An HLA-B null allele (B*0808N) caused by a nucleotide deletion in exon 3, found in the family of a bone marrow transplant recipient

We have identified a variant HLA-B allele, B*0808N, segregating through two generations of healthy individuals, whilst HLA typing the family of a bone marrow patient. Serological typing identified a disparity between the fath er (Al, A3 B7 DR7) and the brother (Al, H2 B56 DR1, DR7) of the patient. Lo w/medium resolution polymerase chain reaction using sequence-specific prime rs (PCR-SSP) revealed a B*08 allele undetectable by serological methods. Hi gh resolution DNA typing by polymerase chain reaction-sequencing based typi ng (PCR-SBT), revealed a nucleotide deletion at position 131 (C) in exon 3, the only difference between the new allele and B*0801. The deletion result s in a frame shift in the protein coding sequence, introducing a premature termination codon (TGA) in exon 4. Although a B*08 allele is present in the se individuals, the deletion prevents correct expression of the antigen on the cell surface.