A novel single-base substitution (c.1124A>G) that activates a 5-base upstream cryptic splice donor site within exon 11 in the human mitochondrial acetoacetyl-CoA thiolase gene.
Most mutations related to aberrant splicing occur in conserved splice acceptor and donor sites. Some exonic mutations also affect splicing. We identified and characterized a point mutation (c.1124A>G) in an Australian patient (GK43) with mitochondrial acetoacetyl-CoA thiolase (T2) deficiency. GK43 is a homozygote of c.1124A>G, which activates a cryptic splice donor site 5 bases upstream from c.1124A>G within exon 11, causing aberrant splicing in most transcripts. The aberrant splicing results in c.1120-1163 (44-base) deletion, causing a frameshift in T2 mRNA. A mini-gene splicing experiment confirmed that the c.1124A>G substitution was responsible for this aberrant splicing. This cryptic splice site has a Shapiro and Senapathy score (70.0) in a normal sequence but if mutated, the score (84.3) becomes higher than the one in the authentic splice donor site of intron 11 (81.4). This is an example in which a point mutation activates a cryptic splice donor site motif that is used preferentially over a downstream authentic splice site.
Fukao
Toshiyuki
T
Department of Pediatrics, Graduate School of Medicine, Gifu University, 1-1 Yanagido, Gifu 501-1194, Japan; Division of Medical Information Sciences, United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1194, Japan.
Boneh
Avihu
A
Metabolic Service, Murdoch Childrens Research Institute, Royal Children's Hospital, Department of Paediatrics, University of Melbourne, Australia.
Aoki
Yusuke
Y
Department of Pediatrics, Graduate School of Medicine, Gifu University, 1-1 Yanagido, Gifu 501-1194, Japan.
Kondo
Naomi
N
Department of Pediatrics, Graduate School of Medicine, Gifu University, 1-1 Yanagido, Gifu 501-1194, Japan.
D000101:Acetyl-CoA C-Acetyltransferase / Q000235:genetics* / Q000378:metabolism; D017398:Alternative Splicing; D001483:Base Sequence; D002478:Cells, Cultured; D002675:Child, Preschool; D018076:DNA, Complementary / Q000235:genetics; D005091:Exons; D005260:Female; D005347:Fibroblasts / Q000201:enzymology / Q000502:physiology; D015870:Gene Expression; D006801:Humans; D008661:Metabolism, Inborn Errors / Q000201:enzymology / Q000235:genetics*; D008928:Mitochondria / Q000201:enzymology* / Q000235:genetics; D017354:Point Mutation; D022821:RNA Splice Sites
D018076:DNA, Complementary; D022821:RNA Splice Sites; C506639:ACAT1 protein, human; D000101:Acetyl-CoA C-Acetyltransferase