Investigation of variants within the COL27A1 and TNC genes and Achilles tendinopathy in two populations.

The TNC gene has previously been associated with Achilles tendinopathy (AT) in a South African population. The aims of this study were (i) to investigate the association of single nucleotide polymorphisms within the TNC gene, and the additional candidate gene, COL27A1, with AT in two populations, and (ii) to identify if there is a risk haplotype for AT in both populations. Three hundred and thirty nine healthy control participants (CON) and 179 participants clinically diagnosed with AT (TEN) from South Africa and Australia, were genotyped for variants: rs4143245, rs1249744, rs753085, rs946053 (COL27A1) and rs13321, rs2104772, rs1330363 (TNC). Haplotypes were inferred using the genotype data. The rs2104772 (p = 0.017) and rs1330363 (p = 0.020) variants within TNC showed a significant allele association with AT. The GCA haplotype (rs946053-rs13321-rs2104772) occurred significantly more frequently in TEN participants compared to CON (27% vs. 18%; p = 0.019). This study further implicates the genomic region containing the TNC and COL27A1 genes in influencing risk of AT, and maps the potential risk allele to a genetic interval flanked by rs946053 and rs2104772. This region may have functional effects on the transcription, structure and properties of tenascin-C and the alpha-1 chain of type XXVII collagen.