Objective: To investigate the genetic association between ankylosing spondylitis (AS) and single nucleotide polymorphisms (SNP) of collagen 6A1 gene (COL6A1), the candidate gene for ossification of the posterior longitudinal ligament.
Methods: One-hundred thirty Korean patients with AS (M: 116, F: 14, age: 29.0 +/- 4.6) and 130 age- and sex-matched healthy subjects were recruited. The SNP of G365G, IVS15+39 C/T, IVS21+18 A/C by Snap shot assay and the SNP of IVS32-29T/C, IVS33+15G/A, IVS33+20A/G, and IVS33+55A/G by direct sequencing were genotyped and analyzed. Bonferroni correction was applied to multiple comparisons.
Results: The observed allelic frequencies for these SNP met Hardy-Weinberg equilibrium in all AS and controls. We also found an additional 2 SNP (R783Q and IVS33+88C/T) during direct sequencing. Therefore, a total of 9 SNP were analyzed in this study. There were no significant associations of allelic and genotype variations between AS and controls. The presence of uveitis was marginally associated with a haplotype (CC in G365G + IVS15+39 C/T). The variation of allele or haplotype of COL6A1 is not significantly associated with "more ossified disease."
Conclusion: Because the genetic variations of COL6A1 could not be correlated with the occurrence of AS in Koreans, we conclude that despite common clinical features, AS and ossification of posterior longitudinal ligament are not genetically related, and the hyperostotic condition seen in the 2 diseases might be regulated differently. Further SNP of COL6A1 were not related to radiographic progression of AS. However, we found that the occurrence of uveitis might be related to the genetic variations of COL6A1 in patients with AS.