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Gene therapy shows promise in brain disease

Children born with a rare genetic brain disorder that causes severe atrophy and often leads to death within three years are still alive 7 to 10 years after being treated with an experimental gene therapy, a study showed.

The study, published yesterday in the journal Science Translational Medicine, described the procedure of inserting a virus containing healthy genes into the brain via holes drilled into the skull. Thirteen children, including a 3-month-old whose disorder was diagnosed in the womb, were treated in the Cell and Gene Therapy Center at the University of Medicine and Dentistry of New Jersey, Stratford, N.J.

The 13 are among only about 600 people in the world with the disorder, called Canavan disease, a nerve-cell destroying condition marked by brain atrophy, seizures, vision loss, physical disability and ultimately death. There is no treatment or cure.

"We were able to change a terminal diagnosis in these patients into a nonfatal diagnosis," study author Paola Leone, an associate professor of cell biology at the university, said.

The study, which began in 2001, was the first approved by U.S. regulators using an adeno-associated virus, a type of virus used in gene therapy because of its benign effects on humans.

Today's oldest patient in the clinical trial is 18 years. She "has major cognitive abnormalities, but she's not in a vegetative state," Leone said. She indicates "yes" by blinking, "no" by opening her mouth.

Canavan disease is caused by recessive mutations. When two of them occur, the body can't make an enzyme used to break down a compound called NAA in nerve cells in the brain. The buildup in the brain, along with unusual patterns of the insulation called myelin that lines nerve cells, are characteristic of the illness.