title: Genetic screening and double mutation in Japanese patients with hypertrophic cardiomyopathy.
abstract: BACKGROUND
  Hypertrophic cardiomyopathy (HCM) is a primary myocardial disorder with an autosomal-dominant pattern of inheritance mainly caused by single heterozygous mutations in sarcomere genes. Although multiple gene mutations have recently been reported in Western countries, clinical implications of multiple mutations in Japanese subjects are not clear.
  
  
  RESULTS
  A comprehensive genetic analysis of 5 sarcomere genes (cardiac β-myosin heavy chain gene [MYH7], cardiac myosin-binding protein C gene [MYBPC3], cardiac troponin T gene [TNNT2], α-tropomyosin gene [TPM1] and cardiac troponin I gene [TNNI3]) was performed in 93 unrelated patients and 14 mutations were identified in 28 patients. Twenty-six patients had single heterozygosity (20 in MYBPC3, 4 in MYH7, 1 in TNNT2, 1 in TNNI3), whereas 2 proband patients with familial HCM had double heterozygosity: 1 with P106fs in MYBPC3 and R869C in MYH7 and 1 with R945fs in MYBPC3 and E1049D in MYH7. From the results of the family survey and the previous literature on HCM mutations, P106fs, R945fs and R869C seemed to be pathological mutations and E1049D might be a rare polymorphism. The proband patient with P106fs and R869C double mutation was diagnosed as having HCM at an earlier age (28 years of age) than her relatives with single mutation, and had greater wall thickness with left ventricular outflow obstruction.
  
  
  CONCLUSIONS
  One double mutation was identified in a Japanese cohort of HCM patients. Further studies are needed to clarify the clinical significance of multiple mutations including phenotypic severity.
authors.affiliation: Department of Medicine and Geriatrics, Kochi Medical School, Tokyo, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Kubo
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kitaoka
authors.forename: Makoto
authors.initials: M
authors.lastname: Okawa
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Baba
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Hirota
authors.forename: Kayo
authors.initials: K
authors.lastname: Hayato
authors.forename: Naohito
authors.initials: N
authors.lastname: Yamasaki
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Matsumura
authors.forename: Haruna
authors.initials: H
authors.lastname: Otsuka
authors.forename: Takuro
authors.initials: T
authors.lastname: Arimura
authors.forename: Akinori
authors.initials: A
authors.lastname: Kimura
authors.forename: Yoshinori L
authors.initials: YL
authors.lastname: Doi
mesh_terms: D000328:Adult; D000368:Aged; D044466:Asian People; D024741:Cardiomyopathy, Hypertrophic, Familial / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D015331:Cohort Studies; D005260:Female; D005820:Genetic Testing; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D009124:Muscle Proteins / Q000235:genetics*; D009154:Mutation; D010375:Pedigree; D011110:Polymorphism, Genetic
chemical_list: D009124:Muscle Proteins