There can be many mutations in the MTHFR gene, which lead to changes in the body's production of the methylenetetrahydrofolate reductase enzyme, also known as MTHFR, according to Genetics Home Reference. MTHFR mutations have been associated with many disorders including homocystinuria, anencephaly and spina bifida.
Mutations in the MTHFR gene cause homocystinuria, a disorder in which amino acids are not processed properly, notes Genetics Home Reference. There are at least 40 mutations of the MTHFR gene documented in people with homocystinuria, which impair the function of the MTHFR enzyme or cause it to turn off. When the MTHFR enzyme is impaired, the body has altered levels of amino acids, which causes various health problems.
Mutations in the MTHFR gene are also associated with neural tube defects such as anencephaly and spina bifida, explains Genetics Home Reference. It is thought that because a shortage of folate is a risk factor for neural tube defects, and that the mutations change the ability of the MTHFR enzyme to process folate, people with the mutations are more at risk for the disorders. However, most people who have mutations in the MTHFR gene, and their children, do not have neural tube defects.
People with mutations in the MTHFR gene also have an increased risk for other disorders such as heart disease, stroke, hypertension and certain types of cancers, states Genetics Home Reference. It is not known how the mutations cause these conditions, because many unknown genetic and environmental factors determine the risk of developing them.