Identification of a new HLA-DRB1 allele (DRB1*0318) in three members of a Caucasian Spanish family.

This communication reports the identification of a new allele HLA-DRB103 in three members of a Caucasian Spanish family. The new allele has been officially named HLA-DRB10318 by the World Health Organization Nomenclature Committee. The exon 2 sequence of this new allele is identical to that of DRB103011 except for the first nucleotide of codon 45. The nucleotide change (C replacing G) leads to the amino acid substitution of glycine to arginine (GGG-->CGG) at position 45. This position of the beta1 domain shows very little polymorphism among DRB1 alleles (nucleotide changes at this position have only been reported for DRB11436 and DRB10105) and locates in the vicinity of the highly polymorphic position 47, which is a constituent of the groove's pocket interacting with the amino acid position 7 of the antigen peptide. The familial study showed that the new allele was maternally transmitted into the HLA-A3002, -B1801, -Cw0501, -DRB10318, -DRB30202, -DQB10201 haplotype. Interestingly, the two siblings of the family, which were HLA identical and suffered of insulin-dependent diabetes mellitus (IDDM), were carriers of the two HLA haplotypes (DRB103/DQB10201 and DRB104/DQB10302) reported as susceptibility markers to IDDM in Caucasians.