Un dono sgradito

Un articolo sul New York Times esamina il caso del donatore di sperma che negli Usa ha trasmesso una rara malattia genetica a cinque dei bambini concepiti usando il suo seme (Denise Grady, «As the Use of Donor Sperm Increases, Secrecy Can Be a Health Hazard», 6 giugno 2006).

Sperm donor No. F827 aced all the tests. He was healthy, and he said his parents and grandparents were, too. Under a microscope, his chromosomes looked perfect. He also turned out to be quite prolific: his deposits to a Michigan sperm bank during the 1990’s produced 11 children.
But he passed a serious gene defect to five of those children, a blood disease that leaves them at risk for leukemia and in need of daily shots of an expensive drug to prevent infections. They also have a 50-50 chance of passing the disease to their children.
Shouldn’t the sperm bank have detected the bad gene and rejected the donor?
Geneticists say no, because the disease is extremely rare and sperm banks cannot be expected to test for every possible mutation.
But that bit of uncertainty raises other questions. Should any donor produce so many children, when they will be scattered far and wide, making it harder to recognize a pattern of illness than it would be if they all lived under one roof? It’s also worth asking whether damage could be limited by requiring sperm banks to keep track of donors’ babies so that if one or more got sick, other families who had used the same donor could be warned, sale of the sperm stopped and the donor notified.