Clustered arrangement of immunoglobulin lambda constant region genes in man

The immunoglobulin lambda light chain locus of man contains six lambda-like genes arranged tandemly on a 50-kilobase segment of chromosomal DNA. THe sequences of three of these genes correspond to three known non-allelic lambda chain isotypes: Mcg, Ke-Oz- and Ke-Oz+. They surround a highly polymorphic and evidently unstable region that is repeatedly deleted when cloned in Escherichia coli. Three additional, but as yet unlinked, lambda-like sequences have also been cloned, suggesting that the lambda genes form an unexpectedly large family within the human genome.