New gene therapies promise a cure for sickle cell disease but experts say they are out of reach in places that need them the most. Vast inequities cut much of the world off from gene therapy in general, a whole new class of treatments that aims to eradicate inherited diseases by changing DNA. Such therapies are among the most expensive in the world. They also can be extremely complex to give patients, requiring specialized equipment and long hospital stays. Many parts of the developing world simply don’t have the resources. The sickle cell treatments were recently approved in Britain, Bahrain and the U.S.