title: A Long Term Follow-up Study of Carriers of Hypertrophic Cardiomyopathy Mutations.
abstract: BACKGROUND
  Adults who test positive for a mutation associated with the development of hypertrophic cardiomyopathy (HCM) but who have not manifested left ventricular hypertrophy (LVH) at the time of that diagnosis are now commonly identified in the era of genetic testing. There are little published data, however, on the long-term outlook for these phenotypically normal gene carriers.
  
  
  METHODS
  Fifteen genotype positive/LVH negative patients with HCM were identified, seven of which were children when first diagnosed as gene carriers. Fourteen were followed up with clinical examinations, electrocardiography and echocardiography to determine if their clinical status had changed over time. Measurements included electrocardiographic changes, changes in wall thickness, diastolic function and global longitudinal stain.
  
  
  RESULTS
  Ten participants were followed up for a total of 18 years, two for a total of 17 years, one for 11 years and one for 8 years. In addition, magnetic resonance imaging (MRI) studies were performed on 11 participants. Eleven participants carried a mutation for the MYBPC3 gene and three carried a mutation for the MYH7 gene. One patient, an adult at the time of initial investigation, developed phenotypic features of HCM on echocardiography and MRI, one an increase in wall thickness diagnostic for HCM only on MRI and another to be borderline for HCM on MRI.
  
  
  CONCLUSIONS
  Hypertrophic cardiomyopathy can develop in adult life in carriers who may be negative for LVH at the time of gene diagnosis and warrants periodic supervision of carriers throughout their lives.
authors.affiliation: Cardiology, Launceston General Hospital, Launceston, Tas, Australia. Electronic address: dmctaggart2@bigpond.com.
authors.forename: Don R
authors.initials: DR
authors.lastname: McTaggart
authors.affiliation: School of Medicine, University of Tasmania, Hobart, TAS, Australia.
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: Ogden
authors.affiliation: Central Adelaide Local Health Network, Adelaide, SA, Australia.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Marathe
mesh_terms: D000328:Adult; D024722:Cardiac Myosins / Q000235:genetics*; D002312:Cardiomyopathy, Hypertrophic / Q000000981:diagnostic imaging / Q000235:genetics / Q000503:physiopathology; D002352:Carrier Proteins / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000000981:diagnostic imaging / Q000235:genetics / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D018995:Myosin Heavy Chains / Q000235:genetics*; D000099163:Myosin Binding Protein C
chemical_list: D024722:Cardiac Myosins; D002352:Carrier Proteins; D018995:Myosin Heavy Chains; D000099163:Myosin Binding Protein C; C501641:MYH7 protein, human
keywords: Carriers; Clinical genetics; Hypertrophic cardiomyopathy; Long-term follow-up