A single-base change at a splice site in a beta 0-thalassemic gene causes abnormal RNA splicing.
We have studied the structure and transcription of a cloned human beta-globin gene from a fetus diagnosed for beta 0 thalassemia. The sequence of the beta 0 gene differs from that of a normal beta-globin gene at positions 1 and 74 of the second intervening sequence (IVS2). The position 1 change alters the GT dinucleotide conserved at 5' splice sites, while the position 74 change is a common sequence polymorphism. When the cloned beta 0 gene is introduced into HeLa cells by use of an SV40-derived plasmid vector, two abnormally spliced cytoplasmic beta-globin RNAs are detected. The predominant RNA differs from normal beta-globin mRNA by the insertion of the first 47 nucleotides of IVS2 between exons 2 and 3. The less abundant RNA comprises the normal first exon spliced directly to the third. Analysis of nuclear RNA suggests that the beta 0 transcript is inefficiently spliced and that the removal of the two intervening sequences is coupled.
D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D005796:Genes; D005914:Globins / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D012323:RNA Processing, Post-Transcriptional; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics; D013789:Thalassemia / Q000235:genetics*; D014158:Transcription, Genetic
D012333:RNA, Messenger; D005914:Globins