[Genetics of insulin-dependent juvenile diabetes]

Since the works of Singal and al. and Nerup and al., an increase in B 8, B 15 and B 18 antigens has been found in Insulin Dependent Diabetes. Thomson and al., Rubinstein and al. and the authors of this paper have shown an stronger association with DRw 3 and DRw 4 antigens. We investigated the genetic predisposition to juvenile diabetes in 22 families of 48 cases and 96 members. The study of one affected child in each family showed that DRw 3 was found in 63,63% and DRw 4 in 59,59% (healthy 16,22%)--RR = 9,0 and 7,49. The hypothesis of overdominance proposed by Nerup can be confirmed by our data, when I.D.D.M. share two different alleles (DRw 3 and DRw 4). 3 particular haplotypes with linkage imbalance are therefore observed in our series: B 8-Bf S-DRw 3, B 15-Bf F-DRw 4 and B 8-Bf F 1-DRw 3. Our date show a excessive transmission of the diabetic haplotype by parents who are either diabetics or carriers of the gene.