A nonsense mutation in exon 3 results in the HLA-B null allele B*5127N.

A new HLA-B null allele has been identified within the B51 group by combined serological and molecular typing of an Italian Caucasoid family. Serological data indicated that the proband typed homozygous for A2 and B60. Confirmatory typing using sequence specific oligonucleotide hybridization (SSPOH) detected a second B allele within the B51 group. Allele specific typing (SSP) for B51 subtypes, including the known B5111N allele, was performed, and typing results were consistent with B5101, suggesting the presence of a new null variant. Cloning and sequencing of this allele identified a B5101 variant with a nonsense mutation in exon 3. This new null allele has been designated B*5127N. The combined use of serologic and DNA-based typing methods facilitates the identification of null and low-expression alleles. An overview of null alleles of class I HLA is presented.