Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0018799 (heart disease)
 34,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cardiac arrhythmias cause more than 300,000 sudden deaths each year in the USA alone. Long QT syndrome (LQT) is a cardiac disorder that causes sudden death from ventricular tachyarrhythmias, specifically torsade de pointes. Four LQT genes have been identified: KVLQT1 (LQT1) on chromosome 11p15.5, HERG (LQT2) on chromosome 7q35-36, SCN5A (LQT3) on chromosome 3p21-24, and MinK (LQT5) on chromosome 21q22. SCN5A encodes the cardiac sodium channel, and LQT-causing mutations in SCN5A lead to the generation of a late phase of inactivation-resistant whole-cell inward currents. Mexiletine, a sodium channel blocker, is effective in shortening the QT interval corrected for heart rate (QTc) of patients with SCN5A mutations. HERG encodes the cardiac I(Kr) potassium channel. Mutations in HERG act by a dominant-negative mechanism or by a loss-of-function mechanism. Raising the serum potassium concentration can increase outward HERG potassium current and is effective in shortening the QTc of patients with HERG mutations. KVLQT1 is a cardiac potassium channel protein that interacts with another small potassium channel MinK to form the cardiac I(Ks) potassium channel. Like HERG mutations, mutations in KVLQT1 and MinK can act by a dominant-negative mechanism or a loss-of-function mechanism. An effective treatment for LQT patients with KVLQT1 or MinK mutations is expected to be developed based on the functional characterization of the I(Ks) potassium channel. Genetic testing is now available for some patients with LQT.
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PMID:Genetics, molecular mechanisms and management of long QT syndrome. 955 90

IsK, a slowly activating delayed rectifier K+ current through channels formed by the assembly of two channel proteins KvLQT1 and MinK, modulates the repolarization of cardiac action potentials. Mutations that map to the KvLQT1 and minK genes account for more than 50% of an inherited cardiac disorder, the Long QT syndrome (Splawski, I., Tristani-Firouzi, M., Lehmann, M. H., Sanguinetti, M. C., and Keating, M. T. (1997) Nat. Genet. 17, 338-340). Despite the importance of these channels to human cardiac function, the molecular basis of their uniquely slow gating properties as well as the stoichiometry and interaction sites of these two subunits are still unclear. We have constructed several fusion channel proteins to begin investigating the stoichiometry of these two subunits and the role of voltage-dependent subunit assembly in channel gating. Functional properties of these constructs were measured using whole cell patch clamp recordings of transiently transfected Chinese hamster ovary cells. The constructs we tested are as follows: MK24 (C terminus of MinK linked to N terminus of KvLQT1); KK40 (a tandem homodimer of KvLQT1); and MKK44 (C terminus of MinK linked to N terminus of KK40). In control experiments (no DNA, control DNA, or only MinK), no time-dependent K+ current was observed. Expression of KvLQT1 or KK40 produced currents that activate and inactivate in a voltage-dependent manner as reported by others for KvLQT1. In contrast, expression of MK24 and MKK44 elicited current with activation kinetics and voltage dependence very similar to native IsK and identical to currents expressed by cells co-transfected with independent MinK and KvLQT1 cDNA. Expression of MK24 plus additional MinK significantly slows current kinetics. Our data raise the possibility 1) of multiple MinK/KvLQT1 stoichiometries and 2) indicate that uniquely slow kinetics of IsK channels is due to voltage-dependent conformational changes of the channel protein and not to assembly of channel subunits.
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PMID:MinK-KvLQT1 fusion proteins, evidence for multiple stoichiometries of the assembled IsK channel. 985 64

Interactions of MinK and e-NOS Gene Polymorphisms Appear to Be Inconsistent Predictors of Atrial Fibrillation Propensity, but Long Alleles of ESR1 Promoter TA Repeat May Be a Promising Marker. We analyzed minK, e-NOS and ESR1 gene polymorphisms in 40 patients with atrial fibrillation (AF) without major structural heart disease compared to 35 healthy controls. A missense polymorphism in the minK gene with A/G substitution at nucleotide 112 causing serine (S) to glycine (G) change, 786 T/C polymorphism in the 5' flanking region of e-NOS gene and TA polymorphism in the regulatory region of estrogen receptor ESR1 gene with long (> or = 19 TA repeats) and short alleles were examined. Only a slight increase in minK G allele frequency, but with marked excess in AG/TT combination of minK and e-NOS polymorphisms was found in the AF group. The interpretation remains tentative due to small groups precluding statistical significance of differences, possible lab flaws and inconsistencies with earlier data. However, ESR1 long allele homozygotes were strikingly more frequent in the AF than in control group, reaching statistical significance surprisingly in males (p < 0.02). Functional activity of estrogen receptors may be more critical in males than in females with abundance of circulating estrogen. Contrasting the intricate complexity of genetic polymorphisms influencing cardiac rhythm with our modest research, we would limit the conclusion to the plea for further research of ESR1 role in AF.
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PMID:Interactions of MinK and e-NOS gene polymorphisms appear to be inconsistent predictors of atrial fibrillation propensity, but long alleles of ESR1 promoter TA repeat may be a promising marker. 1986 Jan 28