Non-Coding DNA Implicated in Type 2 Diabetes

Variations in non-coding sections of the genome might be important contributors to type 2 diabetes risk, according to a new study. DNA sequences that do not encode proteins were once dismissed as "junk DNA," but scientists are increasingly discovering that some such regions are important for controlling which genes are switched on. The new study, published online on January 12, 2014 in Nature Genetics, is one of the first to show how such regions, called regulatory elements, can influence people's risk of disease. Type 2 diabetes affects over 300 million people worldwide. Genetic factors have long been known to have an important role in determining a person's risk of type 2 diabetes, alongside other factors such as body weight, diet, and age. Many studies have identified regions of the genome where variations are linked to diabetes risk, but the function of many of these regions is unknown, making it difficult for scientists to glean insights into how and why the disease develops. Only approximately two per cent of the genome is made up of genes: the sequences that contain code for making proteins. Most of the remainder is shrouded in mystery. "Non-coding DNA, or junk DNA as it is sometimes known, is the dark matter of the genome. We're only just beginning to unravel what it does," said leading author Professor Jorge Ferrer, a Wellcome Trust Senior Investigator from the Department of Medicine at Imperial College London. In the new study, scientists mapped the regulatory elements that orchestrate gene activity in the cells of the pancreas that produce insulin. In type 2 diabetes, the tissues become less responsive to insulin, resulting in blood sugar levels being too high.
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