TNFRSF11B and Osteopenia: A recent study in Spanish postmenopausal women pointed out that patients with T allele and TT genotype of CD40 rs1883832 C > T have decreased CD40 expression and lowered bone mineral density (BMD) at femoral neck and spine sites, leading to the reduced expression of osteoprotegerin (OPG), thereby increasing the susceptibility to osteopenia or osteoporosis [33].