TNFRSF13B and agammaglobulinemia: Two of the nine putative disease genes at ancestry-heterogeneous loci (category 3), TNFRSF13B and IKZF1, are causal genes for human primary immunodeficiency disorders (PID)32 presenting with primary antibody deficiencies (PADs), whereas none of the disease genes at the putative ancestry-heterogeneous loci (category 2, 0/22; Fisher exact test P = 0.07) or the ancestry-shared loci (category 1, 0/120; Fisher exact test P = 0.004) are known to cause PADs in humans.