‘Survivor’ gene identified

Researchers have identified that some people have a genetic variation, which could make them twice as likely to survive severe infections such as pneumonia or MRSA.

A project studying the DNA of intensive care patients suffering with severe infections, found that patients who had a particular variation in their mitochondrial DNA (mtDNA) - which codes for the part of the cell that turns food into energy - had much higher survival rates than those without.

It has long been thought that there may be a connection between the workings of the mitochondria and how our bodies react to fight infections. This latest research confirms this theory.

The project, supervised by a Wellcome Trust Senior Clinical Fellow, identified ten major variants of mtDNA. Patients from each variant group were monitored and researchers found people with a particular variant - called haplogroup H - were more than twice as likely to survive to 6 months than people from any of the other groups.

There was no evidence to suggest that people from haplogroup H were any less likely to contract a severe infection in the first instance.

Prof Patrick Chinnery from the University of Newcastle, who lead the research with Dr Simon Baudouin, said:

“In identifying that some patients may be pre-disposed to survival or death on the intensive care unit is an important development and opens up new avenues to develop novel treatments. Those who seem to have less chance of survival may benefit from more aggressive clinical care.”

It is generally well known that mtDNA is only inherited from mother to child and has slowly evolved over tens of thousands of years resulting in the ten genetic variations seen today.

Prof Chinnery explained:

“Haplogroup H is the most recent genetic variation to evolve in people of European ancestry, but also the most common - around 40% have it. One explanation is that people with haplogroup H may be more likely to survive infection, meaning that other groups will slowly become less common.”

This project looked at a European population and the researchers now plan to conduct a research programme in other populations.

The findings are published in the Lancet, 17th December 2005.

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