Chromosomal location of the human immunoglobulin lambda variable 8 (IGLV8) gene family outside the major λ locus on chromosome 22q11.2

Abstract

Physical mapping of the human immunoglobulin λ locus (IGL) on chromosome 22q11 has shown the existence of at least 52 variable region gene segments. These Vλ genes are associated with EcoRI fragments detectable in Southern blots of genomic DNA samples. The current physical map of the IGL locus includes a unique Vλ8 gene (IGL8a, accession no. Z73650) in a 3.7 kb EcoRI fragment. However, our Southern blot- EcoRI-restriction fragment length polymorphism studies on the Brazilian population using a specific probe for the Vλ8 gene (pVL8 probe) have revealed the presence of two additional fragments bearing Vλ8 sequences (8.0 kilobase (kb) at 100% frequency and 6.0 kb at 10% frequency). We have used human/rodent somatic cell hybrid DNAs to locate these new Vλ8 genes outside the major locus on chromosome 22q11.2. Polymerase chain reactions using specific primers for the IGLV8a gene on the somatic hybrid panel showed that chromosome 8 (besides 22q11) also comprises Vλ8 sequences. This finding represents evidence for the dispersion of the human IGLV8 gene family outside the major locus (orphan genes).