We performed a backward stepwise variable regression on duration of infection before IgGSD diagnosis using these independent variables: sex; age at diagnosis; diabetes; autoimmune condition(s); atopy; allergy; corticosteroid use; body mass index; serum Ig isotype levels; blood lymphocyte subsets; three HLA-A and -B haplotypes; and referring physician specialties. This evidence concerns the gene HLA-A and infection.