TRENTON, New Jersey (AP) - An unusual type of bone marrow transplant repaired defective immune systems in several people severely ill with a rare, inherited disease that kills most victims by their 30s, researchers say.

While the approach offers hope for people with chronic granulomatous disease and other genetic disorders, three of the 10 patients died of the disease or treatment complications. Also, it is too soon to say whether the seven others are cured.

But scientists at the National Institute of Allergy and Infectious Diseases said that 18 months later, the seven survivors have much stronger immune systems. Five survivors are children, with the other five patients ages 18 to 36.

"The kids tolerated it better, partly because they were younger and stronger" than adults weakened by repeated infections, said Dr. Mitchell E. Horwitz of the institute's laboratory of host defenses.

The research was reported in Thursday's New England Journal of Medicine.

In chronic granulomatous disease, gene mutations prevent a type of infection-fighting white blood cell from killing bacteria and fungi. That leaves patients vulnerable to life-threatening infections and inflammatory growths that damage the lungs, liver and other organs.

Often, patients with the disease undergo high-dose chemotherapy and radiation to destroy their bone marrow, the body's factory for disease-fighting white blood cells. Then they receive bone marrow transplants from a sibling. The first step of the procedure is dangerous because patients lose most of their defenses against disease.

Under the newer procedure, which is considered safer, patients got low-dose chemotherapy that leaves some of their bone marrow intact. The approach previously had been tried mostly on people with leukemia or kidney cancer.

In three children and two adults, the sibling's bone marrow took over and essentially created a new immune system. In the two other children, part of their immune system is still operating along with the transplanted one.

"They are healthier than they have ever been," Horwitz said. In an editorial, Dr. Alan B. Ezekowitz of MassGeneral Hospital for Children wrote that the transplant is feasible but should be limited for now to adults, because the disease is more likely to kill them soon.

"These new techniques may allow the cure of a wide range of inherited disorders in the next decade," he said.

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