Km Typing with PCR: Application to Population Screening

The immunoglobulin kappa light chain (IgK) locus may play a significant role in the pathology of both infectious and autoimmune diseases. Most of the work on IgK genetics has been conducted using immunological techniques for allelic typing and sequence analysis. This is restricted by availability of reagents and can be both expensive and time-consuming. PCR primers were designed to amplify the kappa constant gene (Ck), and four allele-specific oligonucleotides (ASOs) were used to distinguish the alleles in the amplified PCR products. Direct sequencing of PCR products was performed to confirm that the primers specifically amplified the Ck region and the ASOs differentiated the Km alleles. Sequencing of an average of 209 nucleotides of DNA from 50 individuals revealed no variation except at codon 191, which is known to be involved in a frequent polymorphism. An analysis of 347 different individual DNAs from 10 human populations was conducted to determine Km allelic frequencies within these populations and to apply this type of data collection to population studies.