A purely Greenlandic cause of diabetes

"Diabetes gene" found in Greenlanders

<url>Geneticists have accomplished a real feat.

Taking a blood test from 2,575 residents of Greenland (10 percent of the population) scattered over a huge area of the island (more than the whole of Western Europe), they identified a genetic mutation that causes type II diabetes in Greenlanders. The results of the study are presented in the latest issue of the journal Nature (A common Greenlandic TBC1D4 variant confers muscle insulin resistance and type 2 diabetes – VM).

An international team of scientists found that this mutation of the TBC1D4 gene raises the level of glucose and insulin in the blood two hours after eating (to simulate eating, patients were given an oral glucose solution), and also increases the risk of diabetes. This variant of the gene is found only in Greenlanders and is responsible for 15 percent of all cases of diseases on the island.

It was not easy to take a blood test from 10 percent of the island's population – everything turned out only thanks to the influx of volunteers. It was also difficult to analyze the data: many respondents turned out to be close relatives.

A picture from the press release of the University of Copenhagen
Scientists break the genetic code for diabetes in Greenland – VM.

But the technology of DNA microchips helped to quickly "scan" the collected samples for 250,000 mutations associated with metabolic diseases. Scientists' attention was attracted by a certain variant of the TBC1D4 gene, which controls glucose uptake in muscle cells. In carriers of this mutation, muscles do not absorb glucose well, so after eating, for example, the blood sugar level rises sharply. There is no such mutation in the genome of Europeans, but 23 percent of Greenlanders are endowed with it. 60 percent of individuals over the age of 40 who inherited TBC1D4 from both parents have type 2 diabetes.

Studies of genetic associations are usually carried out on large, demographically mixed populations, but the new work suggests that they bring excellent results when working with small isolated groups. In general, the mechanisms of action of pathogenic genes in such cases are much easier to identify.

The authors of the article also ventured to assume that this mutation appeared during natural selection as an adaptation to the traditional diet of Greenlandic fishermen and seal hunters (rich in proteins and fats, but practically devoid of carbohydrates), and it became "harmful" as a result of the transition to a more Europeanized type of diet.

Portal "Eternal youth" http://vechnayamolodost.ru19.06.2014