Getting Healing Genes To The Right Organ

A CRITICAL GOAL OF GENE THERAPY is to devise a way to inject a corrective gene into the bloodstream. The gene would then home in on the right organ and go to work, producing a protein to treat or cure a disease. It's a great theory, but getting it to work has been difficult. Now, scientists are nearing their genetic goal in an

inherited disease called ornithine transcarbamylase (OTC) deficiency.

About 1 in 30,000 children are born with the condition, an enzyme deficiency that leaves them unable to convert toxic ammonia into urea, which can lead to coma and death. A team at Philadelphia's Children's Seashore House and the University of Pennsylvania, led by Dr. Mark L. Batshaw, has been working on a method to deliver the gene for the missing enzyme. By periodically injecting the tail veins of mice with a modified virus that carries the gene to the liver, the researchers say they have been able to cure the animals of the disease. Most exciting, they say, the gene therapy continued to work throughout the 10-month lifespan of the mouse, as opposed to just a few weeks. "We've been able to keep the animals metabolically stable for their lifetimes," says Batshaw.

The team has also begun the first human trials of a gene therapy treatment with healthy volunteers, looking for evidence that the added gene is speeding conversion of ammonia to urea. The trials are still in an early stage, but thus far, the treatments show "encouraging results" and no toxic effects, says Batshaw.

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