Gene Duplication of C4A in the Lancaster County, Pennsylvania, Old Order Amish: C4A*2A*3 is in Coupling with HLA A3, Cw4, B35, BfF, DR1, GLO2
Eight families (76 individuals) of the Old Order Amish religious isolate of Lancester County, Pennsylvania, were selected for complement phenotype analysis. Gene duplication at the C4A locus was detected in three families. The duplication (C4A*2A*3) was present on the same HLA haplotype in all cases and could be traced to one founder. The phenotype for the two loci of the fourth component of complement (C4A and C4B) were determined by electrophoresis in agarose, immunofixation with anti-C4 antiserum, crossed-gel immunoelectrophoresis, and hemolytic overlay. Factor B (Bf) phenotype was determined by immunofixation. The order of genes in haplotypes is written HLA-A, Cw, B, C4A, C4B, Bf, DR, DQ, GLO.
KeywordsAgarose Electrophoresis Haplo
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