IDENTIFICATION OF A NOVEL HLA-CW*07 ALLELE, CW*0713, AND SUBSEQUENT MISMATCHING IN AN UNRELATED BONE MARROW TRANSPLANT
JH Moses, J Downes, W McClenahan, W Greville and H Dunckley Tissue Typing Services, Australian Red Cross Blood Service, Sydney, Australia.

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A new HLA-Cw*07 allele, Cw*0713 was identified in a patient with aplastic anaemia and their mother, the patient subsequently received an unrelated bone marrow transplant mismatched at this C locus allele. During routine Sequence Specific Primer (SSP) typing of the patient, an HLA-Cw locus typing pattern was observed which did not fit any combination of known homozygous or heterozygous HLA-Cw alleles. SSP typing of the patient’s parents revealed the mother also had a unique typing pattern and that the new allele appeared to be closely related to the HLA-Cw*07 group of alleles. Exons 2 and 3 of the novel HLA-Cw allele from mother and patient were cloned and sequenced and the presence of a new Cw locus allele was confirmed. The new allele, officially named as Cw*0713, is most closely related to Cw*0702. The only difference is a single base substitution of C to T at nucleotide 419 in exon 3 resulting in a change of serine to phenylalanine at amino acid residue 116 which maps to the beta pleated sheet in the bottom of the peptide binding groove.

The patient received a bone marrow transplant from an unrelated donor, matched at HLA-A, B, DRB1, DRB3, DRB4 and DQB1 but mismatched only by Cw*0702 in the donor and Cw*0713 in the patient.