What Are the Genetic Causes of Obesity?

What Are the Genetic Causes of Obesity?

Overweight or obesity is defined as abnormal (excessive) fat accumulation in the body. If the value calculated according to height and weight (Body Mass Index: BMI) is over 25, the person is considered overweight, and if it is over 30, the person is considered obese. Obesity rates in adults and children are gradually increasing and have reached the level of a global epidemic. The World Health Organization reported that 1.9 billion people were overweight and 650 million were obese in 2016. More than 4 million people die each year from problems caused by being overweight or obese.

Causes of Obesity

    Nutrition habits
  • Physical activity
  • Psychological factors: Stress, poor sleep
  • Medications
  • Diseases: Hypothyroidism (underactive goiter gland), high insulin resistance, Polycystic ovary syndrome
  • Genetics

Obesity and Genetics

The main cause of obesity is the energy imbalance between calories consumed and calories expended. Genetic factors may be effective, especially if the amount of calories taken (despite normal or low) cannot be converted into energy in the body. Many different mechanisms (pathways) in the body work in a healthy way under the influence of genes and epigenetic factors in the conversion of the nutrients taken into energy. Defects in any of the genes or epigenetic factors responsible for the functioning of these pathways constitute the genetic causes of obesity.

Single Gene Related (Monogenic) Causes

  • Genetic mutations (errors) occurring in one of the genes involved in energy metabolism.
  • LEP, LEPR, POMC, MC4R, SIM1, etc..

Syndromic Causes

  • Obesity may accompany growth retardation or congenital defects of other systems.
  • Bardet Biedl Syndrome, Prader Willi Syndrome, Down Syndrome, etc..

Polygenic causes:

  • Mutations that occur in more than one gene involved in energy metabolism.

Epigenetic Causes

  • It is the heritable changes that occur in the chemical structure of DNA without mutation in its sequence.
  • Familial predispositions, Ethnic groups

Genetic Approach

Many causes of overweight and obesity are preventable and reversible. However, the environmental contribution is limited in some types of extreme and early-onset obesity. In such cases, genetic causes should be investigated. Genetic tests can provide important benefits in terms of diagnosing patients correctly and guiding treatment.