In a new genetic study led by Swedish scientists, the indigenous peoples of the Argentinean part of the Andes have been found to carry a gene that accelerates the metabolism of arsenic.
High levels of arsenic in drinking water are linked to a range of health problems, e.g. an increased risk of cancer, heart disease or diabetes.
“We know that many bacteria and plants have genes that increase resistance to arsenic, a highly toxic substance that is found in soil and water in many parts of the world. There has been no previous research on whether the people in these regions also have protective genes against arsenic”, said Dr Karin Broberg of Lund University in Sweden, senior author of the study published in the journal Environmental Health Perspectives.
In the Andes, people have lived with drinking water containing arsenic for thousands of years. Even 7,000-year-old mummies from northern Chile have been found to have high levels of arsenic in their hair and internal organs.
“We found that the people up in the mountains in Argentina had unusually efficient metabolism of arsenic. This meant that the toxin left the body rapidly and less toxically instead of accumulating in tissue,” Dr Broberg said.
The researchers have studied the genes of residents of the small town San Antonio de los Cobres in Argentina, and compared them with those of the indigenous peoples from Peru, Colombia and Mexico. Over two thirds of the Argentinean villagers were found to possess the protective variant of a gene known as AS3MT – the major arsenic-metabolizing gene – that accelerates the metabolism of arsenic.
“It is known that many of the genes that control the metabolism of poisons in the body have a large number of variants that occur with varying prevalence around the world. There may therefore be different adaptations among different populations, depending on what toxins they are exposed to in the local environment,” Dr Broberg said.
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Bibliographic information: Carina M. Schlebusch et al. Possible Positive Selection for an Arsenic-Protective Haplotype in Humans. Environmental Health Perspectives, published online October 16, 2012; doi: 10.1289/ehp.1205504
