COL6A1 and ossification of the posterior longitudinal ligament of the spine: A candidate gene association study in 97 Japanese DISH patients and 298 controls, and in 96 Czech DISH patients and 96 controls, revealed that a COL6A1 SNP (rs35796750) already identified in OPLL was also associated with DISH in Japanese patients, although this association was undetected in Czech patients [76, 102].