The three haplotypes in COL5A2 that were the most significant were equivalent in their association with PTD: G-A-G at rs6434322-rs10165260-rs7420331 (p = 0.001) with an RR of 0.49 (CI: 0.31, 0.77), A-A-G at rs3923384-rs6434317-rs6434322 (RR = 0.49, CI: 0.31, 0.77) and A-G-A at rs6434317-rs6434322-rs10165260 (RR = 0.49, CI: 0.31, 0.77) (Table 7). This evidence concerns the gene COL5A2 and Bjornstad syndrome.