title: HLA and C4 polymorphism in diabetic microangiopathy.
abstract: We have reported an increased frequency of the rare B3 allotype of the fourth component of complement (C4B3) in insulin-dependent diabetics, especially in those with microangiopathy. This study has now been expanded--20 of 106 subjects with microangiopathy and 9 of 116 without possessed the C4B3 allotype (p less than 0.02). C4B3 is said to be in linkage disequilibrium with HLA-DR4. HLA typing was performed on 94 of these patients, 52 with and 42 without microangiopathy. There was no significant difference in the frequency of DR4 (62 vs 50%), DR3 (65 vs 52%), B8 (40 vs 40%) or B15 (32 vs 19%) respectively between these 2 groups. These results confirm an HLA-linked predisposition to microangiopathy, but do not determine whether the primary association is with C4B3, DR4 or another gene with which they are in linkage disequilibrium.
mesh_terms: D003181:Complement C4 / Q000235:genetics*; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics*; D003925:Diabetic Angiopathies / Q000235:genetics*; D005787:Gene Frequency; D006681:HLA-D Antigens / Q000235:genetics*; D006684:HLA-DR Antigens / Q000235:genetics*; D015804:HLA-DR4 Antigen; D006801:Humans
chemical_list: D003181:Complement C4; D006681:HLA-D Antigens; D006684:HLA-DR Antigens; D015804:HLA-DR4 Antigen