Once-discarded blood from umbilical cords can be used to successfully treat children with Hurler’s syndrome, an often-fatal inherited disease caused by the accumulation of sugar-containing chemicals in the skull, face, brain and heart, doctors reported on Wednesday. Until now, a bone marrow transplant has been the best treatment for Hurler’s, an illness that affects one in 100,000 newborns and causes enlargement of the head and some tissues in the face, mental retardation, and hearing and vision problems.