COL9A2 allelotypes in intervertebral disc disease

An allelic variation of the COL9A2 gene encoding the alpha (2)-chain of col lagen IX has recently been identified as a genetic risk factor for interver tebral disc prolapse, resulting in a tryptophane (Trp) substitution at posi tion 326 of the protein. To enable quick screening of a large population we established a single enzyme (BsmFI) restriction assay which was validated by screening disc tissue samples of 250 patients (age, 47.1 +/- 13.7 years) . Positive results were confirmed by nucleotide sequencing. The Trp allele was found in three patients (1.2%) who suffered from their first prolapse a nd mere significantly older (70.1 +/- 8.5 years) than the other 247 patient s. Since the substitution affects a domain covalently linked to collagen II fibrils, me conclude that this allelotype may contribute to reduced collag en crosslinking, disc instability and eventually prolapse in the elderly. ( C) 2000 Academic Press.