A Dutch sperm donor who fathered 18 children is suffering from a rare hereditary degenerative brain disorder, a hospital said on Wednesday.

The man, whose sperm was used between 1989 and 1995, was not definitively diagnosed with cerebellar ataxia — which causes gradual shriveling of the cerebellum — until late 1998.
The children conceived from his sperm, now aged between seven and 13, have a 50 percent chance of inheriting the disease, according to the hospital, which agonized for three years before deciding to tell the parents involved.