Did you see last Sunday’s report of the 11-year-old 200kg girl who went on Fantastic? Obesity is a disease of caloric imbalance that results from excess calories ingested above body energy expenditure, and it is commonly recognized that diet structure and physical inactivity are essential factors for the progress of obesity.
However, some individuals still face the problem of obesity, although they live a healthy life. Except for the combination of diseases, both lifestyle and genetic characteristics also show contributing factors for the development of the condition, being the melanotaretine-4 receptor gene (MC4R), one of the hereditary factors of obesity and already portrayed in literatura.
This is the case of the 11-year-old girl who reached 200 kilos and underwent bariatric surgery after a decision by the Court, based on the biological explanation of genetic character. In this child, a mutation was identified in the MC4R gene, receptor of the melanoretine protein 4, which acts directly under the hypothalamus, responsible for maintaining the metabolism and production of hormones (leptin and insulin) in homeotase, as well as transmitting to the brain signs of hunger and satiety. Thus, this observed genetic condition deregulates important functions associated with food intake control, energy balance and weight control.
Gene MC4R: Melanocortina Receptor 4
Responsible for encoding the melanoretine 4 receptor that is present in the membrane of the hypothalamus cells, is a part of the brain responsible for regulating hunger and satiety. Therefore, mutations associated with these proteins generate variations in the food supply control pathways, culminating in the development of potentially severe and early obesity, as observed in eleven-year-old children.
Possible mutations observed in the MC4R gene are C/C or C/T, which are associated with increased risk of obesity and eating disorders, such as binge eating, usually the most caloric and feeling of hunger more intense and/or more frequent. Another possible variation is T/T, however, it is shown to be uninfluenced in the tables mentioned above.
Why obesity?
Obesity is a major health problem worldwide, according to the World Health Organization, more than 400 million people worldwide are obese. In addition, several evidences have established that obesity is associated with increased risk of hypertension, type 2 diabetes and cardiovascular disease. Recently, the identification of genetic factors that contribute to obesity are themes that gain relevance.
Currently, it is known that the polymorphism RS17782313 and RS12970134 close to the MC4R gene are factors for increased risk of obesity, in addition to the consequences mentioned above regarding hormonal regulation and metabolism, there is solid evidence that mutations in MC4R can also modify the regulatory system of the individual’s energy expenditure.
In this way, the presence of the risk polymorphism of the MC4R gene impacts the body from childhood, influencing the increase in body mass index and greater difficulty in losing weight, it may be necessary in some cases more incisive interventions such as the indication of bariatric surgery, since the patient tends not to have good responsiveness in the face of “more common” medications and caloric deficit.
Clinical practice
With clinical practice, nutritionists can use as a screening strategy for mutations in the MC4R gene the request for genetic tests, which may contribute to greater assertiveness in later conducts.
Bibliographic references
Reading Suggestion: Obesity
and Female Infertility: Potential Mediators of the Impact of Obesity
Watch the video on the Science Play platform –
Obesity and its Implications
Article: Xi B, Chandak GR, Shen Y, Wang Q, Zhou D. Association between common polymorphism near the MC4R gene and obesity risk: a systematic review and meta-analysis.
PLoS One. 2012;7(9):e45731. doi: 10.1371/journal.pone.0045731. Epub 2012 Sep 25. PMID: 23049848; PMCID: PMC3458070.
