Gene/Protein Disease Symptom Drug Enzyme Compound
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An elderly woman who had been receiving long-term oral anticoagulant therapy developed skin and subcutaneous fat necrosis on five repeated occasions of extreme hypocoagulability, associated with coinciding periods of congestive cardiac failure. In each episode, the skin necrosis developed within days after the prothrombin time (as determined with Thrombotest) exceeded 200 s (International Normalized Ratio greater than 5.4). Widespread thrombosis in the subcutaneous vasculature and interstitial bleeding, as observed in a skin biopsy specimen, were consistent with a diagnosis of coumarin necrosis. On two occasions, an acquired functional protein C deficiency was present. It is hypothesized that an imbalance between anticoagulant and procoagulant vitamin K-dependent factors contributed to the pathogenesis of coumarin-induced skin necrosis. This imbalance was related to repeated periods of congestive heart failure.
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PMID:Recurrent coumarin-induced skin necrosis in a patient with an acquired functional protein C deficiency. 378 74

Recurrent venous thrombotic and thromboembolic disease, once thought to be an uncommon entity, is increasingly being recognized. Etiologies of recurrent deep venous thrombosis usually include elements of Virchow's triad. Venous stasis (e.g., immobilization, congestive heart failure, acute myocardial infarction, obesity), hypercoagulability (e.g., malignancy, inflammatory bowel disease, hyperhomocysteinemia, protein C resistance, antithrombin III, protein C or S deficiency) and endothelial trauma (e.g., surgical trauma, venous trauma, in-dwelling venous instrumentation) are risk factors. Diagnosis is dependent on objective testing, including venography duplex Doppler (color) ultrasonography and impedance plethysmography. Treatment is usually started with heparin or low-molecular-weight heparin and advanced to warfarin (adjusted to international normalized ratio). Prophylaxis may continue using low-molecular-weight heparin, warfarin, venacaval interruption (Greenfield filter), or concomitant use of the platelet-active agent indobufen and graduated compression stockings.
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PMID:Clinical therapeutic conference: recurrent venous thrombotic and thromboembolic disease. 1009 38

Thrombophilia is defined as an increased tendency to thrombosis and can be inherited or acquired. The thrombotic events in patients with inherited thrombophilia tend to occur at a young age, are often idiopathic, recurrent and may occur at unusual sites (e.g. mesenteric, portal and cerebral veins and in inferior vena cava). The most common of the hereditary defects appear to be antithrombin, protein C, protein S deficiency, which account for 10% of individuals presenting with venous thromboembolism, resistance to anticoagulant effect of activated protein C (APC-R), which is present in 17 to 64% of patients with thrombosis and prothrombin 20210 G-->A variant with 6% prevalence in patients with thrombosis. APC-R is due in 90% to the presence of factor V Leiden. Rarer defects include heparin cofactor II (HC II), plasminogen or tissue plasminogen activator deficiency (TPA), elevated plasminogen activator inhibitor-1 (PAI-1) and dysfibrinogenemia. The most common acquired defects are antiphospholipid antibodies (lupus anticoagulant and anticardiolipin antibodies). Hyperhemocystinemia is responsible as well for arterial as venous thrombosis. A substantial proportion of venous thrombotic events occurs spontaneously, i.e. without a precipitating event. Risk factors for thrombosis include surgery, trauma, immobility, congestive heart failure, pregnancy including puerperium and oral contraceptive usage. The thrombotic risk is increased in patients who are homozygous for factor V Leiden and markedly increased in patients with combined defects.
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PMID:[Thrombophilic states]. 1035 55

Impaired left ventricular (LV) contractility is a major cause of cardiovascular death, especially congestive heart failure. The identification of susceptibility genes that contribute to impaired LV contractility may uncover mechanisms underlying LV contractile impairment and the development of congestive heart failure. The Hypertension Genetic Epidemiology Network (HyperGEN) collected echocardiographic measurements of myocardial contractility in a large biethnic sample of hypertensive siblings (390 blacks and 398 whites in 179 and 165 sibships, respectively). All participants expressed hypertension before age 60 years, and the mean age of siblings was 52 years in blacks and 61 years in whites. We adjusted myocardial contractility for gender, age, and age(2), and we calculated standardized residuals separately for men and women in both ethnic groups. We conducted multipoint variance components linkage analysis using GENEHUNTER2 and 387 anonymous markers (CHCL8 marker set). We found evidence for significant linkage to a microsatellite marker, D11S1993 (lod, 3.93 in blacks), approximately 54 cM from the tip of the short arm of chromosome 11, that accounted for 72% of the phenotypic variation in LV contractility. A chromosome 22 locus showed suggestive evidence for linkage (lod, 2.83 in whites and 1.15 in blacks). The chromosome 11 peak coincides with the region containing myosin-binding protein C. Mutations in this gene are linked to familial hypertrophic cardiomyopathy. Our results show strong evidence for linkage of a region of chromosome 11 with LV contractility in blacks and suggest that an important gene for impaired LV contractility is harbored in this region.
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PMID:Linkage of left ventricular contractility to chromosome 11 in humans: The HyperGEN Study. 1164 Dec 84

From the information presented in this article, it can be concluded that clinical suspicion of VTE should be increased in patients with a history of VTE, recent surgery, spinal cord injury, trauma, or malignancy. A variety of medical illnesses also increase the risk of venous thrombosis, including congestive heart failure, myocardial infarction, stroke with paresis, nephrotic syndrome, cigarette smoking, and obesity. Hypercoagulable states, such as antithrombin III deficiency, protein C deficiency, protein S deficiency, or factor V Leiden mutation should be considered in those patients who develop VTE in the absence of known risk factors. Additionally, the presence of vena caval filters does not exclude the possibility of PE or recurrent DVT. With a careful assessment of risk, physicians can hope to increase the diagnostic yield of VTE and decrease the significant morbidity and mortality of caused by this disease.
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PMID:Epidemiology of venous thromboembolic disease. 1176 74

Coumarin anticoagulants impair the biological activity of the vitamin K-dependent procoagulant and anticoagulant proteins. There are no reports that focus on the levels of these proteins in over-anticoagulated patients. Therefore, we determined the levels of factor II, factor VII, factor IX and factor X, protein C and protein S in 25 randomly selected over-anticoagulated patients (International Normalized Ratio >/= 6.0) and in 25 matched, therapeutically anticoagulated patients with an International Normalized Ratio within the therapeutic zone. Furthermore, to study a possible effect of the cause of over-anticoagulation, coagulant levels were compared between 16 over-anticoagulated patients with fever in the preceding 2 weeks and 24 over-anticoagulated patients with stable congestive heart failure. The pattern of procoagulant level reductions in the three groups of over-anticoagulated patients was largely the same as in therapeutically anticoagulated patients: factor X was the lowest and factor IX the highest. The difference was that, in over-anticoagulated patients, factor VII was relatively low among the procoagulant factors compared with therapeutically anticoagulated patients. Protein C was lower than protein S in over-anticoagulated patients with congestive heart failure, but was similar to protein S in the other study groups. In over-anticoagulated patients with fever, the vitamin K-dependent coagulation proteins except factor X were significantly lower than in over-anticoagulated patients with congestive heart failure, especially factor VII and protein S.
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PMID:Levels of vitamin K-dependent procoagulant and anticoagulant proteins in over-anticoagulated patients. 1244 13

Hypertrophic cardiomyopathy is typically inherited in an autosomal dominant pattern and has a variable age of onset and prognosis. Mutations in the myosin-binding protein C (MYBPC3) gene are one of the most frequent genetic causes of the disease. Patients with MYBPC3 mutations generally have a late onset and a relatively good prognosis. We report here more than 20 Old Order Amish children with severe neonatal hypertrophic cardiomyopathy caused by a novel homozygous splice site mutation in the MYBPC3 gene. The affected children typically presented with signs and symptoms of congestive heart failure during the first 3 weeks of life. Echocardiography revealed hypertrophic non-obstructive cardiomyopathy. These children had a life span averaging 3-4 months. All patients died from heart failure before 1 year of age unless they received a heart transplant. A genome-wide mapping study was performed in three patients. The disease related gene was localized to a 4.6 Mb region on chromosome 11p11.2-p11.12. This homozygous block contained MYBPC3, a previously identified cardiomyopathy related gene. We identified a novel homozygous mutation, c.3330 + 2T > G, in the splice-donor site of MYBPC3 intron 30. The mutation resulted in skipping of the 140-bp exon 30, which led to a frame shift and premature stop codon in exon 31 (p.Asp1064GlyfsX38). We have found a substantial incidence of this phenotype in Old Order Amish communities. It is also concerning that many unidentified heterozygous individuals who are at risk for development of hypertrophic cardiomyopathy do not receive proper medical attention in the communities.
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PMID:Homozygosity for a novel splice site mutation in the cardiac myosin-binding protein C gene causes severe neonatal hypertrophic cardiomyopathy. 1793 28

A comprehensive understanding of the pathogenesis of venous thrombosis is essential for identifying patients at increased risk and who may therefore benefit from more aggressive preventive and therapeutic measures. As for other pathologies, the pathogenesis of venous thromboembolism is multifactorial. All risk factors, either congenital or acquired, are relatively "innocent" when considered alone. However, when an individual is unlucky enough to inherit one or more abnormality, compounded in many cases by environmental hazards, that person may be propelled over a threshold that precipitates the development of thrombosis. An appropriate analogy is that where "the last drop makes the cup run over." A reinterpretation of the traditional Virchow's triad (abnormal vessel wall, abnormal blood flow, and abnormal blood constituents) was provided by Eberhard Mammen throughout his research, and this has contributed greatly to the understanding of the pathogenesis of this serious disorder. Mammen postulated immobility as the leading event, because it reduced blood flow as a result of decreased muscle contraction. The subsequent "stasis of flow" led to accumulation of blood within the intramuscular sinuses, especially of the calf, triggering hypercoagulability due to local accumulation of activated clotting factors and coagulation activation products and the simultaneous consumption of blood coagulation inhibitors. On Mammen's "hit list" nearly 20 years ago were included (among inherited abnormalities) decreased protein C, protein S, antithrombin III, plasminogen, and tissue plasminogen activator, and increased plasminogen activator inhibitor-1, whereas (among acquired predisposing conditions) surgery, trauma, previous thromboembolism, prolonged immobility and paralysis, malignancy, congestive heart failure, obesity, advanced age, pregnancy and puerperium, varicose veins, and oral contraceptives were also identified. Some two decades later, the situation has perhaps not changed so much, although studies continue to expand our knowledge of this topic, clarifying the relative contribution of each single risk factor in the pathogenesis of venous thrombosis.
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PMID:Pathogenesis of venous thromboembolism: when the cup runneth over. 1921 13

Acute fulminant myocarditis may present with cardiogenic shock refractory to inotropics and intra-aortic balloon pumping (IABP). Benefit of extracorporeal membrane oxygenation (ECMO) support has been established. The effectiveness of combination with ECMO or IABP and activated protein C (drotrecogin alpha; Xigris) in treatment has yet to be defined. Four patients presented with congestive heart failure 3-4 days after flu-like symptoms. Chest roentgenograms showed cardiomegaly and bilateral pulmonary infiltrates. Two-dimensional echocardiograms demonstrated severe myocardial dysfunction with left ventricular ejection fraction (LVEF), measured between 18.4% to 27% (mean, 19.5%). Three patients having been treated with the combination of ECMO or IABP and activated protein C were weaned. Follow-up LVEF measured were 39.9%, 43%, 53%, and 55%, respectively. However, 1 patient died a month later because of systemic lupus erythematosus and repeated infection. There were no neurologic sequelae in the 3 survivors. Serological test and myocardial biopsy for Parvovirus B19 was positive in 3 of 4 patients. Use of circulatory support and activated protein C is an effective alternative for acute life-threatening myocarditis.
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PMID:Successful use of extracorporeal membrane oxygenation and drotrecogin alpha in patients with acute life-threatening myocarditis. 1994 35

Genetic mutations account for a significant percentage of cardiomyopathies, which are a leading cause of congestive heart failure. In hypertrophic cardiomyopathy (HCM), cardiac output is limited by the thickened myocardium through impaired filling and outflow. Mutations in the genes encoding the thick filament components myosin heavy chain and myosin binding protein C (MYH7 and MYBPC3) together explain 75% of inherited HCMs, leading to the observation that HCM is a disease of the sarcomere. Many mutations are "private" or rare variants, often unique to families. In contrast, dilated cardiomyopathy (DCM) is far more genetically heterogeneous, with mutations in genes encoding cytoskeletal, nucleoskeletal, mitochondrial, and calcium-handling proteins. DCM is characterized by enlarged ventricular dimensions and impaired systolic and diastolic function. Private mutations account for most DCMs, with few hotspots or recurring mutations. More than 50 single genes are linked to inherited DCM, including many genes that also link to HCM. Relatively few clinical clues guide the diagnosis of inherited DCM, but emerging evidence supports the use of genetic testing to identify those patients at risk for faster disease progression, congestive heart failure, and arrhythmia.
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PMID:Genetic mutations and mechanisms in dilated cardiomyopathy. 2328 6


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