June 12, 2006 — A new treatment has cured basset hounds with bubble boy disease, a life-threatening genetic disorder that disables the immune system, according to a recent study.

The disease, called X-linked severe combined immunodeficiency (XSCID), affects male dogs and around 1 in 100,000 boys, all of whom inherit a faulty gene from one of their mother’s X-chromosomes. The dog study suggests the new treatment may become available to people in future.

At present, there is only one treatment for the disease, which was brought to the public's attention in a popular 1976 film called "The Boy in the Plastic Bubble," starring John Travolta. He played David Vetter, a young man who spent his entire life in a sterilized environment. The real-life Vetter died in 1984.

Boys diagnosed with the condition are given bone-marrow transplants that can replenish stem cells responsible for renewing new functional immune cells.

Gene therapy, in which the individual’s own bone marrow cells are cultured in a lab with the normal gene, showed some success in treating 10 of 11 boys during a 1999 French study. But three of the test subjects later developed leukemia related to the process.

"Although ex-vivo (outside of the body) gene therapy has been shown to be capable of restoring normal immune function in XSCID boys, there are several potential problems with this approach," said Peter J. Felsburg, who led the recent work and is a professor of immunology at the University of Pennsylvania's School of Veterinary Medicine.

Felsburg and his colleagues tried a new approach by directly injecting the corrected gene via an engineered virus into the bloodstream of four "bubble boy" basset hounds. Three of the four dogs have maintained healthy immune systems over a year after receiving the genes. The fourth dog received a lower dosage, which suggests there is a lower limit to the dose before the gene can restore immunity.

Findings were recently published in the journal Blood.

Jennifer Puck, who is a researcher in the Division of Immunology & Rheumatology at the University of California, San Francisco, is a leading expert on XSCID and related immunodeficiency diseases. At the April conference Primary Immunodeficiencies: Past, Present, Future, Puck presented information on a new method she and her colleagues have developed for diagnosing the diseases in young infants.

Puck told Animal Planet News that the basset hound treatment "is a great idea, but its application to humans is far in the future. It is still way to early to say that it is safe."

She explained that the French children who developed leukemia did not become ill until 30-34 months after the treatment.

Puck, however, welcomes new methods for curing immunodeficiency diseases, which can affect both boys and girls. XSCID, which only affects boys, is just one of many related conditions.

"Newborns affected with severe immunodeficiency look completely healthy at first because they have antibodies from their mother," Puck said. "Unfortunately, something really serious has to happen before the genetic disease is suspected, but by then, the baby often is not in good shape."

She hopes universal screening soon will look for the diseases in all babies when they have their blood tests shortly after birth.