What is MTHFR gene?
The MTHFR gene provides the complete instruction for the production of a metabolically important enzyme called 5,10-methylenetetrahydrofolate reductase. This enzyme catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate. Methyltetrahydrofolate is the biologically active form of folic acid, a very important vitamin in humans.
What are the Functions of the Methyltetrahydrofolate?
Methyltetrahydrofolate is needed in many biological reactions. The conversion of the amino acid homocysteine to methionine requires methyltetrahydrofolate. Methionine is among the many amino acids that build up protein.
Methyltetrahydrofolate is also important in gene silencing: a process of deactivating a particular gene so that it will not encode protein. Its methyl group (-CH3) attaches to a particular region in the DNA to deactivate it. Gene silencing is important in regulating the expression of a particular gene (e,g, oncogenes or cancer genes). If genes are not properly regulated, problems may occur like the development of diseases.
The methyl group of methyltetrahydrofolate is also required in the biosynthesis of nucleotides: the building blocks of DNA. Nucleotides are needed in DNA synthesis or the creation of new DNA strands. Rapidly dividing cells actively synthesize DNA for new cells formed; thus, they require a large amount of nucleotides.
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How MTHFR Mutation Causes Pregnancy Complications?
Methyltetrahydrofolate is not produced by the cells if there is a mutation in the MTHFR gene. MTHFR mutation results in the production of an altered/defective enzyme that cannot carry out its function efficiently or worse, the gene is completely inactivated that no enzyme is produced at all.
Inadequate amount of methylenetetrahydrofolate enzyme in the body due to MTHFR mutation could lead to homocysteinuria or the build up of amino acid homocysteine in the body. Homocysteinuria has a negative effect in the cardiovascular system and may cause pregnancy complications. According to a group of medical researchers, homocysteinuria is a risk factor in miscarriage because it triggers the formation of blood clots that obstruct the flow of blood towards the placenta.
MTHFR mutation also causes birth defects such as spina bifida (spine malformation) and anencephaly (malformation in the skull and brain). There is still no clear reason to explain the connection between the birth defects and MTHFR mutation. A research say that the birth defects occur because the gene called insulin-like growth factor is not properly methylated due to the inadequacy of methyltetrahydrofolate. Insulin-like growth factor gene is associated to the normal development of the nervous system.
MTHFR mutation also causes anemia to new born babies. This is because hematopoiesis or the production of new red blood cells is impaired. Stem cells of red blood cells cannot divide without new DNA synthesized caused by the absence of nucleotides.
Babies born with MTHFR mutation have low birth weight and small size. This is caused by intrauterine birth restriction due to MTHFR deficiency.
References
Genetics Home Center, National Institute of Health
Genetics Channel of Brighthub.com