TNFRSF13B and Immunodeficiency: Earlier studies also raised the possibility that joint inheritance of TNFRSF13B mutations and HLA-associated susceptibility haplotypes might facilitate the development of immune deficiency and help explain variations in penetrance: Salzer et al. (1) reported that of 13 affected individuals, 9 had inherited HLA*B8 and 6 had inherited HLA*B44.