Micro-exons of the cardiac myosin binding protein C gene: flanking introns contain a disproportionately large number of hypertrophic cardiomyopathy mutations.
Hypertrophic cardiomyopathy is primarily caused by mutations in genes encoding cardiac sarcomere proteins. Large screening studies identify mutations in 35-65% of the diagnosed patients and 15-30% of these are discovered within the MYBPC3 gene encoding the cardiac myosin binding protein C. The aim of this study is to determine whether intronic variation flanking the three micro-exons in MYBPC3 is disease-causing. Two hundred and fifty unrelated patients with hypertrophic cardiomyopathy were genotyped in MYBPC3, using automated single-strand conformation polymorphism, and sequenced for confirmation. Mutations located in the flanking introns of the MYBPC3 micro-exons were examined using in silico methods. Ectopic expression of mRNA in blood leukocytes in the respective patients was examined using reverse transcription-PCR. A total of seven mutations were discovered in the introns flanking the two micro-exons 10 and 14, but none were found in introns flanking exon 11. Functional studies together with co-segregation analysis indicate that four mutations are associated with HCM, in the respective patients. All four mutations result in premature termination codons, which suggests that haploinsufficiency is a pathogenic mechanism of this type of mutation. It is demonstrated that the use of in silico methods together with RNA studies on peripheral blood leukocytes is a useful tool to evaluate the potential effects of mutations on pre-mRNA splicing.
Frank-Hansen
Rune
R
Department of Clinical Biochemistry, Statens Serum Institut, Copenhagen, Denmark.
Page
Stephen P
SP
Syrris
Petros
P
McKenna
William J
WJ
Christiansen
Michael
M
Andersen
Paal Skytt
PS
D000328:Adult; D000368:Aged; D002312:Cardiomyopathy, Hypertrophic / Q000175:diagnosis / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D018389:Codon, Nonsense / Q000235:genetics; D018388:Codon, Terminator / Q000235:genetics; D005091:Exons / Q000235:genetics*; D005260:Female; D006238:Haploidy; D006801:Humans; D007438:Introns / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism; D010375:Pedigree; D017354:Point Mutation / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D022821:RNA Splice Sites / Q000235:genetics; D000099163:Myosin Binding Protein C
D002352:Carrier Proteins; D018389:Codon, Nonsense; D018388:Codon, Terminator; D022821:RNA Splice Sites; D000099163:Myosin Binding Protein C