Genetics of Type 2 Diabetes-A Review Article.


Genetics of Type 2 Diabetes-A Review Article: Type 2 diabetes (T2D) as a complex disease is the result of genetically heterogeneous factors and environmental issues interaction. Linkage and small-scale candidate gene studies were successful in identification of genetic susceptibilities of monogenic form of diseases. However, they were largely unsuccessful while applying to the more common forms of disease. By designing Genome Wide Association studies (GWAs), the new windows open to genetic approaches. So far, around 153 variant were discovered for T2D and missing rare variants are waiting to be discovered. The new findings are beneficial to explain molecular signaling and pathways responsible for pathophysiology of T2D, which offered opportunities for the development of novel therapeutic and preventive tactics. The GWAs findings need to be confirmed in on going researches. In this review, we address, genetic susceptibilities related to T2D since 2007. Also challenge advantages and disadvantages of GWAs and discuss about the next confirmatory approaches need to be done.

Introduction; Genetics of Type 2 Diabetes

Type 2 diabetes (T2D) is a worldwide concern. Based on International Diabetes Federation, 285 million adults aged 20–79 years suffered from diabetes in 2010. About 60% of them located in Asia. Almost 80% of people with diabetes live in developing countries. Around 95% of diabeti patients suffer from T2D (1-3).Worryingly, new findings show decrease in the onset age of T2D. The disease is more frequently reported among young Africans and Pima Indians (4).
T2D in Asia differs from the other world regions; since it has developed in younger age group, and in people with much lower bodymass index (BMI) (5).

This review will highlight the genetic discoveries of T2D. T2D and Metabolic traits T2D is a complex metabolic disease (6). Complex disease like T2D and cancers are the results of both environmental and genetic risk factors and also intrauterine environment. However they do not follow a Mendelian pattern of inheritance and cannot be described by a single gene disorder, so this hypothesis “common illnesses common variants” help to understanding mechanisms of these kind of diseases (7,8). Environmental factors are largely responsible for T2D. Decreased physical activity and increased fat consumption lead to
augmentation of nutrient storage. This kind of Long-term fatty diet is associated not only with the progress of obesity but also with reductions in insulin release (9).

Environmental factors will be bolded while the genetic abnormalities already exist. Moreover, changes in the amounts of dietary carbohydrate and fat can affect both insulin sensitivity and insulin release in three days, while obesity does not exist (10). Other environmental condition that should be considered is in utero environment.

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