Doctors test gene fix for devastating childhood brain disease

This early-stage trial tested a gene therapy for metachromatic leukodystrophy (MLD), a rare and severe genetic disorder that damages the brain and nervous system. Researchers collected blood stem cells from 20 pre-symptomatic or early-symptomatic children with MLD, used a modified virus to insert a working copy of the faulty gene into those cells, and then returned the cells to the patients. The main goals were to see if the treatment was safe and if it could increase the missing enzyme activity and potentially slow the disease's progression.