Cancer risk stomach cancer favored by genes

Genetic predisposition affects carcinogenesis

01/14/2014

The human body is full of bacteria. Whether in the mouth, on the hands or in the intestines. Without the tiny little organisms, human survival would certainly not be possible. Over time, the human body has adapted and adjusted to the dangers.

Not only the genes of humans have changed in the course of evolution, also the pathogens of various diseases adapted to the changes of the human body. A connection between the evolution of the genome in humans and bacteria could apparently be detected and with it the susceptibility to infection and its strength.

This is what US researcher Babara Schneider and her team want to do in studies of people who use the so-called „Helicobacter pylori“ -Bacterium (HP). The researchers published their results in the journal "PNAS". This pathogen is significantly involved in the development of gastric cancer, inflammation of the gastric mucus and gastric ulcer and is found on and within the mucous layer of the stomach.

People around the world are carrying it, but only a fraction of those infected have serious complaints. For their investigations, the scientists then examined the genetic material of people from two areas in Colombia. The researchers were particularly interested in the spread and variants of the HP bacterium, because in Central America gastric cancer is much more common in mountainous areas than in coastal regions. Here, as part of the colonization of the continent by the predominantly Spanish occupiers developed a European variant of the bacterium.

The researchers were able to prove that the strains of the pathogen have adapted in the course of evolution to different degrees to the human organism on the different continents. For example, people of Indian ancestry have found that the African offshoot of the HP bacterium is more likely to cause precursors to cancer than people of African descent. This fact leads the scientists to conclude that the African variant has evolved with the African population and thereby lost in aggressiveness. By contrast, bacteria dominated by European shares would not have developed with humans and would therefore be more aggressive. (Fr)