A specific defect of procollagen telopeptide lysine hydroxylation in BS and mutations in the gene PLOD2 have been identified (BS type 2); yet, the clinical and radiographic features of PLOD2-associated BS have not been described in detail, and only a large family study showed evidence of linkage to chromosome 17 (designated BS type 1) [6]. The gene discussed is PLOD2; the disease is Bloom syndrome.