An HLA-B null allele (B*1526N) with a stop codon in exon 3 generated by a point mutation.
An HLA-B null allele was identified in a Japanese family during histocompatibility testing for bone marrow transplantation. The propositus was a healthy Japanese woman with three children, and her parents were cousins. Serological HLA typing of the family members indicated that the propositus was homozygous for the A24-Cw4-B blank (B null)-DR4.2-DQ3 haplotype. Total RNA was extracted from peripheral blood of the propositus was converted to first-strand cDNA using reverse transcriptase. The cDNA was amplified by the polymerase chain reaction (PCR) using HLA-B locus-specific primers. The PCR product showed no change in size upon polyacrylamide gel electrophoresis (PAGE) compared to that of normal controls, suggesting that HLA-B gene mRNA was normally expressed. The nucleotide sequence of the cDNA was the same as that of B*1501 except at nucleotide 369 or codon 123, where C was replaced with A; TAC encodes Tyr whereas TAA is a stop codon. This point mutation may have truncated the HLA-B molecule of the propositus, resulting in the negative results we obtained with anti-HLA-B sera.
Mine
H
H
Kyoto Red Cross Blood Center, Japan.
Ishikawa
Y
Y
Hojo
M
M
Imashuku
S
S
Tokunaga
K
K
Juji
T
T
Saji
H
H
Yokoyama
S
S
D000328:Adult; D000483:Alleles; D001483:Base Sequence; D003062:Codon / Q000235:genetics*; D003241:Consanguinity; D016384:Consensus Sequence; D004252:DNA Mutational Analysis; D018076:DNA, Complementary / Q000235:genetics; D005091:Exons / Q000235:genetics*; D005260:Female; D005805:Genes, MHC Class I; D015235:HLA-B Antigens / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D010375:Pedigree; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D013728:Terminator Regions, Genetic / Q000235:genetics*
D003062:Codon; D018076:DNA, Complementary; D015235:HLA-B Antigens