WASHINGTON (Reuters) -- A patient who became ill following two experimental gene therapy injections for arthritis has died and U.S. health regulators are investigating the cause, officials said on Thursday.

The gene therapy trial by Targeted Genetics Corp. was placed on hold before the death, after the patient suffered a serious, unidentified health problem. The hold means that no one else can receive the treatment, called tgAAC94, and no new patients can be enrolled in the study, the Food and Drug Administration said. Gene therapy aims to replace a faulty gene with a healthy one. Often a virus is used to carry a new gene into cells