title: [Polymorphism of C4 and factor B in type I diabetes].
abstract: The haplotypic frequencies of the fourth component of complement (C4) and factor B (Bf) have been determined in 44 Alsatian type 1 diabetics. An increased frequency of the rare allele Bf F1 (9.1% vs 1.5%) and of the silent alleles of C4 (C4 AQO: 21.6% vers 15.5% -C4 BQO: 29.6% vs 16.0%) was observed in diabetics in comparison to the general population of the same geographic area. A complete HLA haplotype determination has been obtained in 24 type 1 French diabetics. Three haplotypes were associated with the diabetic susceptibility: HLA-A30 CW5 B18 BfF1 C4A3BQO DR3 (18.75% vs 0.86%), HLA-A1 CW7 B8 BfS C4AQOB1 DR3 (15.58% vs 4.17%), HLA-A2 CW3 BW62 BfS C4A3B3 DR4 (6.25% vs 0.45%). The authors suggest that the silent alleles of C4 could modulate the expression of the diabetic susceptibility genes by lowering of the serum C4 hemolytic activity.
mesh_terms: D000483:Alleles; D003181:Complement C4 / Q000235:genetics*; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics*; D006680:HLA Antigens / Q000235:genetics*; D015235:HLA-B Antigens; D006239:Haplotypes; D006801:Humans; D010375:Pedigree; D011110:Polymorphism, Genetic
chemical_list: D003181:Complement C4; D006680:HLA Antigens; D015235:HLA-B Antigens; C048259:HLA-Bf antigen
vernacular_title: Polymorphisme du C4 et du facteur B dans le diabète de type I.