Molecular screening for the G894T polymorphism of the endothelial nitric oxide synthase (eNOS) gene is performed to assess the risk of thrombosis in asymptomatic patients with a severe familial history or in patients who have already had a thrombotic thrombus.
Nitric oxide (NO) plays an important role in maintaining basic vascular tone. NO is a muscle relaxant for smooth muscles and inhibits platelet adhesion, activation, and aggregation. A deficiency in NO synthesis can be a predisposing factor for coronary artery disease, angina, and myocardial infarction. The endothelium-derived NO is synthesized from the amino acid L-arginine by the enzyme endothelial nitric oxide synthase (eNOS). This enzyme is encoded by the NOS3 gene located on chromosome 7. Substitution of Guanine by Thymine at nucleotide 894 of the NOS3 gene (G894T) results in the substitution at position 298 of the glutamic acid polypeptide chain by aspartic acid (Glu298Asp) which affects the stability of the eNOS enzyme. The enzyme isoform containing aspartic acid in the polypeptide chain (298Asp) breaks down faster than the enzyme that contains glutamic acid (298Glu). Numerous studies have identified the role of this polymorphism in causing atherosclerosis and thrombosis and as a risk factor for myocardial infarction. The G894T mutation of the NOS3 gene increases the risk of premature myocardial infarction. In addition, it was found that G894T polymorphism is a risk factor for the occurrence of preeclampsia in pregnancy.
Thrombophilia is an acquired or congenital disorder associated with thrombosis. The clinical appearance of an underlying thrombophilia mainly involves venous thromboembolism, which is manifested as deep vein thrombosis, pulmonary embolism, or superficial vein thrombosis. Other events associated with thrombophilia include recurrent miscarriages (pregnancy loss) and complications of pregnancy such as severe preeclampsia, placental abruption, and fetal intrauterine death. The demographic and environmental characteristics that contribute to the risk of venous thromboembolism in people predisposed to thrombophilia include old age, gender (more commonly in men), obesity, surgery, trauma, hospitalization for other diseases, malignant neoplasms, prolonged immobility (such as long plane trips), use of certain medications (such as contraceptives, estrogens, tamoxifen, and raloxifene and certain drugs used for the treatment of infertility).
Important Note
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
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