Molecular and functional characterization of novel hypertrophic cardiomyopathy susceptibility mutations in TNNC1-encoded troponin C.
Hypertrophic Cardiomyopathy (HCM) is a common primary cardiac disorder defined by a hypertrophied left ventricle, is one of the main causes of sudden death in young athletes, and has been associated with mutations in most sarcomeric proteins (tropomyosin, troponin T and I, and actin, etc.). Many of these mutations appear to affect the functional properties of cardiac troponin C (cTnC), i.e., by increasing the Ca(2+)-sensitivity of contraction, a hallmark of HCM, yet surprisingly, prior to this report, cTnC had not been classified as a HCM-susceptibility gene. In this study, we show that mutations occurring in the human cTnC (HcTnC) gene (TNNC1) have the same prevalence (~0.4%) as well established HCM-susceptibility genes that encode other sarcomeric proteins. Comprehensive open reading frame/splice site mutation analysis of TNNC1 performed on 1025 unrelated HCM patients enrolled over the last 10 years revealed novel missense mutations in TNNC1: A8V, C84Y, E134D, and D145E. Functional studies with these recombinant HcTnC HCM mutations showed increased Ca(2+) sensitivity of force development (A8V, C84Y and D145E) and force recovery (A8V and D145E). These results are consistent with the HCM functional phenotypes seen with other sarcomeric-HCM mutations (E134D showed no changes in these parameters). This is the largest cohort analysis of TNNC1 in HCM that details the discovery of at least three novel HCM-associated mutations and more strongly links TNNC1 to HCM along with functional evidence that supports a central role for its involvement in the disease. This study may help to further define TNNC1 as an HCM-susceptibility gene, a classification that has already been established for the other members of the troponin complex.
Mayo Medical School, Mayo Clinic, Rochester, MN, USA.
Andrew P
AP
Landstrom
Michelle S
MS
Parvatiyar
Jose R
JR
Pinto
Michelle L
ML
Marquardt
J Martijn
JM
Bos
David J
DJ
Tester
Steve R
SR
Ommen
James D
JD
Potter
Michael J
MJ
Ackerman
D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D002312:Cardiomyopathy, Hypertrophic / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D015331:Cohort Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D051379:Mice; D008875:Middle Aged; D008969:Molecular Sequence Data; D020125:Mutation, Missense / Q000235:genetics*; D051381:Rats; D013552:Swine; D019209:Troponin C / Q000145:classification / Q000235:genetics* / Q000502:physiology
D019209:Troponin C