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 i n three members of a Caucasian Spanish family. The new allele has been offi cially named HLA-DRB1*0318 by the World Health Organization Nomenclature Co mmittee. The exon 2 sequence of this new allele is identical to that of DRB 1*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 pi domain shows very li ttle polymorphism among DRB1* alleles (nucleotide changes at this position have only been reported for DRB1*1436 and DRB1*0105) and locates in the vic inity 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 p eptide. The familial study showed that the new allele was maternally transm itted 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 H LA identical and suffered of insulin-dependent diabetes mellitus (IDDM), we re carriers of the two HLA haplotypes (DRB1*03/DQB1*0201 and DRB1*04/DQB1*0 302) reported as susceptibility markers to IDDM in Caucasians.