The New Yorker:

In 1976, my final year of medical school, I travelled abroad and spent several months working in the hematology clinic at Hadassah Hospital, in Jerusalem. Every day, I attended to children and teen-agers suffering from a blood disorder called beta thalassemia. They were easy to identify in the clinic waiting room. Their skin was a pale yellow, their skull and facial bones were distorted, and their abdomens bulged from an enlarged liver and spleen. Many were short of breath, with swollen legs and other signs of heart failure. Beta thalassemia, like its better-known cousin sickle-cell disease, is caused by a congenital defect in the globin protein, a key component of hemoglobin, the substance that allows our red blood cells to carry oxygen. Children who inherit only one copy of the faulty gene from their parents usually experience no symptoms; those who inherit two can suffer the full-blown effects of the disorder. Their red cells break down, resulting in severe anemia.

Beta thalassemia is one of the most common genetic diseases in the world, affecting an estimated three hundred thousand people, with another sixty thousand born every year. (Evolutionary biologists speculate that the gene has survived for so long because, like the sickle-cell mutation, it may confer resistance to malaria.) Beta thalassemia is prevalent in Africa, Asia, the Middle East, and, especially, the Mediterranean.

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