Serial Observations and Mutational Analysis of an Adoptee with Family History of Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an inherited cardiac disease with an autosomal dominant mode of transmission. Comprehensive genetic screening of several genes frequently found mutated in HCM is recommended for first-degree relatives of HCM patients. Genetic testing provides the means to identify those at risk of developing HCM and to institute measures to prevent sudden cardiac death (SCD). Here, we present an adoptee whose natural mother and maternal relatives were known be afflicted with HCM and SCD. The proband was followed closely from age 6 to 17 years, revealing a natural history of the progression of clinical findings associated with HCM. Genetic testing of the proband and her natural mother, who is affected by HCM, revealed that they were heterozygous for both the R719Q and T1513S variants in the cardiac beta-myosin heavy chain (MYH7) gene. The proband's ominous family history indicates that the combination of the R719Q and T1513S variants in cis may be a “malignant” variant that imparts a poor prognosis in terms of the disease progression and SCD risk

Sympathetic nervous system alterations with HER2+ antagonism: an early marker of cardiac dysfunction with breast cancer treatment?

BACKGROUND: HER2 antagonists (anti-HER2; e.g., trastuzumab and lapatinib) are effective in treating an aggressive form of breast cancer (BC), but can cause cardiotoxicity due to the disruption in neuregulin (NRG)/HER2+ ligand receptor signalling. The recent data show that NRG-HER2 receptors located in the medulla oblongata are important regulators of vasomotor tone. Disrupting the NRG-HER2 signalling in mouse medulla results in increased sympathetic nerve output and blood pressure. We hypothesized that anti-HER2 agents would cause increased sympathetic tone with changes in plasma catecholamines and NRG. METHODS: In 15 newly diagnosed HER2+ BC patients receiving anti-HER2 agents, vital signs were measured along with supine plasma epinephrine (EPI), norepinephrine (NE), and NRG at baseline and three months. Serial echocardiography was performed. RESULTS: With three months of anti-HER2 treatment, NE increased (2.334 ± 1.294 nmol/L vs. 3.262 ± 2.103 nmol/L; p = 0.004) and NRG decreased (12.7±15.7 ng/ml vs. 10.9 ± 13.3 ng/ml; p = 0.036) with a corresponding increase in systolic blood pressure (110 ± 10 mmHg vs. 120 ± 16 mmHg, p = 0.049) and diastolic blood pressure (67 ± 14 vs. 77 ± 10, p = 0.009). There was no change, however, in EPI (0.183 ± 0.151 nmol/L vs. 0.159 ± 0.174 nmol/L; p = 0.519) or heart rate (73 ± 12 bpm vs. 77 ± 10 bpm, p = 0.146). Left ventricular ejection function declined over the follow-up period (baseline 63 ± 6% vs. follow-up 56 ± 5%). CONCLUSIONS: Anti-HER2 treatment results in increased NE, blood pressure, and decreased NRG; this suggests that the inhibition of NRGHER2 signalling leads to increased sympathoneural tone. Larger studies are needed to determine if these observations have prognostic value and may be offset with medical interventions, such as beta-blockers. CLINICAL TRIAL REGISTRATION: The study was registered with www.clinicaltrials.gov (NCT00875238)

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Hypertrophic cardiomyopathy (HCM) is an inherited cardiac disease with an autosomal dominant mode of transmission. Comprehensive genetic screening of several genes frequently found mutated in HCM is recommended for first-degree relatives of HCM patients. Genetic testing provides the means to identify those at risk of developing HCM and to institute measures to prevent sudden cardiac death (SCD). Here, we present an adoptee whose natural mother and maternal relatives were known be afflicted with HCM and SCD. The proband was followed closely from age 6 to 17 years, revealing a natural history of the progression of clinical findings associated with HCM. Genetic testing of the proband and her natural mother, who is affected by HCM, revealed that they were heterozygous for both the R719Q and T1513S variants in the cardiac beta-myosin heavy chain (MYH7) gene. The proband's ominous family history indicates that the combination of the R719Q and T1513S variants in cis may be a "malignant" variant that imparts a poor prognosis in terms of the disease progression and SCD risk

Circulating neuregulin during the transition from stage A to stage B/C heart failure in a breast cancer cohort.

BACKGROUND: Breast cancer (BC) treatments can cause heart failure (HF) in a subset of patients. ACC/AHA guidelines classify patients receiving cardiotoxic medications as stage A, a high-risk population for the development of HF. Circulating neuregulin (NRG) correlates with outcomes in stage C and D HF. We examined the levels of NRG in a BC cohort receiving cardiotoxic chemotherapy and its relationship with adverse cardiac effects during the transition from stage A to stage B or C HF. METHODS AND RESULTS: In an ongoing prospective study, a planned interim analysis of 78 BC women receiving either anthracycline (AC) or trastuzumab (Tsz) was performed. Biometric data, cardiac risk factors, and NRG levels, were collected before chemotherapy and after completion of AC therapy and/or 3 months into Tsz therapy. Cardiac function was measured by left ventricular ejection fraction (LVEF) by echocardiography at the above time points and longitudinally as standard of care. The interim cohort was predominately white with stage II BC and a median age of 50 years. A reduction of \u3e10 absolute percentage points in LVEF was observed in 21.4% of the cohort, representing a transition from stage A to stage B or C HF. A statistically significant drop in plasma NRG was observed in women treated with AC and/or Tsz (P \u3c .001). Additionally, baseline NRG correlated with the maximal change in LVEF. CONCLUSIONS: More than 20% of women experienced cardiac dysfunction, detected by decline in LVEF, and were reclassified as stage B or C HF. Plasma NRG levels were reduced after exposure to cardiotoxic chemotherapy, suggesting a loss in a cardioprotective growth factor. Higher baseline NRG levels were observed in those with the greatest decline in LVEF, supporting the continued investigation of NRG as a potential prognostic marker in early-stage HF

Neuregulin-1β regulation of embryonic endothelial progenitor cell survival

Endothelial progenitor cells (EPCs) are mobilized into the vascular space and home to damaged tissues, where they promote repair in part through a process of angiogenesis. Neuregulins (NRGs) are ligands in the epidermal growth factor family that signal through type I receptor tyrosine kinases in the erbB family (erbB2, erbB3, and erbB4) and regulate endothelial cell biology, promoting angiogenesis. Stimuli such as ischemia and exercise that promote EPC mobilization also induce cleavage and release of transmembrane NRG from cardiac microvascular endothelial cells (CMECs). We hypothesized that NRG/erbB signaling may regulate EPC biology. Using an embryonic (e)EPC cell line that homes to and repairs injured myocardium, we were able to detect erbB2 and erbB3 transcripts. Identical receptor expression was found in EPCs isolated from rat bone marrow and human whole blood. NRG treatment of eEPCs induces phosphorylation of kinases including Akt, GSK-3β, and Erk1/2 and the nuclear accumulation and transcriptional activation of β-catenin. NRG does not induce eEPC proliferation or migration but does protect eEPCs against serum deprivation-induced apoptosis. These results suggest a role for tissue-derived NRG in the regulation of EPC survival