The human immunoglobulin variable lambda locus IGLV9 gene is a monomorphic marker in the urban Brazilian population.

The physical map of the human immunoglobulin variable lambda locus (IGLV) located on chromosome 22q11.1-q11.2 shows the existence of 52 functional V-lambda genes distributed among three V-clusters. The IGLV9S1 gene, located in the V-B cluster, is a sequence tagged site and is a useful marker for restriction fragment length polymorphism (RFLP) population studies. The V-lambda genes are associated in the genome with EcoRI fragments detectable in Southern blots of genomic DNA samples. We have analysed DNA samples of an urban Brazilian population by Southern-EcoRI-RFLP using an IGLV9 gene segment. Among 75 unrelated individuals analysed, we detected a single 6.0 kb EcoRI fragment containing the IGLV9 gene at 100% frequency. Reverse transcription followed by polymerase chain reaction (RT-PCR) of peripheral blood leukocyte total RNA from unrelated individuals showed that IGLV9S1 is a functional gene contributing to the B lymphocyte repertoire. These data represent evidence for monomorphism of the IGVL9S1 gene in this urban population. We demonstrate that IGLV9S1 is a functional single copy gene and is an important marker in the IGLV locus.