Gene is Africans shuts the body's immune system

a gene present in about 20 per cent of Africans can shut down the body's immune system, leaving it vulnerable to lethal infections, claims a study by scientists led by Maya Saleh of Canada's McGill University Health Centre.

The study was based on blood samples taken from about 1,000 African people living in Montreal. The gene codes for a protein called caspase-12. Saleh and colleagues found that caspase-12 blocks the body's protective inflammatory response by stopping the action of a useful enzyme called caspase-1. The findings were published in Nature (Vol 440, No 7087, April 20, 2006).

All other populations, except Africans, lost this gene some 60,000 years back. The team suggests this gene might have once guarded against parasites and auto-immune disorders. But now, the gene makes the body prone to life-threatening infections and sepsis (septic shock). The presence of this gene increases mortality rate by three times. But following the discovery, patients with sepsis can be screened for this gene and then given appropriate treatment to boost their immune systems.