Maria is Referred to a Dietitian
The dietitian appreciated that Maria’s MTHFR result has implications for Maria’s nutritional needs, as well as for her risk to have another pregnancy affected with a neural tube defect. The dietitian also pointed out that although more research needs to be done, Maria's low folate status and TT genotype could have potential implications for her risk for common chronic diseases such as heart disease and cancer later in life.
The dietitian took time to explain the MTHFR genetic test to Maria, and what her results indicate about her risk. Maria stated that she wished that the researchers had told her more about the genetic test when they offered it to her as part of the research protocol.
Patient Education and Informed Consent
Providing people with information about their genetic make-up through the use of genetic tests is often considered to be different than providing other types of medical information, such as a result from a cholesterol test. In this case, the research genetic testing done on Maria is predisposition testing, because the risk for the eventual development of symptoms is increased but not certain when the gene mutation is present. The onset of disease is influenced by environmental factors. Genetic test results may affect patients differently than other laboratory tests because the results cannot be changed, and because genetic information is inherited, it has implications for patients’ relatives as well.
Making decisions about genetic testing requires education to allow the patient to understand the implications of the information. Some people may not want to know about their genetic make-up because it cannot be changed and may not lead to a different treatment or management approach. Others may want the information, but have not considered the implications of that information for their children or other relatives or for their own treatment. It is important that healthcare providers discuss with patients the goal of testing, implications of the possible results for the individual being tested, and the implications of results to relatives. In Maria’s case, the researchers did not provide sufficient education about the purpose, benefits, and limitations of testing for variants in the MTHFR gene.
One polymorphism, multiple effects in the body
Maria and the dietitian discussed what is known about the implications of MTHFR on risk for several common disorders, and how it may be possible to reduce risk through dietary interventions. Maria was surprised that a change in one gene could affect her susceptibility to several different disorders.
It is estimated that humans have about 25,000 genes, which is a relatively small number, considering how complex we are. The complexity is explained by genes having multiple functions throughout the body, and in some cases by those functions being directed by environmental and biological cues. This means that a change in one gene will potentially affect multiple body systems and in different ways. For example, having the TT genotype for MTHFR at nucleotide 677 increases a woman’s risk of having a child with a NTD in the context of low folate status. Below are some other examples of how MTHFR has been associated with health outcomes.
>>Learn more about the impact of the MTHFR 677 C→T polymorphism on homocysteine levels and folate metabolism.