ROBO4 variants predispose individuals to bicuspid aortic valve and thoracic aortic aneurysm.

Bicuspid aortic valve (BAV) is a common congenital heart defect (population incidence, 1-2%)1-3 that frequently presents with ascending aortic aneurysm (AscAA)4. BAV/AscAA shows autosomal dominant inheritance with incomplete penetrance and male predominance. Causative gene mutations (for example, NOTCH1, SMAD6) are known for ≤1% of nonsyndromic BAV cases with and without AscAA5-8, impeding mechanistic insight and development of therapeutic strategies. Here, we report the identification of variants in ROBO4 (which encodes a factor known to contribute to endothelial performance) that segregate with disease in two families. Targeted sequencing of ROBO4 showed enrichment for rare variants in BAV/AscAA probands compared with controls. Targeted silencing of ROBO4 or mutant ROBO4 expression in endothelial cell lines results in impaired barrier function and a synthetic repertoire suggestive of endothelial-to-mesenchymal transition. This is consistent with BAV/AscAA-associated findings in patients and in animal models deficient for ROBO4. These data identify a novel endothelial etiology for this common human disease phenotype.

Pulsed Discharge Helium Ionization Detector for Highly Sensitive Aquametry.

Trace moisture quantitation is crucial in medical, civilian and military applications. Current aquametry technologies are limited by the sample volume, reactivity, or interferences, and/or instrument size, weight, power, cost, and complexity. We report for the first time on the use of a pulsed discharge helium ionization detector (PDHID-D2) (∼196 cm(3)) for the sensitive (limit of detection, 0.047 ng; 26 ppm), linear (r(2) >0.99), and rapid (< 2 min) quantitation of water using a small (0.2 - 5.0 µL) volume of liquid or gas. The relative humidity sensitivity was 0.22% (61.4 ppmv) with a limit of detection of less than 1 ng moisture with gaseous samples. The sensitivity was 10 to 100 to fold superior to competing technologies without the disadvantages inherent to these technologies. The PDHID-D2, due to its small footprint and low power requirement, has good size, weight, and power-portability (SWAPP) factors. The relatively low cost (∼$5000) and commercial availability of the PDHID-D2 makes our technique applicable to highly sensitive aquametry.

Massive hemoptysis in Loeys-Dietz syndrome.

We describe four unrelated individuals with Loeys-Dietz syndrome (LDS) who presented with massive hemoptysis of unknown etiology. LDS is an autosomal dominant connective-tissue disorder characterized by altered cardiovascular, craniofacial, and skeletal development that is attributed to mutations in the TGFBR1, TGFBR2, SMAD3, or TGFB2 genes. Massive hemoptysis (MH) is a rare and often fatal pulmonary medical emergency. This is the first report of MH in individuals with LDS and establishes it as part of the LDS spectrum. It compels providers to educate their LDS patients on MH, although much investigation needs to be done to determine etiology and appropriate treatment for this newly described LDS feature.

Development of a Mesoscale Pulsed Discharge Helium Ionization Detector for Portable Gas Chromatography.

Miniaturization of gas chromatography (GC) instrumentation enables field detection of volatile organic compounds (VOCs) for chembio-applications such as clandestine human transport and disease diagnostics. We fabricated a mesoscale pulsed discharge helium ionization detector (micro-PDHID) for integrating with our previously described mini-GC hardware. Stainless steel electrodes fabricated by photochemical etching and electroforming facilitated rapid prototyping and enabled nesting of inter-electrode insulators for self-alignment of the detector core during assembly. The prototype was ∼10 cm(3) relative to >400 cm(3) of a commercial PDHID, but with a comparable time to sweep a VOC peak from the detector cell (170 ms and 127 ms, respectively). Electron trajectory modeling, gas flow rate, voltage bias, and GC outlet location were optimized for improving sensitivity. Despite 40-fold miniaturization, the micro-PDHID detected 18 ng of the human emanation, 3-methyl-2-hexenoic acid with <3-fold decrease in sensitivity relative to the commercial detector. The micro-PDHID was rugged and operated for 9 months without failure.

Diltiazem treatment for pre-clinical hypertrophic cardiomyopathy sarcomere mutation carriers: a pilot randomized trial to modify disease expression.

OBJECTIVES: The study sought to assess the safety, feasibility, and effect of diltiazem as disease-modifying therapy for at-risk hypertrophic cardiomyopathy (HCM) mutation carriers. BACKGROUND: HCM is caused by sarcomere mutations and characterized by left ventricular hypertrophy (LVH) with increased risk of heart failure and sudden death. HCM typically cannot be diagnosed early in life, although subtle phenotypes are present. Animal studies indicate that intracellular calcium handling is altered before LVH develops. Furthermore, early treatment with diltiazem appeared to attenuate disease emergence. METHODS: In a pilot, double-blind trial, we randomly assigned 38 sarcomere mutation carriers without LVH (mean 15.8 years of age) to therapy with diltiazem 360 mg/day (or 5 mg/kg/day) or placebo. Treatment duration ranged from 12 to 42 months (median 25 months). Study procedures included electrocardiography, echocardiography, cardiac magnetic resonance imaging, and serum biomarker measurement. RESULTS: Diltiazem was not associated with serious adverse events. Heart rate and blood pressure did not differ significantly between groups. However, mean left ventricular (LV) end-diastolic diameter improved toward normal in the diltiazem group but decreased further in controls (change in z-scores, +0.6 vs. -0.5; p < 0.001). Mean LV thickness-to-dimension ratio was stable in the diltiazem group but increased in controls (-0.02 vs. +0.15; p = 0.04). Among MYBPC3 mutation carriers, LV wall thickness and mass, diastolic filling, and cardiac troponin I levels improved in those taking diltiazem compared with controls. Four participants developed overt HCM, 2 in each treatment group. CONCLUSIONS: Pre-clinical administration of diltiazem is safe and may improve early LV remodeling in HCM. This novel strategy merits further exploration. (Treatment of Preclinical Hypertrophic Cardiomyopathy With Diltiazem; NCT00319982).

The SMAD-binding domain of SKI: a hotspot for de novo mutations causing Shprintzen-Goldberg syndrome.

Shprintzen-Goldberg syndrome (SGS) is a rare, systemic connective tissue disorder characterized by craniofacial, skeletal, and cardiovascular manifestations that show a significant overlap with the features observed in the Marfan (MFS) and Loeys-Dietz syndrome (LDS). A distinguishing observation in SGS patients is the presence of intellectual disability, although not all patients in this series present this finding. Recently, SGS was shown to be due to mutations in the SKI gene, encoding the oncoprotein SKI, a repressor of TGFß activity. Here, we report eight recurrent and three novel SKI mutations in eleven SGS patients. All were heterozygous missense mutations located in the R-SMAD binding domain, except for one novel in-frame deletion affecting the DHD domain. Adding our new findings to the existing data clearly reveals a mutational hotspot, with 73% (24 out of 33) of the hitherto described unrelated patients having mutations in a stretch of five SKI residues (from p.(Ser31) to p.(Pro35)). This implicates that the initial molecular testing could be focused on mutation analysis of the first half of exon 1 of SKI. As the majority of the known mutations are located in the R-SMAD binding domain of SKI, our study further emphasizes the importance of TGFß signaling in the pathogenesis of SGS.

Subtle abnormalities in contractile function are an early manifestation of sarcomere mutations in dilated cardiomyopathy.

BACKGROUND: Sarcomere mutations cause both dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM); however, the steps leading from mutation to disease are not well described. By studying mutation carriers before a clinical diagnosis develops, we characterize the early manifestations of sarcomere mutations in DCM and investigate how these manifestations differ from sarcomere mutations associated with HCM. METHODS AND RESULTS: Sixty-two genotyped individuals in families with sarcomeric DCM underwent clinical evaluation including strain echocardiography. The group included 12 subclinical DCM mutation carriers with normal cardiac dimensions and left ventricular ejection fraction (LVEF ≥55%), 21 overt DCM subjects, and 29 related mutation (-) normal controls. Results were compared with a previously characterized cohort of 60 subclinical HCM subjects (sarcomere mutation carriers without left ventricular hypertrophy). Systolic myocardial tissue velocity, longitudinal, circumferential, and radial strain, and longitudinal and radial strain rate were reduced by 10%-23% in subclinical DCM mutation carriers compared with controls (P<0.001 for all comparisons), after adjusting for age and family relations. No significant differences in diastolic parameters were identified comparing the subclinical and control cohorts. The opposite pattern of contractile abnormalities with reduced diastolic but preserved systolic function was seen in subclinical HCM. CONCLUSIONS: Subtle abnormalities in systolic function are present in subclinical DCM mutation carriers, despite normal left ventricular size and ejection fraction. In contrast, impaired relaxation and preserved systolic function appear to be the predominant early manifestations of sarcomere mutations that lead to HCM. These findings support the theory that the mutation's intrinsic impact on sarcomere function influences whether a dilated or hypertrophic phenotype develops.

Aortic function: from the research laboratory to the clinic.

For many years, much of the pioneering research on aortic function was carried out by a small group of investigators frequently working away from the clinical environment in the research laboratory. The evaluation of aortic function using aortic pulse wave velocity, aortic distensibility, or other practical indices had yet to reach clinical threshold. It was necessary for the clinicians to take over and to apply these indices to the clinic. In this Odyssey, the work by the basic scientist was important to define the fundamental mechanisms of aortic function; however, it was the vision of the clinical investigator who recognized the importance of aortic function and introduced it into clinical practice. In the near future, the clinical investigator will introduce aortic function in daily clinical practice as the measurement of left ventricular function is used today. A close collaboration between the clinical and the basic investigator will be necessary in order to define the molecular mechanisms related to aortic wall synthesis and degradation of collagen and elastin. Application of these findings by the clinical investigator may help to delay or prevent aortic dysfunction related to aging or other conditions and diseases.

Truncations of titin causing dilated cardiomyopathy.

BACKGROUND: Dilated cardiomyopathy and hypertrophic cardiomyopathy arise from mutations in many genes. TTN, the gene encoding the sarcomere protein titin, has been insufficiently analyzed for cardiomyopathy mutations because of its enormous size. METHODS: We analyzed TTN in 312 subjects with dilated cardiomyopathy, 231 subjects with hypertrophic cardiomyopathy, and 249 controls by using next-generation or dideoxy sequencing. We evaluated deleterious variants for cosegregation in families and assessed clinical characteristics. RESULTS: We identified 72 unique mutations (25 nonsense, 23 frameshift, 23 splicing, and 1 large tandem insertion) that altered full-length titin. Among subjects studied by means of next-generation sequencing, the frequency of TTN mutations was significantly higher among subjects with dilated cardiomyopathy (54 of 203 [27%]) than among subjects with hypertrophic cardiomyopathy (3 of 231 [1%], P=3×10(-16)) or controls (7 of 249 [3%], P=9×10(-14)). TTN mutations cosegregated with dilated cardiomyopathy in families (combined lod score, 11.1) with high (>95%) observed penetrance after the age of 40 years. Mutations associated with dilated cardiomyopathy were overrepresented in the titin A-band but were absent from the Z-disk and M-band regions of titin (P≤0.01 for all comparisons). Overall, the rates of cardiac outcomes were similar in subjects with and those without TTN mutations, but adverse events occurred earlier in male mutation carriers than in female carriers (P=4×10(-5)). CONCLUSIONS: TTN truncating mutations are a common cause of dilated cardiomyopathy, occurring in approximately 25% of familial cases of idiopathic dilated cardiomyopathy and in 18% of sporadic cases. Incorporation of sequencing approaches that detect TTN truncations into genetic testing for dilated cardiomyopathy should substantially increase test sensitivity, thereby allowing earlier diagnosis and therapeutic intervention for many patients with dilated cardiomyopathy. Defining the functional effects of TTN truncating mutations should improve our understanding of the pathophysiology of dilated cardiomyopathy. (Funded by the Howard Hughes Medical Institute and others.).

Heritable cardiac conduction and myocardial disease: from the clinic to the basic science laboratory and back to the clinic.

A close collaboration between the physicians-scientists of the Division of Cardiology, The Ohio State University and the basic scientists of the Department of Genetics, Harvard Medical School was essential to define the multiple phenotypic expressions and the genetic abnormalities in the heritable conduction and myocardial disease in a family from central Ohio (Family OSU). The Family OSU presents evidence of sequential hierarchical progression through multiple cardiac phenotypes (sinus bradycardia, atrioventricular conduction defects requiring pacemaker, supraventricular arrhythmias including atrial fibrillation, heart failure, and sudden cardiac death) on a decade-to-decade basis. In this setting, each phenotype may be mistakenly considered as a specific diagnosis by physicians working without a pedigree or long-term follow-up. Genetic analysis, however, confirms lamin A/C mutation. The role of the physician-scientist and the basic scientist for the study of heritable disorders is equally important but different. Only the physician-scientist, however, who is in constant contact with the patient understands the complexity of the disease. The physician-scientist with an interest in a particular disease can guide the basic scientist to define molecular mechanisms of that disease and by extension learn important lessons for other diseases.

Short communication: the cardiac myosin binding protein C Arg502Trp mutation: a common cause of hypertrophic cardiomyopathy.

RATIONALE: The myosin-binding protein C isoform 3 (MYBPC3) variant Arg502Trp has been identified in multiple hypertrophic cardiomyopathy (HCM) cases, but compelling evidence to support or refute the pathogenicity of this variant is lacking. OBJECTIVE: To determine the prevalence, origin and clinical significance of the MYBPC3 Arg502Trp variant. METHODS AND RESULTS: The prevalence of MYBPC3 Arg502Trp was ascertained in 1414 sequential HCM patients of primarily European descent. MYBPC3 Arg502Trp was identified in 34 of these 1414 unrelated HCM patients. Segregation of MYBPC3 Arg502Trp with clinical status was assessed in family members. Disease haplotypes were examined in 17 families using two loci flanking MYBPC3. Family studies identified an additional 43 variant carriers, many with manifest disease, yielding a calculated odds ratio of 11 000:1 for segregation of MYBPC3 Arg502Trp with HCM. Analyses in 17 families showed at least 4 independent haplotypes flanked MYBPC3 Arg502Trp. Eight individuals (4 probands and 4 family members) also had another sarcomere protein gene mutation. Major adverse clinical events occurred in approximately 30% of MYBPC3 Arg502Trp carriers by age 50; these were significantly more likely (P<0.0001) when another sarcomere mutation was present. CONCLUSIONS: MYBPC3 Arg502Trp is the most common and recurrent pathogenic mutation in a diverse primarily European descent HCM cohort, occurring in 2.4% of patients. MYBPC3 Arg502Trp conveys a 340-fold increased risk for HCM by 45 years of age, when more than 50% of carriers have overt disease. HCM prognosis worsens when MYBPC3 Arg502Trp occurs in the setting of another sarcomere protein gene mutation.

Familial dilated cardiomyopathy caused by an alpha-tropomyosin mutation: the distinctive natural history of sarcomeric dilated cardiomyopathy.

OBJECTIVES: We sought to further define the role of sarcomere mutations in dilated cardiomyopathy (DCM) and associated clinical phenotypes. BACKGROUND: Mutations in several contractile proteins contribute to DCM, but definitive evidence for the roles of most sarcomere genes remains limited by the lack of robust genetic support. METHODS: Direct sequencing of 6 sarcomere genes was performed on 334 probands with DCM. A novel D230N missense mutation in the gene encoding alpha-tropomyosin (TPM1) was identified. Functional assessment was performed by the use of an in vitro reconstituted sarcomere complex to evaluate ATPase regulation and Ca(2+) affinity as correlates of contractility. RESULTS: TPM1 D230N segregated with DCM in 2 large unrelated families. This mutation altered an evolutionarily conserved residue and was absent in >1,000 control chromosomes. In vitro studies demonstrated major inhibitory effects on sarcomere function with reduced Ca(2+) sensitivity, maximum activation, and Ca(2+) affinity compared with wild-type TPM1. Clinical manifestations ranged from decompensated heart failure or sudden death in those presenting early in life to asymptomatic left ventricular dysfunction in those diagnosed during adulthood. Notably, several affected infants had remarkable improvement. CONCLUSIONS: Genetic segregation in 2 unrelated families and functional analyses conclusively establish a pathogenic role for TPM1 mutations in DCM. In vitro results demonstrate contrasting effects of DCM and hypertrophic cardiomyopathy mutations in TPM1, suggesting that specific functional consequences shape cardiac remodeling. Along with previous reports, our data support a distinctive, age-dependent phenotype with sarcomere-associated DCM where presentation early in life is associated with severe, sometimes lethal, disease. These observations have implications for the management of familial DCM.

Cardiovascular nursing on human genomics: what do cardiovascular nurses need to know about congestive heart failure?

This paper presents the main causes of heart failure (HF) and an update on the genetics studies on each cause. The review includes a delineation of the etiology and fundamental pathophysiology of HF and provides rational for treatment for the patient and family. Various cardiomyopathies are discussed, including primary cardiomyopathies, mixed cardiomyopathies, cardiomyopathies that involve altered cardiac muscle along with generalized multiorgan disorders, and various cardiovascular conditions, such as coronary artery disease (ischemic cardiomyopathy) and hypertension (hypertensive cardiomyopathy). A brief review of pharmacogenetics and HF is presented. The application of the genetic components of cardiomyopathy and pharmacogenetics is included to enhance cardiovascular nursing care.

Mutations in smooth muscle alpha-actin (ACTA2) cause coronary artery disease, stroke, and Moyamoya disease, along with thoracic aortic disease.

The vascular smooth muscle cell (SMC)-specific isoform of alpha-actin (ACTA2) is a major component of the contractile apparatus in SMCs located throughout the arterial system. Heterozygous ACTA2 mutations cause familial thoracic aortic aneurysms and dissections (TAAD), but only half of mutation carriers have aortic disease. Linkage analysis and association studies of individuals in 20 families with ACTA2 mutations indicate that mutation carriers can have a diversity of vascular diseases, including premature onset of coronary artery disease (CAD) and premature ischemic strokes (including Moyamoya disease [MMD]), as well as previously defined TAAD. Sequencing of DNA from patients with nonfamilial TAAD and from premature-onset CAD patients independently identified ACTA2 mutations in these patients and premature onset strokes in family members with ACTA2 mutations. Vascular pathology and analysis of explanted SMCs and myofibroblasts from patients harboring ACTA2 suggested that increased proliferation of SMCs contributed to occlusive diseases. These results indicate that heterozygous ACTA2 mutations predispose patients to a variety of diffuse and diverse vascular diseases, including TAAD, premature CAD, ischemic strokes, and MMD. These data demonstrate that diffuse vascular diseases resulting from either occluded or enlarged arteries can be caused by mutations in a single gene and have direct implications for clinical management and research on familial vascular diseases.

Erectile dysfunction in men with congenital heart disease.

There has been a tremendous focus on gynecologic health with the increasing number of women with congenital heart disease (CHD). Conversely, experience in providing sexual health screening to men with CHD is lacking. The purpose of this study was to identify sexual health issues in men with CHD. An anonymous survey was distributed to men in our adult CHD clinic. Age, type of CHD, medications, detailed sexual history including cardiovascular symptoms with intercourse, erectile dysfunction (ED), and willingness to discuss ED with a physician was obtained. A logistic regression analysis was performed to analyze the relation between medications, CHD complexity, and ED; 86 men completed the survey with a mean age of 34 +/- 10 years. The prevalence of ED was 38%. Men were treated with cardiac medications including beta blockers (BB; 24%), angiotensin-converting enzyme (ACE) inhibitors (8%), calcium-channel blockers (6%), and combination BB and ACE inhibitor therapy (16%). Men on BB were 3.13 times more likely to report ED (p = 0.045). Complexity of CHD did not increase the likelihood of ED symptoms (p >0.10). Although most men attributed symptoms to their underlying CHD, most were willing to discuss issues of ED with their cardiologist. In conclusion, ED is prevalent in young men with CHD. Although an emotional component may contribute, certain medications may exacerbate symptoms.

Biobanks and biomarker research in cardiovascular disease.

PURPOSE: The purpose of this article is to describe biobank processes and the sociocultural and nursing challenges of these processes. The article will present ways that thinking genetically can challenge cardiovascular nurses and help in the development of biobanks for cardiovascular research. It will emphasize the importance of the contributions of nursing to the development of biobanks and biobanking research. CONCLUSIONS: The influence of cardiovascular nurses on the development of biobanks for research in cardiovascular disease will result in accelerated discoveries that will lead to innovative, safe, effective therapeutics (translational research and personalized healthcare). The challenge is to educate and encourage clinicians to think genetically and use biobanks for research.

Mid-myocardial fibrosis by cardiac magnetic resonance in patients with lamin A/C cardiomyopathy: possible substrate for diastolic dysfunction.

AIMS: We sought to identify patterns of myocardial fibrosis in vivo in patients with lamin cardiomyopathy, and to determine its functional significance. METHODS AND RESULTS: Eleven patients sharing the identical mutation in LMNA without contraindication to magnetic resonance were identified from a 1016-member pedigree. Eight autopsy hearts from deceased relatives were reviewed. Patients and age-matched controls underwent cardiac magnetic resonance that included measures of cardiac function and late gadolinium enhancement (LGE). LGE-CMR identified midmyocardial fibrosis of the basal interventricular septum in 5 of 11 LMNA patients that was identical to that seen in 6 autopsy specimens of related genotype-positive family members; this was not present in any of 11 controls. LGE-CMR was positive in the 5 oldest patients in the cohort, age 46 +/- 6 years compared to 24 +/- 10 years for LGE-negative subjects (p = 0.003). Systolic function was abnormal in 2 subjects, both with myocardial fibrosis. LGE-positivity distinguished patients with diastolic dysfunction by mitral inflow velocities from those with normal diastolic function; these patients also had significant left atrial enlargement compared to controls (p < 0.05). CONCLUSIONS: LGE-CMR can identify myocardial fibrosis under genetic control in vivo in patients with heritable cardiomyopathy similar in distribution to that observed at autopsy. Mid-myocardial fibrosis may form the substrate for diastolic dysfunction in these patients.

Mutations in smooth muscle alpha-actin (ACTA2) lead to thoracic aortic aneurysms and dissections.

The major function of vascular smooth muscle cells (SMCs) is contraction to regulate blood pressure and flow. SMC contractile force requires cyclic interactions between SMC alpha-actin (encoded by ACTA2) and the beta-myosin heavy chain (encoded by MYH11). Here we show that missense mutations in ACTA2 are responsible for 14% of inherited ascending thoracic aortic aneurysms and dissections (TAAD). Structural analyses and immunofluorescence of actin filaments in SMCs derived from individuals heterozygous for ACTA2 mutations illustrate that these mutations interfere with actin filament assembly and are predicted to decrease SMC contraction. Aortic tissues from affected individuals showed aortic medial degeneration, focal areas of medial SMC hyperplasia and disarray, and stenotic arteries in the vasa vasorum due to medial SMC proliferation. These data, along with the previously reported MYH11 mutations causing familial TAAD, indicate the importance of SMC contraction in maintaining the structural integrity of the ascending aorta.

Association between glycosylated hemoglobin, left ventricular mass and aortic function in nondiabetic individuals with insulin resistance.

OBJECTIVE: An association between glycosylated hemoglobin (GHb) and cardiovascular mortality in nondiabetic individuals has recently been reported. Prompt detection of nondiabetic individuals with high-normal GHb and early cardiovascular involvement may be of value for preventive strategies. In this investigation, a possible relationship between GHb, aortic function and left ventricular (LV) mass in nondiabetic individuals has been studied. METHODS: A total of 263 nondiabetic African-Americans, aged 22-63 (mean 42 +/- 8) years were studied. All individuals were first degree relatives of diabetic patients, had normal oral glucose tolerance test (2-h OGTT) and decreased peripheral action of insulin. LV diameters and mass (echocardiography); ascending and abdominal aortic distensibility (echocardiography, arterial pressure); pulse wave velocity (PWV; electrocardiography, Doppler); fasting glucose; GHb; insulin sensitivity index (S(I)) and 2-h OGTT were measured. Multiple linear and logistic regression analyses were used to identify significant independent associations of fasting glucose; GHb; S(I) and 2-h OGTT with aortic function and LV mass. RESULTS: In fully adjusted multivariate logistic regression analysis, GHb predicted lower values of aortic distensibility (odds ratio (OR) 1.67 95% CI (1.04-2.75), P=0.04); higher PWV (OR 1.79 95% CI (1.09-2.93), P=0.022); and higher values of LV mass (OR 1.56 95% CI (1.08-2.88), P=0.029). Fasting glucose, S(I), and 2 h OGTT were not associated with aortic function and LV mass. CONCLUSION: Higher GHb concentrations, even within 'normal' range, are independently associated with stiffer aorta and increased LV mass and thus may detect nondiabetic individuals at increased cardiovascular risk.