Obesity Genes

It seems that some of the people are intended to be skinny. These people actually have never known being fat, and they make being thin look easy. Others of them are in the opposite condition. It is a struggle to lose excess body weight, and being thin seems next to impossible. Some think it could be the genes have something to do with it. According to some, there are several types of genes that play a role in obesity. Defects in some of these genetic conditions cause certain syndromes to develop. Not everything is yet known about the genetics of obesity, but the knowledge is expanding.

Hypothalamus is the part of the brain that controls several functions of the body. One of these controls is the regulation of the sense of hunger. There is interplay between various internal chemical messengers and the hypothalamus. This interplay is medically known as the hypothalamic leptin-melanocortin system. The fat cells of the body make a signal called leptin. The more amounts of fat people have in the body, the more leptin is produced. It chemically binds to the leptin receptor in the hypothalamus. The hypothalamus part of the brain senses a minimal amount of leptin which tells the brain that the body has at least the required amount of fat to function.

Once the leptin receptor is activated, a protein called proopiomelanocortin or POMC is made. POMC protein is then cut into smaller parts by chemical enzymes. One of these internal enzymes is proenzyme convertase 1 (PC-1). One of the smaller proteins produced by the enzyme PC-1 is called alpha-MSH which binds another receptor in the hypothalamus called MC4R. Once MC4R receptor is turned on, it triggers some intracellular signals that end up telling the brain that the body is not that hungry.

A defect in the physiological construction or genetic construction for any of the signals, enzymes, and receptors mentioned above can lead to an increased appetite. The most common of these genetic mutations is a defect in MC4R. It is however not the most severe, and some of the people with a defective MC4R gene are still thin. Genetic mutations in other genes of the body cause a voracious appetite in very young children, and they are nearly destined to eat far more than their bodies will ever need.

In addition to becoming excessively overweight, associated problems can include like thyroid dysfunction, small ovaries and testicles, decreased immunity, and low functioning adrenal glands. These more severe ailments fortunately are rare with only a handful of known cases. There are effective treatments for a few diseases, like replacing leptin with shots. For other ailments like MC4R, there are to treatments. A few types of genes that aid in the development of the hypothalamus are also associated with obesity. Signals encodes by SIM1 gene that come from the MC4R receptor. SIM1 mutation example in young girl is they become obese and also tall. In addition to the conditions of the hypothalamus, the tropomysin-related kinase B (TrkB) receptor and the chemical signal called brain-derived neutrotrophic factor (BDNF) play roles in behavior, memory, and intellect.

• Matt Thompson
• 16/01/2009, 10:59 AM
• 0 Comments