Genetics of hypertrophic cardiomyopathy: A review of current state.

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiovascular disease. HCM is a highly complex and heterogeneous disease regarding not only the number of associated mutations but also the severity of phenotype, symptom burden, and the risk of complications, such as heart failure and sudden death. The penetrance is incomplete and it is age and gender dependent. It is accepted as a disease of the sarcomere. Sixty percent of HCM cases carry mutations in 1 of 8 sarcomere protein genes, mainly non-sense MYBPC3 and missense MYH7 variants. Young patients with severe phenotype and other clinical features are included in proposed scores for prediction of high positive genetic result. The number of genes reported as disease-causing has increased in the last few years, in some cases without robust evidence. Currently available in silico tools are not always useful for differentiation between benign and deleterious variants. There is enough information on genotype-phenotype correlations to start understanding the mechanisms of the disease. Genetic and environmental modifiers have been explored with some interesting insights from miRNA studies with potential as biomarkers and therapeutic agents. There is an additional value of genetic testing in HCM for prognosis. Knowledge about genetics and functional studies are the basis of near future therapies.

Unclassifiable arrhythmic cardiomyopathy associated with Emery-Dreifuss caused by a mutation in FHL1.

Emery-Dreifuss muscular dystrophy (EDMD) is a heterogeneous genetic disorder characterized by peripheral muscular weakness often associated with dilated cardiomyopathy. We characterize clinically a large family with a mutation in FHL1 gene (p.Cys255Ser). Penetrance was 44%, 100% for males and 18% for females. The heart was the main organ involved. Affected adult males had mild hypertrophy, systolic dysfunction and restriction with non-dilated ventricles. Carriers had significant QTc prolongation. The proband presented with resuscitated cardiac arrest. There were two transplants. Pathological study of explanted heart showed fibrofatty replacement and scarring consistent with arrhythmogenic cardiomyopathy and prominent left ventricular trabeculations. Myopathic involvement was evident in all males. Females had no significant neuromuscular disease. Mutations in FHL1 cause unclassifiable cardiomyopathy with coexisting EDMD. Prognosis is poor and systolic impairment and arrhythmias are frequent. Thrombopenia and raised creatine phosphokinase should raise suspicion of an FHL-1 disorder in X-linked cardiomyopathy.

A mutation in the Z-line Cypher/ZASP protein is associated with arrhythmogenic right ventricular cardiomyopathy.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an important cause of malignant arrhythmia and sudden death particularly in young people. Although it is considered a desmosomal disease, mutations in non-desmosomal genes have also been identified. We report on a family where a mutation in LDB3 is associated with this condition. The index case and first and second degree relatives underwent a complete clinical evaluation: physical examination, electrocardiography (ECG), signal-averaged ECG, 2D echocardiogram, cardiac magnetic resonance and 24-h monitoring. After ruling out mutations in the five desmosomal genes, genetic testing by means of Next Generation Sequencing was carried out on the proband. A heterozygous missense mutation in LDB3 c.1051A>G was identified. This result was confirmed by subsequent Sanger DNA sequencing. Another six carriers were identified amongst her relatives. Three subjects fulfilled the criteria for a definitive diagnosis of ARVC and one reached a borderline diagnosis. In conclusion, this is the first family with ARVC where a mutation in LDB3 is associated with ARVC. Next generation sequencing arises as a particular useful tool to point to new causative genes in ARVC.

A study of the SCN5A gene in a cohort of 76 patients with Brugada syndrome.

We aim to study the SCN5A gene in a cohort of Brugada syndrome (BS) patients and evaluate the genotype-phenotype correlation. BS is caused by mutations in up to 10 different genes, SCN5A being the most frequently involved. Large genomic rearrangements in SCN5A have been associated with conduction disease, but its prevalence in BS is unknown. Seventy-six non-related patients with BS were studied. Clinical characteristics and family risk profile were recorded. Direct sequencing and multiplex ligation-dependent probe amplification (MLPA) of the SCN5A gene for identification of mutations and larger rearrangements were performed, respectively. Eight patients (10.5%) had point mutations (R27H, E901K, G1743R (detected in three families), V728I, N1443S and E1152X). Patients with mutations had a trend toward a higher proportion of spontaneous type I Brugada electrocardiogram (ECG) (87.5% vs 52.9%, p = 0.06) and had evidence of familial disease (62.5%, vs 23.5%, p = 0.03). The symptoms and risk profile of the carriers were not different from wild-type probands. There were non-significant differences in the prevalence of type I ECG, syncope and history of arrhythmia in carriers of selected polymorphisms. None of the patients had any deletion/duplication in the SCN5A gene. In conclusion, 10.5% of our patients had mutations in the SCN5A gene. Patients with mutations seemed to have more spontaneous type I ECG, but no differences in syncope or arrhythmic events compared with patients without mutations. Larger studies are needed to evaluate the role of polymorphisms in the SCN5A in the expression of the phenotype and prognosis. Large rearrangements were not identified in the SCN5A gene using the MLPA technique.

Efficacy of percutaneous closure of patent foramen ovale: comparison among three commonly used occluders.

BACKGROUND: Percutaneous closure of patent foramen ovale (PFO) is standard treatment for patients with paradoxical embolism but studies examining the efficacy of the various occluders are lacking. OBJECTIVE: To evaluate short- and medium-term closure rates of three common occluders. METHODS: One hundred and sixty-six adults (47±12 (18-81 years)) were evaluated with transthoracic bubble echocardiography before and after PFO closure. Only patients with large PFOs were included (>30 bubbles in the left heart after Valsalva). RESULTS: Three occluders were used: Amplatzer (AGA Medical Corporation) (n=80, 48%), Gore Helex (n=48, 29%) and Premere TM (St Jude Medical) (n=38, 23%). One (0.6%) neurological event occurred during follow-up. At 6 months significant residual shunting after Valsalva was highest in the group that received the Helex (58.3%), and lower for Premere (39.5%) and Amplatzer (32.5%). At final follow-up residual shunting remained higher in patients with the Helex (33.3%) than in Premere (18.5%) and Amplatzer (11%). Amplatzer had a significantly lower residual shunt rate than Helex (p<0.05 at 6 months and final follow-up). The Premere had an intermediate residual shunt rate. Septal aneurysm also predicted residual shunting (RR=24.7, 95% CI: 8.2 to 74.4, p<0.0001). CONCLUSIONS: Percutaneous PFO closure is an efficacious progressive treatment but closure rates also depend on the presence of aneurysm and differ between occluders.

Insights into the role of microRNAs in cardiac diseases: from biological signalling to therapeutic targets.

microRNAs have recently opened new pathways to explain gene expression and disease biology in many scenarios, including cardiac diseases. microRNAs are endogenous small non-coding RNAs that mediate post-transcriptional repression or messenger RNA degradation. By annealing to inexactly complementary sequences in the 3' untranslated region of the target messenger RNA, protein level is down-regulated. Several microRNAs appear to act cooperatively through multiple target sites in one gene and, conversely, most microRNAs can target several genes. miR-133 and miR-1 are specifically expressed in cardiac and skeletal muscle and control myogenesis, cardiac development, cardiac performance and cardiomyocyte hypertrophy (mainly by tuning transcription factors and other growth-related targets). They also modulate the expression of certain cardiac ion channels and related proteins with proarrhythmic effect. Besides them, other microRNAs have been shown to exert influence on the myocardial growth, the electrical balance and the angiogenesis processes that take place in the heart. Bioinformatics is a useful tool to identify potential targets of a given microRNA, although there is still substantial concern about their reliability. Experimental manipulation of microRNAs has provided a tantalizing basis to speculate that future research on microRNAs may yield important progress in the prevention of sudden cardiac death and in the treatment of cardiac heart failure. However, the final effect of the blockage of microRNAs in vivo remains unclear, since each of them can target hundreds of genes with different intensity. The era of the microRNAs in cardiovascular diseases has just started.

[Ophthalmological manifestations in Fabry's disease. Four clinical cases showing deficient alpha-galactosidase-A activity]. / Manifestaciones oftalmológicas en la enfermedad de Fabry. A propósito de 4 casos con actividad deficiente de a-galactosidasa A.

CASE REPORT: Fabry's disease is an illness produced by an alteration in the catabolism of the glycosphingolipids. We report ophthalmologic findings in 4 people, detected after 113 patient evaluations from an analytical, cardiological and genetic point of view. DISCUSSION: Fabry's disease is uncommon and shows variable ophthalmologic affectation. Some patients with Fabry's disease do not present ocular affectation, while, on the other hand, healthy carriers with important ocular alterations have been described. The deposit of glycosphingolipids produces affectation at the corneal, crystalline, vascular and retinal levels. The vascular alterations affect not only the veins but also the arteries, as we report in our patients.

Historical trends in reported survival rates in patients with hypertrophic cardiomyopathy.

OBJECTIVE: To determine the range of survival rates of patients with hypertrophic cardiomyopathy (HCM) by comparing and contrasting the natural history of a cohort of patients seen between 1988 and 2002 with that of other published series. METHODS: 956 adult (> or = 16 years old) patients with HCM (572 men, mean (SD) age 42 (15) years, range 16-88) were evaluated by ECG, Holter, exercise testing, and echocardiography. Patient characteristics and survival data were compared with those in natural history studies from referral and non-referral centres published between 1960 and January 2003. RESULTS: The duration of follow up was 69 (45) months. 120 (12.6%) patients died or underwent cardiac transplantation. Sudden cardiac death (n = 48) was the most common mode of death. The annual rate of sudden death or implantable cardioverter-defibrillator discharge was 1.02 (95% confidence interval (CI) 0.76 to 1.26). Annual rates for heart failure death or transplantation and stroke related death were 0.55% (95% CI 0.37% to 0.78%) and 0.07% (95% CI 0.02% to 0.19%), respectively. When studies published within the last 10 years of the study period were compared with earlier reports, the size of individual study cohorts was larger (309 (240.6) v 136.5 (98.8), p = 0.058) and the proportion with severe functional limitation NYHA class III/IV lower (12.4% v 24.8%, p < 0.0001), and fewer patients underwent septal myotomy-myectomy (5.2% v 18.7%, p < 0.0001). Published sudden death rates over the last 10 years were lower than previously published figures (median 1.0% (range 0.1-1.7) v 2.0% (0-3.5)). CONCLUSION: Published survival rates in HCM cohorts have improved progressively over the past 40 years. In the modern era the prevalence of disease related complications is similar in all reporting centres.

Prevalence and clinical significance of systolic impairment in hypertrophic cardiomyopathy.

OBJECTIVES: To determine the frequency of systolic impairment (SI) and its impact on the natural history of hypertrophic cardiomyopathy (HCM). METHODS: 1080 patients (mean (SD) age 43 (15) years, 660 men) with HCM were evaluated. Initial assessment included history, examination, 48 hour Holter monitoring, cardiopulmonary exercise testing, and echocardiography; SI was defined as a fractional shortening (FS) < or = 25%. Survival data were collected at clinic visits or by direct communication with patients and their general practitioners. The results of serial echocardiography in 462 patients with normal FS at presentation are also reported. RESULTS: 26 (2.4%) patients (49 (14) years, 18 men) had SI at the initial visit. During follow up (58 (49) months), nine (34.6%) died or underwent cardiac transplantation compared with 108 (10.2%) patients with normal FS (p = 0.01). Five year survival from death (any cause) or transplantation was 90.1% (95% confidence interval (CI) 87.8 to 92.4) in patients with normal systolic function versus 52.4% (95% CI 25.2 to 79.6, p < 0.0001) in patients with SI. In patients who underwent serial echocardiography, 22 (4.8%, aged 41 (15) years) developed SI over 66 (40) months; the annual incidence of SI was 0.87% (95% CI 0.54 to 1.31). On initial evaluation patients who developed SI had a higher frequency of syncope (67 (15.2%) v 10 (45.5%) of those who did not develop SI, p = 0.001), non-sustained ventricular tachycardia (91 (20.6%) v 11 (50%), p = 0.002), and an abnormal blood pressure response on exercise (131 (29.7%) v 15 (68.2%), p = 0.001). Patients with SI had greater wall thinning (p = 0.001), left ventricular cavity enlargement (p < 0.0005), and deterioration in New York Heart Association functional class (p = 0.001) during follow up. Thirteen (59.1%) patients who progressed to SI died or underwent transplantation compared with 38 (8.6%) patients who maintained normal systolic function. CONCLUSIONS: SI is an infrequent complication of HCM but, when present, is associated with a poor prognosis.

Pregnancy related complications in women with hypertrophic cardiomyopathy.

OBJECTIVES: To determine whether pregnancy is well tolerated in hypertrophic cardiomyopathy. SETTING: Referral clinic. DESIGN: The study cohort comprised 127 consecutively referred women with hypertrophic cardiomyopathy. Forty (31.5%) underwent clinical evaluation before pregnancy. The remaining 87 (68.5%) were referred after their first pregnancy. All underwent history, examination, electrocardiography, and echocardiography. Pregnancy related symptoms and complications were determined by questionnaire and review of medical and obstetric records where available. RESULTS: There were 271 pregnancies in total. Thirty six (28.3%) women reported cardiac symptoms in pregnancy. Over 90% of these women had been symptomatic before pregnancy. Symptoms deteriorated during pregnancy in fewer than 10%. Of the 36 women with symptoms during pregnancy, 30 had further pregnancies. Symptoms reoccurred in 18 (60%); symptomatic deterioration was not reported. Heart failure occurred postnatally in two women (1.6%). No complications were reported in 19 (15%) women who underwent general anaesthesia and in 22 (17.4%) women who received epidural anaesthesia, three of whom had a significant left ventricular outflow tract gradient at diagnosis after pregnancy. Three unexplained intrauterine deaths occurred in women taking cardiac medication throughout pregnancy. No echocardiographic or clinical feature was a useful indicator of pregnancy related complications. CONCLUSIONS: Most women with hypertrophic cardiomyopathy tolerate pregnancy well. However, rare complications can occur and therefore planned delivery and fetal monitoring are still required for some patients.

Soluble and particulate organophosphorus neuropathy target esterase in brain and sciatic nerve of the hen, cat, rat, and chick.

Considerable evidence exists suggesting that the so-called neuropathy target esterase (NTE) is involved in the mechanisms responsible for organophosphorus-induced delayed polyneuropathy (OPIDP). Earlier studies in the adult hen, the habitually employed experimental model in OPIDP, have shown that most NTE activity in the brain is centered in particulate fractions, whereas approximately 50% of this activity in the sciatic nerve is encountered in soluble form, with the rest being particulate NTE. In the present work, we have studied the particulate and soluble fractional distribution of paraoxon-resistant phenylvalerate esterase activity (B activity), paraoxon- and mipafox-resistant phenylvalerate esterase activity (C activity), and NTE activity (B-C) according to ultracentrifugation criteria (100,000 g for 1 h). To this effect, two sensitive (adult hen and cat) and two scarcely sensitive (rat and chick) models were used. In all four experimental models, the distribution pattern was qualitatively similar: B activity and total NTE were much greater in brain (900-2,300 nmol/min/g of tissue) than in sciatic nerve (50-100 nmol/min/g of tissue). The proportion of soluble NTE in brain was very low (< 2%), whereas its presence in sciatic nerve was substantial (30-50%). The NTE/B ratio in brain was high for the particulate fraction (> 60%) and low in the soluble fraction (7-30%); in sciatic nerve the ratio was about 50% in both fractions.(ABSTRACT TRUNCATED AT 250 WORDS)