Variable amplification of immunoglobulin λ light-chain genes in human populations

Abstract

The human λ immunoglobulin locus displays a series of restriction fragment length polymorphisms that are readily detected in small populations of normal individuals1. Similar polymorphisms appear in populations of wild mice, suggesting that the λ locus1–5 is subject to rapid variation within a single species6. Here we show that the polymorphisms seen in the human λ locus seem to have arisen from unequal meiotic crossing over, altering the number of λ genes from as few as six to as many as nine per haploid genome. This expansion and contraction in the number of human λ genes is significant in that it may affect an individual's capacity to produce variation among λ light chain genes.