A promising technique could make blood types mutually compatible

EVERYONE HASOA B AB O O a blood group, defined by the characteristic chains of sugar molecules, or antigens, that protrude from their red blood cells like spikes on a hedgehog’s back. Not all these groups are created equal. In the roughly 50% of people with type , the sugars are harmless, allowing their blood to be transfused into any needy body. In those with and blood groups, however, the antigens can trigger harmful immune reactions in someone with a different group. Those with blood, who have both types of antigen, can only donate blood to one another.Supplies of are therefore in very high demand. If other groups could be transformed to , the supply of universal donors could be instantly doubled. Now researchers reckon they might have found a way to do it, thanks to a new mix of enzymes found inside gut bacteria.