There were no differences in plasma levels of MMP-13 and RANKL among osteomyelitis patients with the different genotypes of the CTSG. Therefore, mechanisms other than increased MMP-1, -13 and sRANKL might explain the increased susceptibility to osteomyelitis in carriers of the CTSG N125S polymorphism. The gene discussed is TNFSF11; the disease is osteomyelitis.