Unique genes in Khoe-San people may lower risk of some pregnancy hazards

An unusual mutation in an immune system gene switches a receptor from one target molecule to another in Khoe-San people. It's the first known example of such a change, say researchers, and likely leads to safer pregnancies. The Khoe-San -- known for the unusual clicking sounds in their language -- harbor unusually high genetic diversity, about 10 times more among their 100,000 people than among modern Europeans.