A non-synonymous TNFRSF11A variation increases NFkB activity and the severity of Paget's disease

Mutations in the SQSTM1 gene were identified as a common cause of Paget's disease of bone (PDB) but experimental evidencedemonstrated that SQSTM1 mutation is not sufficient to induce PDB in vivo. Here, we identified two nonsynonymous single nucleotidepolymorphisms (SNPs) (C421T, H141Y and T575C, V192A) in the TNFRSF11A gene, associated with PDB and with the severity ofphenotype in a large population of 654 unrelated patients that were previously screened for SQSTM1 gene mutations. The largest effectwas found for the T575C variant, yielding an odds ratio of 1.29 (p¼0.003), with the C allele as the risk allele. Moreover, an even moresignificant p-value (p¼0.0002) was observed in the subgroup of patients with SQSTM1 mutation, with an odds ratio of 1.71. Interestingly,patients with the C allele also showed an increased prevalence of polyostotic disease (68%, 53%, and 51% in patients with CC, CT, and TTgenotypes, respectively; p¼0.01), as well as an increased number of affected skeletal sites (2.9, 2.5, and 2.0 in patients with CC, CT, and TTgenotypes, respectively, p¼0.008). These differences increased when analyses were restricted to cases with SQSTM1 mutation. In humancell lines, cotrasfection with mutated SQSTM1 and TNFRSF11AA192 produced a level of activation of NFkB signaling greater thancotrasfection with wild-type SQSTM1 and TNFRSF11AV192, confirming genetics and clinical evidences. These results provide the firstevidence that genetic variation within the OPG/RANK/RANKL system influences the severity of PBD in synergistic action with SQSTM1gene mutations