Public release date: 11-Sep-2012 [ | E-mail | Share ]

Contact: Raymond MacDougall macdougallr@mail.nih.gov 301-402-0911 NIH/National Human Genome Research Institute

Researchers have demonstrated that a refined gene therapy approach safely restores the immune systems of some children with severe combined immunodeficiency (SCID). The rare condition blocks the normal development of a newborn's immune system, leaving the child susceptible to every passing microbe. Children with SCID experience chronic infections, which usually triggers the diagnosis. Their lifespan is two years if doctors cannot restore their immunity.

The findings from facilities including the National Institutes of Health, the University of California, Los Angeles (UCLA), and the Children's Hospital Los Angeles, are reported in the Sept. 11, 2012, advanced online issue of the journal Blood, the official journal of the American Society of Hematology.

In the 11-year study, the researchers tested a combination of techniques for gene therapy, arriving at one that produced normal levels of immune function for three patients.

"Doctors who treat patients with SCID have had limited treatment options for too long," said Dan Kastner, M.D., Ph.D., scientific director of the National Human Genome Research Institute (NHGRI), part of the NIH. "The research teams and the patients who have participated in the studies have together achieved an impressive advance toward a cure that is welcome news for both the scientific and patient communities."

Gene therapy is an experimental method for treating patients with genetic diseases. It is intended to integrate functioning genes among those naturally existing in the cells of the body to make up for faulty genes. Researchers in the current study tested a set of methods to improve outcomes for children with a particular form of SCID.

"This is a highly rewarding study for those of us in the clinic and lab," said Fabio Candotti, M.D., a senior author and a senior investigator in NHGRI's Genetics and Molecular Biology Branch. "Not only have we realized an important advancement in gene therapy, but we have seen a renewal of health in our patients."

While rare, SCID became widely known because of the remarkable boy-in-the-bubble story of the 1970s. The story was based in part on a boy named David Vetter, who lived for 13 years in a plastic isolation unit to protect him from infections. He died following an unsuccessful bone marrow transplant that doctors had hoped would repair his immune system.

SCID has many causes. In one type, a gene that produces the adenosine deaminase (ADA) enzyme becomes mutated and fails to produce the normal enzyme. Without ADA, a chemically altered form of adenosine, one of DNA's building blocks, accumulates in rapidly dividing bone marrow cells, killing them and destroying the immune system in the process. Normal bone marrow makes healthy white blood cells, or lymphocytes, which are the key players in the immune response that reacts against harmful bacteria and destroys cells infected by viruses. ADA deficiency accounts for some 15 percent of SCID cases.

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NIH researchers restore children's immune systems with refinements in gene therapy