Identification of a novel HLA-Cw*05 allele, Cw*0503

HLA-Cw*05 is one of the least polymorphic subgroups of HLA-C; so far only t wo alleles, namely Cw*0501 and Cw*0502, have been reported. We report here the identification of a third allele, Cw*0503, in a Caucasian individual. C w*0503 is closely related to Cw*0501 with only six nucleotide substitutions clustering over a fragment of 48 nucleotides at the beginning of exon 4. A ll these six substitutions at the same positions have been found only in HL A-B*44 alleles, suggesting that Cw*0503 is a result of recombination betwee n Cw*0501 and one of B*44 alleles.