tone sensorineural deafness, characteristic eye lesions and glomerular basement membrane defects that can be detected by electron microscopy. Several cases of AS have been shown to be associated with mutations in the COL4A5 gene, the precise defect being unique to each pedigree described. Major structural rearrangement are expected to represent only 10% of all AS defects. To identify the remaining 90% of mutations, we have applied chemical mismatch analysis and direct sequencing to the products of amplification of individual exons from COL4A5 genomic DNA. We have identified an 8 bp deletion in exon 51 (previously referred to as exon 1) in one out of 30 patients screened by this method.