ABSTRACT
BACKGROUND: Hypertrophic cardiomyopathy is a genetic autosomal dominant disease characterized by left ventricular hypertrophy. The molecular diagnosis is important but still expensive. This work aimed to find clinical predictors of a positive genetic test in a Brazilian tertiary centre cohort of index cases with HCM. METHODS: In the study were included patients with HCM clinical diagnosis. For genotype x phenotype comparison we have evaluated echocardiographic, electrocardiographic, and nuclear magnetic resonance measures. All patients answered a questionnaire about familial history of HCM and/or sudden death. ß-myosin heavy chain, myosin binding protein C, and troponin T genes were sequenced for genetic diagnosis. RESULTS: The variables related to a higher probability of a positive genetic test were familial history of HCM, higher mean heart frequency, presence of NSVT and lower age. Probabilities of having a positive molecular genetic test were calculated from the final multivariate logistic regression model and were used to identify those with a higher probability of a positive molecular diagnosis. CONCLUSIONS: We developed an easy and fast screening method that takes into account only clinical data that can help to select the patients with a high probability of positive genetic results from molecular sequencing of Brazilian HCM patients.
Subject(s)
Cardiomyopathy, Hypertrophic, Familial/genetics , DNA Mutational Analysis , Genetic Testing/methods , Mutation , Adolescent , Adult , Age Factors , Aged , Aged, 80 and over , Brazil , Cardiomyopathy, Hypertrophic, Familial/diagnosis , Cardiomyopathy, Hypertrophic, Familial/physiopathology , Female , Genetic Predisposition to Disease , Heart Rate , Humans , Logistic Models , Male , Middle Aged , Multivariate Analysis , Pedigree , Phenotype , Predictive Value of Tests , Risk Factors , Surveys and Questionnaires , Tachycardia, Ventricular/genetics , Tachycardia, Ventricular/physiopathology , Tertiary Care Centers , Young AdultABSTRACT
BACKGROUND: Hypertrophic cardiomyopathy (HC) is the most prevalent genetic cardiac disease caused by a mutation in sarcomeres, Z-disks, or calcium-handling genes and is characterized by unexplained left ventricular hypertrophy. The aim of this study was to determine the genetic profile of Brazilian patients with HC and correlate the genotype with the phenotype. METHODS: We included 268 index patients from São Paulo city and 3 other cities in Brazil and extracted their DNA from whole blood. We amplified the coding sequencing of MYH7, MYBPC3, and TNNT2 genes and sequenced them with an automatic sequencer. RESULTS: We identified causal mutations in 131 patients (48.8%). Seventy-eight (59.5%) were in the MYH7 gene, 50 (38.2%) in the MYBPC3 gene, and 3 (2.3%) in the TNNT2 gene. We identified 69 mutations, 24 not previously described. Patients with an identified mutation were younger at diagnosis and at current age, had a higher mean heart rate and higher nonsustained ventricular tachycardia frequency compared with those without a mutation. Patients with MYH7 gene mutations had a larger left atrium and higher frequency of atrial fibrillation than did patients with MYBPC3 gene mutations. CONCLUSION: The presence of a mutation in one of the genes suggests a worse prognosis. Mutations in the MYH7 gene, rather than in the MYBPC3 gene, were also related to a worse prognosis. This is the first work characterizing HC molecular epidemiology in the Brazilian population for the 3 most important genes.
Subject(s)
Cardiac Myosins/genetics , Cardiomyopathy, Hypertrophic/genetics , Carrier Proteins/genetics , DNA/genetics , Genetic Testing/methods , Mutation , Myosin Heavy Chains/genetics , Troponin T/genetics , Adolescent , Adult , Aged , Aged, 80 and over , Brazil/epidemiology , Cardiac Myosins/metabolism , Cardiomyopathy, Hypertrophic/diagnosis , Cardiomyopathy, Hypertrophic/epidemiology , Cardiomyopathy, Hypertrophic/metabolism , Carrier Proteins/metabolism , Female , Genotype , Humans , Male , Middle Aged , Myosin Heavy Chains/metabolism , Myosins , Phenotype , Polymerase Chain Reaction , Prevalence , Troponin T/metabolism , Young AdultABSTRACT
BACKGROUND: In hypertrophic cardiomyopathy (HCM), interstitial myocardial fibrosis is an important histological modification that has been associated with sudden death and evolution toward myocardial dilation. OBJECTIVE: To prospectively evaluate the prognostic value of the collagen volume fraction in HCM. METHODS: An endomyocardial biopsy of the right ventricle was successfully performed in 21 symptomatic patients with HCM. The myocardial collagen volume fraction (CVF) was determined by histology. The CVF was also determined in fragments of nine normal hearts from subjects deceased from non-cardiac causes. The patients were divided into above-median CVF and below-median CVF groups, and their clinical and echocardiographic characteristics and survival curves were compared. RESULTS: Among the patients, the CVF ranged from 1.86% to 29.9%, median 6.19%; in normal hearts, from 0.13% to 1.46%, median 0.61% (p <0.0001 between HCM and control). There were no significant correlations between CVF and baseline echocardiographic measures. Patients with CVF < or =6.19% and CVF> 6.19% were compared and no baseline differences were observed. However, after an average follow-up period of 110 months, four deaths occurred (two sudden, two due to heart failure) in the group with increased CVF, whereas the patients of the group with lower CVF were all alive at the end of the period (p = 0.02). CONCLUSION: For the first time, myocardial fibrosis was prospectively associated with a worse prognosis in patients with HCM. Efforts should be directed to the quantification of myocardial fibrosis in HCM, on the premise that its association with the prognosis can aid in the stratification of risk for defibrillator implantation, and in the prescription of drugs that potentially promote myocardial repair.
