ENPP1 and ossification of the posterior longitudinal ligament of the spine: Prospective phenotyping of 20 survivors of GACI further supports an association between ENPP1 and OPLL, in which eight patients with homozygous or compound heterozygous ENPP1 pathogenic variants who developed ARHR2 after surviving GACI were found with enthesopathies in the Achilles tendons or elbow joints, including in relatively young patients, aged 26 and 25 years [40, 41•].