In Caucasian populations, evidence shows that the hMSH5 rs28381349 (L85F)/rs28399984 (P786S) and hMSH5 intron 12 SNP rs3131378 are enriched in patients with IgA deficiency (IgAD) and common variable immune deficiency (CVID) [21]. Here, MSH5 is linked to selective IgA deficiency disease.