Clinical and ECG variables to predict the outcome of genetic testing in hypertrophic cardiomyopathy

Knowledge on the influence of specific genotypes on the phenotypic expression of hypertrophic cardiomyopathy (HCM) is emerging. The objective of this study was to evaluate the genotype-phenotype relation in HCM patients and to construct a score to predict the genetic yield based to improve counseling. Unrelated HCM patients who underwent genetic testing were included in the analysis. Multivariate logistic regression was performed to identify variables that predict a positive genetic test. A weighted score was constructed based on the odds ratios. In total, 378 HCM patients were included of whom 141 carried a mutation (global yield 37%), 181 were mutation negative and 56 only carried a variant of unknown significance. We identified age at diagnosis <45 years, familial HCM, familial sudden death, arrhythmic syncope, maximal wall thickness ≥20 mm, asymmetrical hypertrophy and the absence of negative T waves in the lateral ECG leads as significant predictors of a positive genetic test. When we included these values in a risk score we found very high correlation between the score and the observed genetic yield (Pearson r = 0.98). MYBPC3 mutation carriers more frequently suffered sudden cardiac death compared to troponin complex mutations carriers (p = 0.01) and a similar trend was observed compared to MYH7 mutation carriers (p = 0.08) and mutation negative patients (p = 0.11). To conclude, a simple score system based on clinical variables can predict the genetic yield in HCM index patients, aiding in counseling HCM patients. MYBPC3 mutation carriers had a worse outcome regarding sudden cardiac death.     

Uptake of genetic counselling and predictive DNA testing in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is a common autosomal dominant disease, associated with heart failure and arrhythmias predisposing to sudden cardiac death. After the detection of the causal mutation in the proband predictive DNA testing of relatives is possible (cascade screening). Prevention of sudden cardiac death in patients with a high risk by means of an implantable cardioverter defibrillator is effective. In 97 hypertrophic cardiomyopathy families with a sarcomere gene mutation we retrospectively determined uptake of genetic counselling and predictive DNA testing in relatives within 1 year after the detection of the causal mutation in the proband. Uptake of genetic counselling was 39% and did not differ significantly by proband's or relative's gender, nor by young age of the relative (< 18 years) or a family history positive for sudden cardiac death. In second-degree relatives, eligible for predictive DNA testing when the first-degree relative had died, uptake was 27.5% (P = 0.047). Uptake of predictive genetic testing was 39%; conditional uptake of predictive genetic testing was 99%. Uptake of genetic counselling in hypertrophic cardiomyopathy is comparable to uptake in oncogenetics. Conditional uptake of predictive DNA testing, however, is much higher. Because sudden cardiac death can be prevented uptake of genetic counselling in hypertrophic cardiomyopathy should be as high as possible. To achieve this research into the determinants of uptake is needed.     

Genetic testing and genetic counselling in hypertrophic cardiomyopathy: the French experience

Methods and results: The main questions asked by patients and relatives concern presymptomatic diagnosis and prenatal counselling/diagnosis, while clinicians sometimes discuss diagnostic and prognostic testing. To take into account the complex medical and psychological implications of this new approach, we developed a specific, multidisciplinary, and multiple step procedure, including a cardiologist, a geneticist, and a psychologist. Seventy subjects were examined, including (1) 29 adults for presymptomatic diagnosis (of whom 10 left the procedure after the first visit and 19 continued, among whom six had a mutation and two experienced negative psychological impact, observed during follow up), (2) nine couples of parents for presymptomatic diagnosis in their children (the procedure was stopped after the first visit in eight and continued in one), (3) 22 couples for prenatal counselling (no prenatal genetic testing was asked for after the first visit), and (4) 10 subjects for diagnostic testing. We decided to perform no prognostic testing.

Conclusion: Our preliminary experience confirms the complexity of the situation and suggests the necessity for a specific procedure to ensure good practice in genetic testing of HCM.

     

Post-mortem genetic testing in a family with long-QT syndrome and hypertrophic cardiomyopathy

Pediatric sudden unexplained deaths are rare and tragic events that should be evaluated with all the tools available to the medical community. The current state of genetic testing is an excellent resource that improves our ability to diagnose cardiovascular disorders that can lead to sudden cardiac arrest. Post-mortem genetic testing is not typically a covered benefit of health insurance and may not be offered to families in the setting of a negative autopsy. This unusual case includes two separate cardiovascular disorders that highlight the use of genetic testing and its role in diagnosis, screening, and risk stratification. The insurance company's decision to cover post-mortem testing demonstrated both compassion as well as an understanding of the long-term cost effectiveness.     

Constructing "best interests": genetic testing of children in families with hypertrophic cardiomyopathy

Professional guidelines on genetic testing of children have recently shifted their focus from protecting the child's autonomous choice to professionals, together with parents, striving to work in the child's “best interest.” This notion of “best interest” allows room for therapeutical as well as psychological and social considerations, and gives rise to the question how parents and professionals weigh up the child's best interest in practice. In this qualitative study, we followed six extended families involved in genetic testing for hypertrophic cardiomyopathy in the Netherlands for 3½ years. In total 57 members of these families were interviewed in depth; many of them more than once. Our empirical analysis shows that the best interest of a child is constructed via long‐term processes in the broader context of family and kin. In this context, “best interests” are considered and reconsidered. We conclude that a child's best interest should not be framed as the result of an instantaneous agreement between parents and professionals. In dealing with genetic testing of children, parents as well as professionals reflect on and learn from the processes of generating new meanings of “best interest.” To enable professionals to deal with the variety in family life, these learning processes should be documented closely. © 2011 Wiley‐Liss, Inc.     

Compound and double mutations in patients with hypertrophic cardiomyopathy: implications for genetic testing and counselling

Objective: To report the frequency of single and multiple gene mutations in an Australian cohort of patients with hypertrophic cardiomyopathy (HCM). Methods: Genetic screening of seven HCM genes (ß-MHC, MyBP-C, cTnT, cTnI, ACTC, MYL2, and MYL3) was undertaken in 80 unrelated probands. Screening was by denaturing high performance liquid chromatography and direct DNA sequencing. Clinical data were collected on all patients and on genotyped family members. Results: 26 mutations were identified in 23 families (29%). Nineteen probands (24%) had single mutations (11 ß-MHC, 4 MyBP-C, 3 cTnI, 1 cTnT). Multiple gene mutations were identified in four probands (5%): one had a double mutation and the others had compound mutations. Six of 14 affected individuals from multiple mutation families (43%) experienced a sudden cardiac death event, compared with 10 of 55 affected members (18%) from single mutation families (p = 0.05). There was an increase in septal wall thickness in patients with compound mutations (mean (SD): 30.7 (3.1) v 24.4 (7.4) mm; p<0.05). Conclusions: Multiple gene mutations occurring in HCM families may result in a more severe clinical phenotype because of a "double dose" effect. This highlights the importance of screening the entire panel of HCM genes even after a single mutation has been identified.     

DNA testing in familial hypertrophic cardiomyopathy: clinical and laboratory implications

Counselling and clinical assessment in familial hypertrophic cardiomyopathy (FHC) is difficult, particularly in the young, since echocardiographic and ECG changes may not be diagnostic and clinical severity can vary. From 1990, when the β-cardiac myosin heavy chain gene was implicated in the aetiology of FHC, considerable information about the molecular genetics of this disorder has emerged. However, an important question facing health professionals is the practical significance of DNA testing in FHC. The present study describes a DNA-based approach to screening for five commonly reported mutations involving the-cardiac myosin heavy chain gene. Approximately 11% of randomly selected families had an abnormality detected.     

Results of clinical genetic testing of 2,912 probands with hypertrophic cardiomyopathy: expanded panels offer limited additional sensitivity

PurposeHypertrophic cardiomyopathy (HCM) is caused primarily by pathogenic variants in genes encoding sarcomere proteins. We report genetic testing results for HCM in 2,912 unrelated individuals with nonsyndromic presentations from a broad referral population over 10 years.MethodsGenetic testing was performed by Sanger sequencing for 10 genes from 2004 to 2007, by HCM CardioChip for 11 genes from 2007 to 2011 and by next-generation sequencing for 18, 46, or 51 genes from 2011 onward.ResultsThe detection rate is ~32% among unselected probands, with inconclusive results in an additional 15%. Detection rates were not significantly different between adult and pediatric probands but were higher in females compared with males. An expanded gene panel encompassing more than 50 genes identified only a very small number of additional pathogenic variants beyond those identifiable in our original panels, which examined 11 genes. Familial genetic testing in at-risk family members eliminated the need for longitudinal cardiac evaluations in 691 individuals. Based on the projected costs derived from Medicare fee schedules for the recommended clinical evaluations of HCM family members by the American College of Cardiology Foundation/American Heart Association, our data indicate that genetic testing resulted in a minimum cost savings of about $0.7 million.ConclusionClinical HCM genetic testing provides a definitive molecular diagnosis for many patients and provides cost savings to families. Expanded gene panels have not substantively increased the clinical sensitivity of HCM testing, suggesting major additional causes of HCM still remain to be identified.Genet Med17 11, 880–888.     

Psychosocial impact of specialized cardiac genetic clinics for hypertrophic cardiomyopathy

PurposeThe diagnosis of hypertrophic cardiomyopathy, an autosomal dominant chronic heart disease, can have significant implications, including increased risk of sudden death, exercise limitations, and risk of transmission to offspring. This study sought to describe the psychosocial factors associated with attending a specialty cardiac genetic clinic, and to determine whether these may be predictors of comorbid anxiety and depression in this population.MethodsQuestionnaires were sent to 184 individuals attending the Royal Prince Alfred Hospital Hypertrophic Cardiomyopathy Clinic. Questionnaires were anonymous and comprised demographics, the Hospital Anxiety and Depression Scale, Patient Experience Scales, and Patient Satisfaction Scales.ResultsCompleted questionnaires were returned by 109 participants (59.2% response rate), of which 76.9% had a diagnosis of hypertrophic cardiomyopathy, while 23.1% were at-risk relatives attending for clinical screening. Patient satisfaction scores were generally high to very high across all groups, though only 24% of HCM patients showed good adjustment to hypertrophic cardiomyopathy and 10% had low worry about hypertrophic cardiomyopathy scores. Within the disease group, logistic regression analysis adjusting for age, gender, and education revealed adjustment to hypertrophic cardiomyopathy and worry about hypertrophic cardiomyopathy scores to be significantly associated with anxiety, while adjustment scores and location of patient follow-up (i.e., Hypertrophic Cardiomyopathy clinic or another cardiologist) to be significantly associated with depression scores.ConclusionHCM patients who attend specialized cardiac genetic clinics are better adjusted and worry less, than those who do not attend. An integrated approach, including a genetic counselor, is important in the management of HCM families.     

Clinical and morphological features of hypertrophic cardiomyopathy in Korean patients

Thirty three cases of hypertrophic cardiomyopathy (HCMP) were reviewed to estimate the relative frequencies of the subtypes of HCMP and to clarify whether there is any racial difference in clinical and morphological features of HCMP. The diagnosis was made by echocardiography, cardiac catheterization and left ventriculography. Twenty four patients underwent coronary angiogram. Numbers of cases by the types of HCMP were 20 (61%) with asymmetrical septal hypertrophy (ASH), 11 (33%) with apical hypertrophy (APH) and 2 (6%) with midventricular hypertrophy (MVH). Mean ages of the patients with APH, ASH and MVH were 54, 46 and 31 years respectively, and the differences were statistically significant (p less than 0.05). The giant negative T wave on electrocardiogram was seen in 4 patients (20%) of ASH and 5 patients (45%) of APH. On echocardiogram mean ratio of interventricular septal to left ventricular posterior wall thickness was 1.9 in ASH, 1.2 in APH and 1.6 in MVH, and the differences were statistically significant (p less than 0.05). All patients with APH showed "spade of ace" deformity in left ventriculography. Coronary angiograms were normal in all patients who had the procedure. Our study showed high frequency of APH of which characteristics were similar to those of the Japanese type APH.     

Lack of reliable clinical predictors to identify obstructive sleep apnea in patients with hypertrophic cardiomyopathy

OBJECTIVE:

Obstructive sleep apnea is common among patients with hypertrophic cardiomyopathy and may contribute to poor cardiovascular outcomes. However, obstructive sleep apnea is largely unrecognized in this population. We sought to identify the clinical predictors of obstructive sleep apnea among patients with hypertrophic cardiomyopathy.

METHODS:

Consecutive patients with hypertrophic cardiomyopathy were recruited from a tertiary University Hospital and were evaluated using validated sleep questionnaires (Berlin and Epworth) and overnight portable monitoring. Ninety patients (males, 51%; age, 46±15 years; body mass index, 26.6±4.9 kg/m²) were included, and obstructive sleep apnea (respiratory disturbance index ≥15 events/h) was present in 37 patients (41%).

RESULTS:

Compared with the patients without obstructive sleep apnea, patients with obstructive sleep apnea were older and had higher body mass index, larger waist circumference, larger neck circumference, and higher prevalence of atrial fibrillation. Excessive daytime sleepiness (Epworth scale) was low and similar in the patients with and without obstructive sleep apnea, respectively. The only predictors of obstructive sleep apnea (using a logistic regression analysis) were age ≥45 years (odds ratio [OR], 4.46; 95% confidence interval [CI 95%], 1.47–13.54; p = 0.008) and the presence of atrial fibrillation [OR, 5.37; CI 95%, 1.43–20.12; p = 0.013].

CONCLUSION:

Consistent clinical predictors of obstructive sleep apnea are lacking for patients with hypertrophic cardiomyopathy, which suggests that objective sleep evaluations should be considered in this population, particularly among elderly patients with atrial fibrillation.     

Determining pathogenicity of genetic variants in hypertrophic cardiomyopathy: importance of periodic reassessment

PurposeMajor advances have been made in our understanding and clinical application of genetic testing in hypertrophic cardiomyopathy. Determining pathogenicity of a single-nucleotide variant remains a major clinical challenge. This study sought to reassess single-nucleotide variant classification in hypertrophic cardiomyopathy probands.MethodsConsecutive probands with hypertrophic cardiomyopathy with a reported pathogenic mutation or variation of uncertain significance were included. Family and medical history were obtained. Each single-nucleotide variant was reassessed by a panel of four reviewers for pathogenicity based on established criteria together with updated cosegregation data and current population-based allele frequencies.ResultsFrom 2000 to 2012, a total of 136 unrelated hypertrophic cardiomyopathy probands had genetic testing, of which 63 (46%) carried at least one pathogenic mutation. MYBPC3 (n = 34; 47%) and MYH7 (n = 23; 32%) gene variants together accounted for 79%. Five variants in six probands (10%) were reclassified: two variation of uncertain significance were upgraded to pathogenic, one variation of uncertain significance and one pathogenic variant were downgraded to benign, and one pathogenic variant (found in two families) was downgraded to variation of uncertain significance. None of the reclassifications had any adverse clinical consequences.ConclusionGiven the rapid growth of genetic information available in both disease and normal populations, periodic reassessment of single-nucleotide variant data is essential in hypertrophic cardiomyopathy.Genet Med 2014:16(4):286–293.     

Familial hypertrophic cardiomyopathy

Two genetically associated observations of the familial cardiomyopathy in a 34-year-old father and 2-day-old son are described. Verification of the lesions is performed by means of macro-and microscopic analysis including the post-mortem contrast cardioventriculography and histotopographic investigation. Specific changes in the interventricular septum and left ventricle are found in both cases as well as asymmetric hypertrophy and elimination of the cavity of the left ventricle in both father and son.