Association between EcoRI fragment-length polymorphism of the immunoglobulin lambda variable 8 (IGLV8) gene family with rheumatoid arthritis and systemic lupus erythematosus

The human immunoglobulin lambda variable 8 (IGLV8) subgroup is a gene famil y containing three members, one of them included in a monomorphic 3.7-kb Ec oRI genomic fragment located at the major lambda variable locus on chromoso me 22q11.1 (gene IGLV8a, EMBL accession No. Z73650) at 100% frequency in th e normal urban population. The second is a polymorphic RFLP allele included in a 6.0-kb EcoRI fragment at 10% frequency, and the third is located in a monomorphic 8.0-kb EcoRI fragment at 100% frequency, the last being transl ocated to chromosome 8q11.2 and considered to be an orphan gene. Our Southe rn blot-EcoRI-RFLP studies in normal individuals and in patients with rheum atoid arthritis (RA) or with systemic lupus erythematosus (SLE), using a sp ecific probe for the IGLV8 gene family (probe pVL8, EMBL, accession No. X75 424), have revealed the two monomorphic genomic fragments containing the IG LV8 genes, i.e., the 3.7-kb fragment from chromosome 22q11.1 and the 8.0-kb fragment from 8q11.2, both occurring at 100% frequency (103 normal individ uals, 48 RA and 28 SLE patients analyzed), but absence of the 6.0-kb IGLV8 polymorphic RFLP allele in all RA or SLE patients. As expected, the frequen cy of the 6.0-kb allele among the normal individuals was 10%. These finding s suggest an association between the absence of the 6.0-kb EcoRI fragment a nd rheumatoid arthritis and systemic lupus erythematosus.