OBESITY : As Genetic Disorder

Obesity:- A disorder involving excessive body fat that increases the risk of health problems.

We all are aware about the cause of obesity that mainly include our living style , our environment,  our food habbit, etc .These activities only contribute 60 % in causing obesity but the rest of 40 % is due to genetic disorder. 

However, recent studies suggest that genetics contribute in  obesity with the discovery of more than 50 genes that are strongly associated with obesity. While changes in the environment have significantly increased obesity rates over the last 20 years, the presence or absence of genetic factors protect us from or predispose us to obesity. “Genes may co-determine who becomes obese, but our environment determines how many become obese That’s why obesity prevention efforts must focus on changing our environment to make healthy choices easier choices, for all.

There are 2 ways of genetic mutation i.e. 1.single gene mutation and 2.multipe gene mutation 

■Single gene mutation {Monogenic Mutation }:-

It is the deletion or addition or any other changes that occur on single gene which further affect the coding of protein and led to malfunctioning which causes obesity. It is severe form of obesity that is mostly seen before 2 years of age . This mutation is included in leptin Receptor, proliferate opiomelanocortin and there are 2 gene on chromosome 18 close to melanocortin 4 Receptor gene which causes Monogenetic obesity. 

It includes syndrome like Prader willing and Barde Biede .


■Multiple gene mutation :-
It is due polymorphism in gene due to which multiple genes predipose to gain weight by controlling metabolism under dietary conditions. 

FTO { Fat Mass and Obesity Associated Gene}:-

It is gene that is present on chromosome 16 that is found in 43 % of the world's population that predipose to gain weight . This gene is dependent on our family inheritance. In this case , if both the parents are obese then the upcoming 80%  generation is obese and 10 % would be normal and 10 % less than normal weighted .

Effect of this gene are :- 1. Increases hunger level ,

2. Increases caloric intake, 3. Reduce satiety, 4. Reduce control over eating, 5. Increases tendency to be sedentary , 6. Increases tendency to store body fat .

• Obesogenic and leptogenic genes response to weight loss and it's management. 

• There are 41 sites in human genome that cause obesity under favourable conditions. 

• Scientists had found additional locci and quantitative trait locci for BMI .

• There are 30 genes on chromosome 12 that is responsible for BMI of our body .

• SNPS increases disease risk that mean obesity is accompanied mental retardation and reproductive anomalies.

Thrifty Gene Hypothesis Postulates :- 

It states that due to dietary scarcity during human evolution which had made population prone to obesity as during this period our body adapted to store fat as source of energy. 

• DNA methylation is a form of epigenetic modification that controls whether genes are turned on or off.

There are total 79 syndromes responsible for  obesity . Out Of the 79 syndromes, 43 have never been assigned a name, the review found. And scientists have fully figured out the underlying genetics of just 19 of the syndromes. For others, scientists have reported a partial understanding of the underlying genetics, according to the review. However, the researchers identified 22 syndromes for which scientists knew nothing about the gene or the chromosome associated with them.

Finally we can found that risk of obesity cannot be determined by only genotype  but also by gene - gene interaction. Rather than genetic reason,  overall cause of obesity is genetic environment interaction which interplay between genetic makeup and life experiences