Because racial groups have similar genetic characteristics, a large pool of black donors is needed to save blacks with diseased organs. In the US black patients constitute 27% of people on waiting lists, but only 12% of donors, according to the Organ Procurement and Transplantation Network. As a result, blacks wait an average of 18 months longer for a transplant than whites.

Many people involved with transplants blame the notorious Tuskegee experiments for blacks’ reluctance to become donors. Between the 1930s and the 1970s poor black men in Alabama were used as guinea pigs to see what would happen if their syphilis went untreated. “That kind of created a mistrust of health care professionals as far as it pertains to African-American people,” says Bobby Howard, a former American football player who retired from the gruelling sport in 1993 after his kidneys failed. He received a transplant eight months later and now promotes black organ donation. Many blacks also believe that white patients will be favoured over patients of other races — even though the computerised matching system does not select patients based on race, fame or wealth.