A novel HLA-B*40 allele and novel exon 1 sequences of two B*40 alleles identified in potential marrow donors

Sequence-specific oligonucleotide probe hybridization and sequence-specific primer polymerase chain reaction (PCR) typing suggested the presence of va riants of HLA-B*40 in three individuals. Two were part of 3,500 potential m arrow donors being screened for the National Marrow Donor Program, while th e third was a clinical specimen. PCR products encompassing HLA-B locus exon s 1 through 3 were prepared and subcloned, In one individual, a native of t he Pacific Islands, sequencing revealed a novel HLA-B*40 allele (B*4023), I n two other individuals, a previously unknown exon 1 sequence was determine d for KLA-B*4016 (ethnicity unknown) and B*4020 (Hispanic). These findings further illustrate the substantial genetic variation present at the HLA-B l ocus within human populations.