putative exonic splicing enhancer in exon 7 of the PDHA1 gene affects splicing of adjacent exons

• Published in: Human mutation Vol. 29; no. 3; p. 451
• Main Authors: Ridout, C.K, Keighley, P, Krywawych, S, Brown, R.M, Brown, G.K
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01-03-2008
• Subjects: Animals; Base Sequence; Cells, Cultured; Cercopithecus aethiops; Codon, Nonsense; COS Cells; DNA - genetics; Enhancer Elements, Genetic; exonic splicing enhancer; Exons; Genetic Vectors; Humans; Mutagenesis, Site-Directed; nonsense mutation; PDHA1; pyruvate dehydrogenase; Pyruvate Dehydrogenase (Lipoamide) - genetics; Pyruvate Dehydrogenase Complex Deficiency Disease - enzymology; Pyruvate Dehydrogenase Complex Deficiency Disease - genetics; RNA Splicing - genetics; RNA, Messenger - genetics; RNA, Messenger - metabolism; splicing; Transfection
• ISSN: 1059-7794; 1098-1004
• DOI: 10.1002/humu.9525

A nonsense mutation (c.729C>A, Y243X) in exon 7 of the PDHA1 gene in a patient with pyruvate dehydrogenase deficiency results in aberrant splicing of the primary transcript with production of stable mRNAs which lack either both exons 6 and 7 or exon 7 alone. Transfection and expression of genomic constructs covering exons 5 to 8 of the mutant PDHA1 gene reproduced this aberrant splicing in vitro. The same pattern of abnormal splicing was found when a silent mutation was introduced at the same position. Both the nonsense and silent mutations alter a strong consensus site for the binding of SRp40, suggesting that they may interfere with an exonic splicing enhancer in exon 7 of the gene. However, this appears to affect splicing of not only exon 7, but also the adjacent upstream exon. The splice acceptor site of intron 5 has weak homology to the consensus sequence and this may contribute to the combined splicing defect.