Molecular screening for the C677T mutation of the 5,10-methyltetrahydrofolate reductase (MTHFR) gene is performed to assess the risk of thrombosis in asymptomatic patients with a severe familial history or in patients who have already had tumors.
The 5,10-methyltetrahydrofolate reductase (MTHFR) deficiency is an inherited autosomal recessive disorder and is the most common genetic defect to folic acid metabolism. This polymorphism of the MTHFR gene is the result of a mutation in nucleotide 677, in which Cytosine (C) is replaced by Thymine (T). This mutation results in the replacement of the amino acid Alanine (Ala) at position 677 of the polypeptide chain with Valine (Val). Homozygosity or heterozygosity for this mutation of the MTHFR gene results in decreased enzyme activity and therefore reduced synthesis of 5-methyl-tetrahydrofolic acid, the primary donor of methyl radicals during homocysteine conversion which eventually causes hyperhomocysteinemia (increased homocysteine in the blood), homocystinuria (increased homocysteine in the urine), and hypomethioninemia (decreased methionine in the blood). Elevated plasma homocysteine levels are a risk factor for venous and arterial thrombosis as well as for cardiovascular and neurological diseases. Hyperhomocysteinemia has been reported in women who have miscarriages, and MTHFR gene mutations may be a risk factor for unexplained miscarriages. The underlying diseases of the mother's vessels increase the risk of preeclampsia, one of the most common and serious complications of pregnancy. Mutation of the MTHFR gene increases the risk associated with factor V Leiden mutation for deep vein thrombosis.
There are individuals with two copies of the normal MTHFR gene (677CC, normal homozygotes), homozygotes with two mutant MTHFR genes (677TT) and moderate lack of MTHFR enzyme activity, and heterozygotes MTHFR (677CT) with the almost normal activity of the enzyme as the production of the enzyme from the normal gene is enough to almost cover the reduced activity of the enzyme derived from the mutant gene.
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).
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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