LEPR and ossification of the posterior longitudinal ligament of the spine: It was found that hyperleptinemia, hyperinsulinemia, and the female sex are associated with the development of OPLL [13], Another study, in 2005, demonstrated the possibility of polymorphisms of the nucleotide pyrophosphatase gene and the leptin receptor gene, predisposing to an increased frequency and severity of OPLL [14].