TNFRSF13B and peripheral arterial disease: Moreover, the observation that the risk of developing PAD in any given offspring in a family with a variant in TNFRSF13B and a diagnosed patient with PAD is close to 25% (i.e., 50% of TNFRSF13B mutation carriers) suggests the presence of additional modifying genes in patients (4, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27).