COL6A1, the candidate gene for ossification of the posterior longitudinal ligament, is associated with diffuse idiopathic skeletal hyperostosis in Japanese

Study Design. Genetic screening of collagen 6A1 gene (COL6A1) in patients with diffuse idiopathic skeletal hyperostosis (DISH) recruited in Japan and the Czech Republic. Objective. To investigate allelic associations between DISH and nucleotide variants of COL6A1. Summary of Background Data. DISH is a skeletal hyperostotic disease characterized by ligamentous ossification of the anterolateral side of the spine. Ossification of the posterior longitudinal ligament (OPLL) is a related disorder with DISH, and COL6A1 was identified as a susceptibility gene to OPLL. COL6A1 was examined for susceptibility in DISH patients from Japan and the Czech Republic. Methods. Seven single nucleotide polymorphisms of COL6A1 were genotyped by direct sequencing. The allele frequencies were compared between 97 Japanese DISH patients and 298 Japanese controls, and between 96 Czech DISH patients and 96 Czech controls by chi(2) test. Results. The intron 32 (-29) single nucleotide polymorphisms of COL6A1 was significantly associated with the Japanese DISH patients (chi(2) = 9.33; P = 0.0022), but not with the Czech DISH patients. Conclusions. Because COL6A1 could be a susceptibility to the occurrence of DISH and OPLL in the Japanese population, we consider that COL6A1 could be responsible for the hyperostotic state, leading to ectopic bone formation in the spinal ligament.