HLA ANTIGENS IN ITALIAN TYPE-1 DIABETIC-PATIENTS - ROLE OF DR3 DR4 ANTIGENS AND BREAST-FEEDING IN THE ONSET OF THE DISEASE/

HLA-A, B, C, DR and DQ typing was performed in 381 Italian insulin-dep endent diabetic patients and in 905 normal Italian subjects. The diabe tic patients had significantly higher frequencies of HLA-Cw7, B8, B18, DR3, DR4, DQw2 and DQw3 and significantly lower frequencies of HLA-B1 7, Bw51, DR2, DR7 and DRw11. The frequency of heterozygosity for HLA-D R3/DR4 was significantly higher in patients who developed the disease in the first 2 years of life and DR3+/DR4-, DQw2 and DQw3 alleles were higher in those aged less than 14 years at onset. The HLA-DR4 allele was associated with onset of diabetes in autumn and HLA-B 18 with onse t in Autumn-winter. Diabetic children who were breast fed had a later onset of insulin-dependent diabetes mellitus than those who were bottl e fed but these differences were independent of HLA typing (11.18 +/- 0.72 years vs 9.23 +/- 0.42 years; mean +/- SEM). We conclude that: (1 ) in general, HLA distribution in Italian insulin-dependent diabetic p atients reflects previous data reported in other European and North Am erican populations; (2) HLA-DR3 and DR4 are strongly associated with i nsulin-dependent diabetes in Italy as well, and these alleles seem to predispose to an earlier onset of the disease: and (3) breast feeding may delay the onset of the disease.