Submitted February 6, 2002
Accepted March 20, 2002
Molecular genetic analysis for the B3 allele
Lung-Chih Yu, Yuh-Ching Twu, Ming-Lun Chou, Ching-Yi Chang, Chia-Ying Wu, and Marie Lin*
Transfusion Medicine Laboratory, Department of Medical Research, Mackay Memorial Hospital, Taipei, Taiwan
Transfusion Medicine Laboratory, Department of Medical Research, Mackay Memorial Hospital, Taipei, Taiwan; Immunohematology Reference Laboratory, Mackay Memorial Hospital, Taipei, Taiwan
* Corresponding author; email: marilin{at}ms2.mmh.org.tw.
Molecular genetic analysis of 14 samples from unrelated individuals with the B3 phenotype is reported here. Two different molecular changes in the blood group B gene were observed. One case was demonstrated to possess a 247G
A mutation, which predicts an Asp83Tyr alteration. The B genes of the other 13 cases were shown to have a GA mutation at the +5 nucleotide of intron 3 (IVS3+5GA). RT-PCR analysis showed that the complete exon 1~7 B transcript was absent and transcripts with exon 3 skipped were present instead in the RNA sample from the B3 individual with the IVS3+5GA mutation. The result shows that the IVS3+5GA mutation destroys the conserved sequence of the splice donor site and leads to the skipping of exon 3 during mRNA processing. The B3 transcript without exon 3 predicts a B transferase product which lacks 19 amino acids in the N-terminal segment.
