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-DRB1*03 in three members of a Caucasian Spanish family. The new allele has been officially named HLA-DRB1*0318 by the World Health Organization Nomenclature Committee. The exon 2 sequence of this new allele is identical to that of DRB1*03011 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 DRB1*1436 and DRB1*0105) 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-A*3002, -B*1801, -Cw*0501, -DRB1*0318, -DRB3*0202, -DQB1*0201 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 (DRB1*03/DQB1*0201 and DRB1*04/DQB1*0302) reported as susceptibility markers to IDDM in Caucasians.