Elisa Mazzotti

Multiple mutations in desmosomal proteins encoding genes in arrhythmogenic right ventricular cardiomyopathy/dysplasia

BACKGROUND Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a progressive cardiomyopathy showing a wide clinical spectrum in terms of clinical expressions and prognoses. OBJECTIVE This study sought to estimate the occurrence of compound and double heterozygotes for mutations in desmosomal proteins encoding genes in a cohort of ARVC/D Italian index cases, and to assess the clinical phenotype of mutations carriers. METHODS Fourty-two consecutive ARVC/D index cases who fulfilled the International Task Force diagnostic criteria were screened for mutations in PKP2, DSP, DSG2, DSC2, and JUP genes by denaturing high-performance liquid chromatography (DHPLC) and direct sequencing. RESULTS Three probands (7.1%) showing a family history of sudden death carried multiple mutations. Family screening identified an additional 7 multiple-mutation carriers. Among the 7 double heterozygotes for mutations in different genes, 2 were clinically unaffected, 2 were affected, and 3 showed some clinical signs of ARVC/D even if they did not fulfill the diagnostic criteria. Two compound heterozygotes for mutations in the same gene and 1 subject carrying 3 different mutations showed a severe form of the disease with heart failure onset at a young age. Moreover, multiple-mutation carriers showed a higher prevalence of left ventricular involvement (P = .025) than single-mutation carriers. CONCLUSION Occurrence of compound and double heterozygotes in ARVC/D index cases is particularly relevant to mutation screening strategy and to genetic counseling. Even if multiple-mutation carriers show a wide variability in clinical expression, the extent of the disease is higher compared to that in single-mutation carriers.

Compound and digenic heterozygosity predicts lifetime arrhythmic outcome and sudden cardiac death in desmosomal gene-related arrhythmogenic right ventricular cardiomyopathy.

Background—Mutations in genes encoding for desmosomal proteins are the most common cause of arrhythmogenic right ventricular cardiomyopathy (ARVC). We assessed the value of genotype for prediction of lifetime major arrhythmic events and sudden cardiac death (SCD) in desmosomal gene–related ARVC. Methods and Results—The overall study population included 134 desmosomal gene mutation carriers (68 men; median age 36 years [22–52]) from 44 consecutive ARVC families undergoing comprehensive genetic screening. The probability of experiencing a first major arrhythmic event or SCD during a lifetime was determined by using date of birth as start point for the time-to-event analysis, and was stratified by sex, desmosomal genes, mutation types, and genotype complexity (single versus multiple mutations). One hundred thirteen patients (84%) carried a single desmosomal gene mutation in desmoplakin (n=44; 39%), plakophilin-2 (n=38; 34%), desmoglein-2 (n=30; 26%), and desmocollin-2 (n=1; 1%), whereas 21 patients (16%) had a complex genotype with compound heterozygosity in 7 and digenic heterozygosity in 14. Over a median observation period of 39 (22–52) years, 22 patients (16%) from 20 different families had arrhythmic events, such as SCD (n=1), aborted SCD because of ventricular fibrillation (n=6), sustained ventricular tachycardia (n=14), and appropriate defibrillator intervention (n=1). Multiple desmosomal gene mutations and male sex were independent predictors of lifetime arrhythmic events with a hazard ratio of 3.71 (95% confidence interval, 1.54–8.92; P=0.003) and 2.76 (95% confidence interval, 1.19–6.41; P=0.02), respectively. Conclusions—Compound/digenic heterozygosity was identified in 16% of ARVC-causing desmosomal gene mutation carriers and was a powerful risk factor for lifetime major arrhythmic events and SCD. These results support the use of comprehensive genetic screening of desmosomal genes for arrhythmic risk stratification in ARVC.

Mutations in the area composita protein αT-catenin are associated with arrhythmogenic right ventricular cardiomyopathy

AIMS Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a major cause of juvenile sudden death and is characterized by fibro-fatty replacement of the right ventricle. Mutations in several genes encoding desmosomal proteins have been identified in ARVC. We speculated that αT-catenin, encoded by CTNNA3, might also carry mutations in ARVC patients. Alpha-T-catenin binds plakophilins and this binding contributes to the formation of the area composita, which strengthens cell-cell adhesion in contractile cardiomyocytes. METHODS AND RESULTS We used denaturing high-performance liquid chromatography and direct sequencing to screen CTNNA3 in 76 ARVC patients who did not carry any mutations in the desmosomal genes commonly mutated in ARVC. Mutations c.281T > A (p.V94D) and c.2293_2295delTTG (p.del765L) were identified in two probands. They are located in important domains of αT-catenin. Yeast two-hybrid and cell transfection studies showed that the interaction between the p.V94D mutant protein and β-catenin was affected, whereas the p.del765L mutant protein showed a much stronger dimerization potential and formed aggresomes in HEK293T cells. CONCLUSION These findings might point to a causal relationship between CTNNA3 mutations and ARVC. This first report on the involvement of an area composita gene in ARVC shows that the pathogenesis of this disease extends beyond desmosomes. Since the frequency of CTNNA3 mutations in ARVC patients is not rare, systematic screening for this gene should be considered to improve the clinical management of ARVC families.

Health related quality of life in adults with repaired tetralogy of Fallot: psychosocial and cognitive outcomes

Objective: To assess the health related quality of life of patients who were operated on during childhood for total correction of tetralogy of Fallot, focusing on the psychosocial and cognitive outcomes. Patients: 54 patients (24 men and 30 women, mean (SD) age 32 (4) years), operated on for total correction of tetralogy of Fallot at mean age of 8.2 years, underwent a cardiological examination, psychological assessment (semistructured interview, Minnesota multiphasic personality inventory), evaluation of quality of life (36 item short form health survey), and neuropsychological assessment with an extensive neuropsychological battery of tests. Results: Psychological characteristics—(1) a lower than normal academic level, (2) a job inadequate for educational level, (3) a preference for an overprotective familiar setting, and (4) a difficulty communicating own corporal image. Denial of the cardiopathy was found to be a common behaviour to normalise functioning. Very few patients had a deficit in memory, learning, or attention functions; rather, patients had a deficit in the executive functions, problem solving, and planning strategies. Conclusions: Despite a satisfactory health related quality of life, there are residual psychological and social problems in addition to impaired cognitive outcomes in the presence of a normal intelligence quotient.

Electrocardiographic Pattern in Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a cardiac disease characterized by progressive myocardial atrophy and fibrofatty replacement. Standard electrocardiograms (ECGs) and signal-averaged ECGs (SAECGs) were relatively low cost and repeatable diagnostic tools. In this study, ECGs and SAECGs of patients with ARVC were analyzed with the aim to assess the diagnostic capability of these noninvasive techniques. A total of 205 patients with ARVC were analyzed. ECGs were abnormal in 74% of patients and SAECGs were positive in 60%, with normal ECGs mostly related to mild forms of the disease. The most common electrocardiographic abnormalities were localized right QRS prolongation, poor r wave progression in the right precordial leads, incomplete right branch bundle block, prolonged S-wave upstroke in V(1) to V(3), parietal block, ST-segment elevation in V(1) to V(3), inversion of T waves beyond V(2), and epsilon wave. Low QRS voltages in the precordial leads were frequently present in all patients with ARVC compared with a group of 120 healthy subjects (p = 0.00001). T-wave inversion beyond V(3) characterized subjects with severe right ventricular dilatation, whereas in subjects with left ventricular involvement, T-wave inversion in lateral leads was more commonly detected. Overall, the extent of electrocardiographic abnormalities was related to disease extent. In conclusion, abnormalities in ECGs and SAECGs were frequent in patients with ARVC and correlated with disease extent, even if a stereotypical electrocardiographic pattern did not exist. ECGs and SAECGs remain an important tool for the diagnosis and assessment of ARVC extent. Nonetheless, a normal ECG does not exclude the presence of the disease.

Differences and similarities between arrhythmogenic right ventricular cardiomyopathy and athlete’s heart adaptations

Background Regular intensive physical activity is associated with non-pathological changes in cardiac morphology. Differential diagnosis with arrhythmogenic right ventricular cardiomyopathy (ARVC) constitutes a frequent problem, especially in athletes showing ventricular arrhythmias with left bundle branch block morphology. Aim of the study To assess the different clinical and non-invasive instrumental features of the subjects affected by ARVC and by athletes. Methods Three groups of subjects (40 ARVC patients, 40 athletes and 40 controls, mean age 27 (9) years) were examined with family and personal history, physical examination, 12-lead ECG, 24-h ECG, signal-averaged ECG and 2-D and Doppler echocardiography. Results 12-Lead ECG was abnormal in 62% of ARVC patients versus 7.5% of athletes and 2.5% of controls (p<0.0001). Ventricular arrhythmias and late potentials were present in 70% and 55% of ARVC subjects, respectively (vs 5% of athletes and 7.5% of controls, p<0.0001). Left ventricular parietal wall thickness and left ventricular end-diastolic diameters were significantly higher in athletes. Both athletes and ARVC patients presented a right ventricular (RV) enlargement compared with controls. Moreover, RV outflow tract, measured on parasternal long axis and at the level of aortic root, was significantly larger in ARVC patients (33.6 (4.7) mm vs 29.1 (3.4) mm and 35.6 (6.8) mm vs 30.1 (2.9) mm; p<0.0001), and RV fractional shortening and ejection fraction were significantly lower in ARVC patients compared with athletes (40 (7.9)% vs 44 (10)%; p=0.05 and 52.9 (8)% vs 59.9 (4.5)%; p<0.0001). A thickened moderator band was found to be present in similar percentage in ARVC patients and athletes. Conclusions An accurate clinical and instrumental non-invasive evaluation including echocardiography as imaging technique allows to distinguish RV alterations typical of ARVC from those detected in athletes as a consequence of intensive physical activity.

Clinical phenotype and diagnosis of arrhythmogenic right ventricular cardiomyopathy in pediatric patients carrying desmosomal gene mutations

Background Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart muscle disease carrying a risk of sudden death. Information about the clinical features during childhood and the age at disease onset is scanty. Objective The aim of the study was to describe the ARVC phenotype as its initial clinical manifestation in a pediatric population (<18 years) with desmosomal gene mutations. Methods Fifty-three ARVC desmosomal gene mutation carriers (mean age 12.3 ± 3.9 years) were investigated by electrocardiogram (ECG), signal-averaged ECG, 24-hour Holter, echocardiogram, and contrast-enhanced cardiac magnetic resonance (CMR). Results None of the children ≤10 years old fulfilled the 1994 criteria, as opposed to six (33%) aged 11–14 years and eight aged >14 years (42%). At the end of follow-up (9 ± 7 years), 21 (40%) fulfilled the 1994 diagnostic criteria (mean age 16 ± 4 years). By using the 2010 criteria in subjects aged ≤18 years, 53% were unaffected, versus 62% by using the traditional criteria. More than two-thirds of affected subjects had moderate-severe forms of the disease. Contrast-enhanced CMR was performed in 21 (40%); of 13 unaffected gene mutation carriers, six showed ARVC morphological and/or tissue abnormalities. Conclusion In pediatric ARVC mutation carriers, a diagnosis was achieved in 40% of cases, confirming that the disease usually develops during adolescence and young adulthood. The 2010 modified criteria seem to be more sensitive than the 1994 ones in identifying familial pediatric cases. Contrast-enhanced CMR can provide diagnostic information on gene mutation carriers not fulfilling either traditional or modified criteria. Management of asymptomatic gene mutation carriers remains the main clinical challenge.

Identification of a PKP2 gene deletion in a family with arrhythmogenic right ventricular cardiomyopathy.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a primary heart muscle disease characterized by progressive myocardial loss, with fibro-fatty replacement, and high frequency of ventricular arrhythmias that can lead to sudden cardiac death. ARVC is a genetically determined disorder, usually caused by point mutations in components of the cardiac desmosome. Conventional mutation screening of ARVC genes fails to detect causative mutations in about 50% of index cases, suggesting a further genetic heterogeneity. We performed a genome-wide linkage study and a copy number variations (CNVs) analysis, using high−density SNP arrays, in an ARVC family showing no mutations in any of the desmosomal genes. The CNVs analysis identified a heterozygous deletion of about 122 kb on chromosome 12p11.21, including the entire plakophilin-2 gene and shared by all affected family members. It was not listed on any of available public CNVs databases and was confirmed by quantitative real-time PCR. This is the first SNP array-based genome-wide study leading to the identification of a CNV segregating with the disease phenotype in an ARVC family. This result underscores the importance of performing additional analysis for possible genomic deletions/duplications in ARVC patients without point mutations in known disease genes.

Comparison Between QRS Duration at Standard ECG and Signal‐Averaging ECG for Arrhythmic Risk Stratification After Surgical Repair of Tetralogy of Fallot

Introduction: Surgical repair of tetralogy of Fallot is complicated by the occurrence of ventricular tachycardia (VT). Among different indexes proposed to assess prognosis of these patients, the study of QRS and repolarization provided useful information. Controversial results come from the analysis of signal‐averaging ECG (SAECG). The aim of our study was to identify patients operated for tetralogy of Fallot at higher risk of sudden death by means of SAECG.

Phenotypic expression is a prerequisite for malignant arrhythmic events and sudden cardiac death in arrhythmogenic right ventricular cardiomyopathy

AIMS Whether a desmosomal (DS)-gene defect may in itself induce life-threatening ventricular arrhythmias regardless of phenotypic expression of arrhythmogenic right ventricular cardiomyopathy (ARVC) is still debated. This prospective study evaluated the long-term outcome of DS-gene mutation carriers in relation to the ARVC phenotypic expression. METHODS AND RESULTS The study population included 116 DS-gene mutation carriers [49% males; median age 33 years (16-48 years)] without prior sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). The incidence of the arrhythmic endpoint, including sudden cardiac death (SCD), aborted SCD, sustained VT, and appropriate implantable cardioverter-defibrillator (ICD) intervention was evaluated prospectively and stratified by the presence of ARVC phenotype and risk factors (syncope, ventricular dysfunction, and non-sustained VT). At enrolment, 40 of 116 (34%) subjects fulfilled the criteria for definite ARVC while the remaining were either borderline or phenotype negatives. During a median follow-up of 8.5 (5-12) years, 10 patients (9%) had arrhythmic events (0.9%/year). The event rate was 2.3%/year among patients with definite ARVC and 0.2%/year among borderline or phenotype negative patients (P = 0.002). In patients with definite ARVC, the incidence of arrhythmias was higher in those with ≥1 risk factors (4.1%/year) than in those with no risk factors (0.4%/year, P = 0.02). Mortality was 0.2%/year (1 heart failure death and 1 SCD). CONCLUSIONS The ARVC phenotypic expression is a prerequisite for the occurrence of life-threatening arrhythmias in DS-gene mutation carriers. The vast majority of malignant arrhythmic events occurred in patients with an overt disease phenotype and major risk factors suggesting that this subgroup most benefits from ICD therapy.