IgA2 genotyping by polymerase chain reaction (PCR) using allele-specific amplification primers.

A method of genotyping IgA2 alleles in the human immunoglobulin alpha 2 heavy chain constant region (C alpha 2 gene) was developed by using the polymerase chain reaction (PCR). By this method, the genotype was determined by discriminating base substitution in the 3'-flanking region of alleles, A2m*1 and A2m*2, which manifest A2m serum types, by nested PCR using allele-specific primers. Three types, IgA2*1/IgA2*1, IgA2*2/IgA2*1, and IgA2*2/IgA2*2, were detected from DNA extracted from lymphocytes. Genotyping was possible from 100 pg of DNA by this method. The estimated allele frequency in 318 Japanese subjects was 0.561 for IgA2*1 and 0.439 for IgA2*2. Analysis of 29 cases of paternity tests suggested that the data follow Mendel's law of inheritance. This genotype could also be detected in whole blood, blood stains, saliva stains, and various organs and tissues. These results suggest the usefulness of the present method for paternity testing and individual identification in forensic medicine.