Aberrant splicing of intron 1 creates a novel null HLA-B*1501 allele.
A comparison of serological and DNA HLA class I typing data identified a serological "blank" HLA-B15 antigen in a volunteer donor on the bone marrow registry. Isoelectric focusing and Western blot analysis of a cell line established from this individual confirmed that the HLA-B15 antigen is not expressed at the cell surface. Nucleotide sequence analysis of the HLA-B*15 null allele revealed a 10-bp deletion near the 3' end of intron 1, when compared to the normal HLA-B*1501 sequence. All of the HLA-B*15 specific cDNA clones examined retained the intron 1 sequence. Reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot analysis demonstrated that the HLA-B*15 mRNA molecule contained the intron 1 sequence, indicating an inability to efficiently splice out intron 1 from the mRNA transcript. The retention of the mutated intron 1 sequence in the mRNA causes a frameshift and premature termination of translation at the start of exon 2, explaining the HLA-B*1501 null phenotype. Our data predicts that the HLA-B*1501 null allele would express a small truncated protein containing the signal sequence fused to an ORF within intron 1 and terminating (out of frame) just within exon 2.
Curran
M D
MD
Northern Ireland Histocompatibility and Immunogenetics Laboratory, City Hospital, Belfast, UK.
Williams
F
F
Little
A M
AM
Rima
B K
BK
Madrigal
J A
JA
Middleton
D
D
D000483:Alleles; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D001853:Bone Marrow; D015235:HLA-B Antigens / Q000235:genetics*; D059910:HLA-B15 Antigen; D006650:Histocompatibility Testing; D006801:Humans; D007438:Introns; D007525:Isoelectric Focusing; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000737:chemistry; D012042:Registries; D017384:Sequence Deletion; D014019:Tissue Donors
D015235:HLA-B Antigens; D059910:HLA-B15 Antigen; D012333:RNA, Messenger