ABO transcript structures of the group B individual and the B₃ individual with the IVS3 + 5G → A mutation analyzed by RT-PCR.

(A) RT-PCR results obtained from the RNA samples of the group B individual and the B₃ individual with the IVS3 + 5G → A mutation. The RT-PCR products were analyzed by 3.0% agarose gel electrophoresis. The results obtained from the common B and the B₃ samples are shown in lane B and lane B₃, respectively. Lane M shows the molecular mass standards of the 100-bp ladder. The 2 products (559 and 424 bp) from the group B sample were demonstrated to be amplified from the complete BcDNA structure and from the B cDNA structure without the exon 6 region, respectively. The 2 smaller products (502 and 367 bp) from the B₃ sample were shown to be amplified, respectively, from the B cDNA with exon 3 skipped and from the B cDNA with exon 3 and exon 6 skipped. (B) Sequencing result of the 502-bp product obtained from the B₃ RNA sample. The 502-bp fragment obtained from the B₃ RNA sample was eluted from the agarose gel and sequenced. It was demonstrated to have the exon 2–exon 7 structure but without the exon 3 region. The linkage of exon 2 and exon 4, indicating the skipping of exon 3, is shown.