ORGANIZATION OF THE HUMAN-IMMUNOGLOBULIN LAMBDA-LIGHT-CHAIN LOCUS ON CHROMOSOME 22Q11.2

The maps of the human immunoglobulin heavy-chain and kappa light-chain loci have recently been completed, We have now completed a map of the human lambda locus (IGL) located on chromosome 22q11.2. We mapped 52 V-lambda genes from 10 V-lambda families and 7 J(lambda) and C-lambda genes on a 1140 kb contig constructed from eight YACs and 129 cosmid c lones, The V-lambda genes are arranged within 800 kb, Genes of the dif ferent V-lambda families are organized in three clusters, V-lambda II and III families (cluster A); V-lambda I, V, VII and IX families (clus ter B); V-lambda IV, VI, VIII and X families (cluster C), in contrast to the dispersed organization of the different V-H and V(k)appa famili es within the human V-H and V-kappa loci, We note that the most freque ntly used V-lambda families (V-lambda II and III) are proximal to the J(lambda) and C-lambda genes, The VpreB gene, encoding part of the sur rogate light chain, the GGT2 gene and the BCRL4 pseudogene were also m apped within the lambda locus.