WASHINGTON (AP) _ The University of Pennsylvania told the federal government Monday an Arizona teen-ager's death from a gene therapy experiment was an unavoidable tragedy, not the result of research violations.

The Food and Drug Administration last month suspended all the university's gene therapy studies, citing 18 rule violations in the experiment that killed 18-year-old Jesse Gelsinger, of Tucson, Ariz., last fall.

On Monday, the university filed a response with the FDA acknowledging some ``procedural'' problems but disagreeing with some of the charges.

The university insisted it immediately notified the FDA of Gelsinger's death, fully cooperated in the ensuing investigation, and that none of the alleged violations would have changed Gelsinger's care.

``With the best medical judgment and scientific information we had, we just didn't anticipate _ nor in retrospect do we believe we could have anticipated _ this tragic event,'' said Dr. Richard Tannen, the university's medical vice dean.

Gelsinger's liver was injected with a virus bearing genes designed to correct a genetic liver disorder. He suffered a toxic reaction and died four days later. It was the first death attributed to experimental gene therapy.

The FDA has charged that researchers delayed reporting two previously treated patients who suffered liver toxicity, and that two monkeys died in a similar experiment. The FDA also questioned whether study participants were properly informed of the risks.

Earlier this month, Gelsinger's father told Congress researchers ``misled'' him about the study's safety.

The university delayed telling FDA about the sick patients, but did do so six months before Gelsinger was treated and FDA never stopped the experiment, Tannen said.

As for the dead monkeys, he said FDA should have been notified but insisted the monkeys received far higher doses than Gelsinger.

The university insisted patients were properly informed about the risks. But it already has taken steps to improve oversight of clinical trials, Tannen said.

The FDA said its investigation continues.