title: Identification of the null HLA-A2 allele, A*0232N.
abstract: We have identified a null HLA-A*02 allele, HLA-A*0232N, by using a combination of serology, flow cytometry, polymerase chain reaction using sequence-specific primers (PCR-SSP) and full-length sequencing. The null HLA-A2 allele was identified in an Asian individual originally typed by serology as an apparently homozygous HLA-A3, B51. Subsequent genotyping by PCR-SSP identified the genotype as HLA-A*0201, *0301, B*51, Cw*1402. The serological type and lack of detectable HLA-A2 was confirmed using monoclonal antibody typing reagents. Flow cytometry studies failed to identify any cell surface HLA-A2 expression on the patient's peripheral blood lymphocytes. Genotyping using a PCR-SSP set designed to detect null alleles revealed the mutation had not been previously described. Full-length sequencing of the allele identified an allele which was subsequently named HLA-A*0232N. This allele is identical to HLA-A*0201 except for a novel point mutation (T for C) at position 493 which creates a premature stop codon. The sequencing enabled the development of a monospecific A*0232N PCR-SSP reaction which was used to screen 973 DNA samples: no further examples of A*0232N were identified.
authors.affiliation: Transplantation Immunology, Nuffield Department of Surgery, Oxford Transplant Centre, Churchill Hospital, UK. mbunce@hgmp.mrc.ac.uk
authors.forename: M
authors.initials: M
authors.lastname: Bunce
authors.forename: J
authors.initials: J
authors.lastname: Procter
authors.forename: P P
authors.initials: PP
authors.lastname: Dunn
authors.forename: S
authors.initials: S
authors.lastname: Day
authors.forename: J
authors.initials: J
authors.lastname: Ross
authors.forename: K I
authors.initials: KI
authors.lastname: Welsh
mesh_terms: D000483:Alleles; D001483:Base Sequence; D004252:DNA Mutational Analysis; D017931:DNA Primers / Q000737:chemistry; D005260:Female; D005434:Flow Cytometry; D005838:Genotype; D015789:HLA-A2 Antigen / Q000235:genetics*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000601:surgery; D016030:Kidney Transplantation; D008969:Molecular Sequence Data; D017354:Point Mutation; D016133:Polymerase Chain Reaction
chemical_list: D017931:DNA Primers; D015789:HLA-A2 Antigen