HLA antigens and haplotypes in IgA-deficient Brazilian paediatric patients.

In the present study we determined the HLA-A, B and DR antigenic and haplotypic frequencies in unrelated Brazilian Caucasian paediatric patients with IgA deficiency (IgA-D). Out of 17 IgA-D subjects typed for HLA A and B specificities, 12 (71%) presented B8 and/or B14; of 15 patients also typed for HLA-DR specificities, 14 (93%) were positive for at least one of the HLA markers previously reported to be associated with IgA-D, i.e. B8, B14, DR1, DR3 or DR7. The haplotypes B8, DR3, B14, DR1 and B13, DR7 were present in 43, 21 and 14% of the cases, respectively, while they have a frequency in the general population of 2, 2 and 1%, respectively. The concomitant association with the three IgA-associated haplotypes found in our study probably reflects the admixture of European genetic influences present in the Brazilian Caucasian population of São Paulo.