Friday, April 28, 2006

Gene linked to lethal infections in African populations

CBC News:

A team of researchers, including a scientist in Montreal, has discovered how a gene is linked to lethal infections found in about 20 per cent of people of African descent.

Maya Saleh, a medical scientist at the McGill University Health Centre, analyzed blood donations from about 1,000 members of Montreal's black community.

One in five people of African descent carry the gene coding for the protein caspase-12. All other ethnicities lost the variant about 60,000 years ago.

Scientists don't know why African populations retained the protein, although Saleh told CBC News on Tuesday that it's thought that it may have once had a protective role for fighting autoimmune diseases or parasites such as malaria.

Saleh and colleagues in California found the gene protein blocks the body's inflammatory response to certain dangerous bacteria, such as those that cause sepsis, a body-wide infection.

The genetic variation can be particularly dangerous for people of African descent who are admitted to intensive care, where sepsis is most often contracted.

"We found the presence of this variant increases mortality rate by three-fold," Saleh said. "So we think it's very serious."

Black people who come down with sepsis should be genetically tested, she advised.

"Definitely, if we have African patients with sepsis in the ICU one of the first thing to do, in my mind, is actually to screen for this variant, and if its present, the first treatment would be to boost the immune system."

Elizabeth-Ann Williams, who volunteered to give blood for the research project, said she hopes the findings will help her community.

"With the knowledge that the medical staff has, then action can be taken to protect us with the coverage of antibiotics and so on," Williams said. "It would not be a mystery as to why we are not responding during treatment."

The next step for the team is to try to find a drug that will block the action of the gene variant.

The study, which appeared in the April 20 issue of the journal Nature, was funded by the Canadian Institutes for Health Research.

Method by which Caspase-12 shuts down the body's immune system discovered

Caspase-12 antagonists could potentially be useful in the treatment of sepsis and other inflammatory and immune disorders

Lack of caspase-12 enzyme dramatically increases resistance to sepsis

Caspase-12 gene that shuts down immune system is found in 20% of people of African descent

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