TGFB1 and ossification of the posterior longitudinal ligament of the spine: Kamiya et al. firstly disclosed the possible association between a TGFβ1 SNP (rs1800470) and OPLL in a candidate gene association study involving 46 Japanese patients and 273 control subjects [98], but this association was not confirmed by Han et al. in a candidate gene association study of 98 Korean patients and 200 control subjects [105].