HIGH-RESOLUTION DNA TYPING IN IMMUNOGLOBULIN-A DEFICIENCY CONFIRMS A POSITIVE ASSOCIATION WITH DRB1-ASTERISK-0301, DQB1-ASTERISK-02 HAPLOTYPES

Selective immunoglobulin A (IgA) deficiency, the most common form of p rimary immunodeficiency, is related to the HLA genes. Previous studies demonstrated associations with particular HLA-DR-DQ haplotypes and a neutral amino acid at position 57 of the DQ beta chain was implicated in the susceptibility to selective IgA deficiency. In this study we re analyzed the reported findings by high-resolution DNA typing of the lo ci DRB1, DQB1 and DQA1. We compared the typing results of 74 IgA-defic ient individuals, detected by screening of blood donors, with those ta ken from 111 healthy controls. Results confirmed a strong positive ass ociation with DRB10301, DQB1*02 and a negative association with DRB1* 1501, DQB10602. Considering the molecular interactions between HLA cl ass II alleles and the peptides bound we conclude that the amino acid at position 57 of the DQ beta chain may contribute to the susceptibili ty to selective IgA deficiency, but not determine it. An extended stat istical analysis strengthened the hypothesis that selective IgA defici ency might be communicated by the distinct haplotype DRB10301, DQB1*0 2.