title: Clinical and genetic diagnosis of familial hypertrophic cardiomyopathy: Results in pediatric cardiology.
abstract: BACKGROUND
  Hypertrophic cardiomyopathy (HCM) is most often of autosomal dominant inheritance with incomplete penetrance and variable expression. The main purpose of family screening is to identify relatives with unrecognized HCM and to monitor those at risk for disease, in order to minimize complications and to assess risk of sudden cardiac death. The ESC and ACCF/AHA guidelines on the diagnosis and management of HCM recommend the screening of child relatives from the age of 10-12 years.
  
  
  OBJECTIVE
  We studied the outcome of clinical screening and genetic testing of child probands and relatives (<18 years of age) from families with HCM and assessed the age-related penetrance of HCM during the follow-up of these young relatives.
  
  
  RESULTS
  Twenty patients from ten families were included between 2004 and 2013, consisting of three probands and 17 first-degree relatives (80% male; median age 10 years). Fourteen child relatives were mutation carriers (70%; median age eight years). Seven (50%) of the 14 mutation carriers were diagnosed with HCM at initial assessment. At-risk child relatives were defined as those with a positive mutation but a negative phenotype at enrollment. After 3.5±0.8 years of follow-up, two of the phenotype-negative mutation carriers developed HCM at 10 and 15 years of age (28% penetrance rate).
  
  
  CONCLUSIONS
  The penetrance of HCM in phenotype-negative child relatives was 28% after 3.5 years of follow-up. This underlines the need for long-term monitoring of mutation carriers irrespective of the presence of a positive phenotype.
authors.affiliation: Serviço de Cardiologia Pediátrica, Hospital de Santa Marta, Centro Hospitalar de Lisboa Central, Lisboa, Portugal. Electronic address: barbaracardoso.ba@gmail.com.
authors.forename: Bárbara
authors.initials: B
authors.lastname: Cardoso
authors.affiliation: Serviço de Cardiologia Pediátrica, Hospital de Santa Marta, Centro Hospitalar de Lisboa Central, Lisboa, Portugal.
authors.forename: Inês
authors.initials: I
authors.lastname: Gomes
authors.affiliation: Serviço de Cardiologia Pediátrica, Hospital de Santa Marta, Centro Hospitalar de Lisboa Central, Lisboa, Portugal.
authors.forename: Petra
authors.initials: P
authors.lastname: Loureiro
authors.affiliation: Serviço de Cardiologia Pediátrica, Hospital de Santa Marta, Centro Hospitalar de Lisboa Central, Lisboa, Portugal.
authors.forename: Conceição
authors.initials: C
authors.lastname: Trigo
authors.affiliation: Serviço de Cardiologia Pediátrica, Hospital de Santa Marta, Centro Hospitalar de Lisboa Central, Lisboa, Portugal.
authors.forename: Fátima
authors.initials: F
authors.lastname: Ferreira Pinto
mesh_terms: D000293:Adolescent; D024741:Cardiomyopathy, Hypertrophic, Familial / Q000175:diagnosis* / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005820:Genetic Testing; D006801:Humans; D007223:Infant; D008297:Male; D010375:Pedigree
keywords: Children; Crianças; Diagnóstico genético; Familial hypertrophic cardiomyopathy; Genetic testing; Miocardiopatia hipertrófica familiar; Penetrance; Penetrância