Support of positive association in family-based genetic analysis between COL27A1 and Tourette syndrome

Recently, a genome-wide association study has indicated associations between single nucleotide polymorphisms in the Collagen Type XXVII Alpha 1 gene (COL27A1) and Tourette syndrome in several ethnic populations. To clarify the global relevance of the previously identified SNPs in the development of Tourette syndrome, the associations between polymorphisms in COL27A1 and Tourette syndrome were assessed in Chinese trios. PCR-directed sequencing was used to evaluate the genetic contributions of three SNPs in COL27A1(rs4979356, rs4979357 and rs7868992) using haplotype relative risk (HRR) and transmission disequilibrium tests (TDT) with a total of 260 Tourette syndrome trios. The family-based association was significant between Tourette syndrome and rs4979356 (TDT: χ2 = 4.804, P = 0.033; HRR = 1.75, P = 0.002; HHRR = 1.32, P = 0.027), and transmission disequilibrium was suspected for rs4979357 (TDT: χ2 = 3.969, P = 0.053; HRR = 1.84, P = 0.001; HHRR = 1.29, P = 0.044). No statistically significant allele transfer was found for rs7868992 (TDT: χ2 = 2.177, P = 0.158). Although the TDT results did not remain significant after applying the conservative Bonferroni correction (p = 0.005), the significant positive HRR analysis confirmed the possibility of showing transmission disequilibrium, which provides evidence for an involvement of COL27A1in the development of TS. However, these results need to be verified with larger datasets from different populations.