Nucleotide changes around the splicing acceptor of intron 24 in the factor VIII gene and its impact on splicing.
Nucleotide 6724 of the factor VIII gene harbors a polymorphism of low frequency. A report from Taiwan claimed that 97.9% of the 83 alleles examined were of the A nucleotide at this position, which is quite different to the data from Western populations. Furthermore, this nucleotide is the start of exon 25, located in juxtaposition to the splicing acceptor of intron 24. We wonder if the nucleotide change at this location might have any effect on the splicing process of pre-mRNA. Using genomic DNA with direct sequencing of the polymerase chain reaction-amplified intron 24/exon 25 junction site, we found that 59 of the 60 patient samples were of the GTG sequence at nucleotides 6724-6726. The polymorphism is similar between populations in Taiwan and Western countries. The sequence of intron 24 around the splicing acceptor was always TCCAACTCTATTGCCCTCAG (-20 to -1), except for one hemophiliac patient who had a mutation in which the absolute consensus AG doublet of the intron 24 splicing acceptor changed to the AA dinucleotide. Owing to the mutation, exon 24 was erroneously spliced to exon 26, and exon 25 was skipped. This finding further testifies to the importance of the invariant AG dinucleotide in the example of the factor VIII gene.
Gau
Jyh-Pyng
JP
Division of Hematology, Department of Medicine, Taipei Veterans General Hospital and National Yang-Ming University School of Medicine, Taipei, Taiwan. jpgau@vghtpe.gov.tw
Chen
Chih-Cheng
CC
Hsu
Hui-Chi
HC
Ho
Chao-Hung
CH
Chau
Wing-Keung
WK
You
Jie-Yu
JY
Yu
Yuan-Bin
YB
D017398:Alternative Splicing / Q000235:genetics*; D001483:Base Sequence; D005169:Factor VIII / Q000235:genetics*; D005260:Female; D017353:Gene Deletion; D006467:Hemophilia A / Q000235:genetics; D006801:Humans; D007438:Introns / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods; D011110:Polymorphism, Genetic / Q000235:genetics*; D012322:RNA Precursors / Q000378:metabolism; D013624:Taiwan
D012322:RNA Precursors; D005169:Factor VIII