A build-up of phenylalanine is toxic to the central nervous system. When a very strict diet is begun early and well maintained, children with the disease can expect normal development and are able to have a normal life span. Dietary restrictions are crucial to successful management of the disease. The protein-free diet that needs to be followed by these patients excludes all meat, fish, poultry, nuts and dairy products. Researchers believe PKU is an excellent disease to target with gene therapy as it is caused by a single gene mutation.
Gene therapy involves delivering corrective genes to the cells of selected tissues.
They then injected the modified virus into male mice that had a defect similar to that of PKU patients. In the mice that received the virus, phenylalanine levels were significantly reduced to near normal levels. We know what the effective dose is, and there don't seem to be any adverse effects related to the treatment. The therapy did not prove to be successful when studying female mice, say researchers. They are continuing to study options for treatment in females.