Fungus Infected Woman Who Died After Gene Therapy

The 36-year-old Illinois woman who died last month after being treated with an experimental gene therapy was infected with a fungus that usually causes only a mild illness. But the infection spun out of control and ravaged her organs, suggesting that her immune system was seriously impaired, said a doctor who is part of the medical investigation.

The woman's body was also teeming with a cold-sore virus that the body normally keeps in check, another indication of a faltering immune system. And because of a tear inside her abdomen -- perhaps caused by infection, perhaps by injury -- she had an internal blood clot the size of a watermelon.

No formal cause of death has been declared for Jolee Mohr, who died July 24. Mohr had been generally healthy until July 2, when trillions of genetically engineered viruses were injected into her right knee in an experimental treatment for her rheumatoid arthritis.

The injected viruses were genetically modified so they would suppress the immune system -- which is responsible for the inflammation of rheumatoid arthritis -- only in her...