MHC supratypes as markers of null and defective C4 alleles in a Thai/Chinese population: relevance to disease susceptibility.
Deficiency alleles at the C4 loci within the MHC are associated with autoimmune diseases in Caucasoids and possibly other races. We therefore studied the relationship between relevant C4 alleles and other MHC markers in a random Thai/Chinese population. Over 90 per cent of C4AQO occurs within two supratypes (HLA Aw33, B44, C4AQO, B1, BfS, DR7 and Aw33, B17, C4AQO, B1, BfF DR x where x is an unassigned DR antigen). These two supratypes have minimum population frequencies of 6 and 3 per cent, respectively. Almost 70 per cent of C4BQO is contained within the supratype HLA Aw33 (11), B17, C4A3, BQO, BfS, DR3. At least 8 per cent of the Thai/Chinese population bear this supratype. Essentially all subjects with C4A6 also have HLA A1, B17, C4B1, BfS, and DR7. Approximately 6 per cent of Thai/Chinese have this supratype which is also found in Caucasoids. Partial C4 deficiency is common in Thai/Chinese as well as Caucasoids, can be inferred from examination of HLA phenotypes and may contribute to susceptibility to some diseases.
D000483:Alleles; D001327:Autoimmune Diseases / Q000235:genetics*; D002681:China / Q000208:ethnology; D003181:Complement C4 / Q000235:genetics*; D004198:Disease Susceptibility; D005006:Ethnicity; D005787:Gene Frequency; D005819:Genetic Markers; D006680:HLA Antigens / Q000235:genetics*; D006801:Humans; D013785:Thailand
D003181:Complement C4; D005819:Genetic Markers; D006680:HLA Antigens