The death of 16-year-old Jett Travolta, the son of actors John Travolta and Kelly Preston, has triggered a controversy involving autism, a rare childhood disorder called Kawasaki Disease and the parents' Scientology beliefs.

Jett Travolta was found unconscious in the family's vacation home bathroom in the Bahamas on Friday and could not be revived. An autopsy was performed yesterday.

Glen Campbell, assistant director of the Bahamian funeral home handling the remains of Jett Travolta, told The Associated Press that the death certificate said he was killed by a "seizure" and that the body showed no sign of head trauma, despite police officials who had said the teen hit his head on a bathtub.

Mr. Travolta and Ms. Preston have never said that Jett had autism, but his sometimes disconnected behavior in public and his history of seizures had led some autism groups to suggest he had the disorder.

Autism United, an advocacy group, said that "this is a difficult time for John and Kelly, and our prayers are with them, but this could be an opportunity for them to use their son's death and their celebrity to help thousands of parents who are caring for sick youngsters."

Although Scientology is well-known for its opposition to the use of psychotropic drugs for mental disorders, it also has endorsed drug use and other standard treatments for physical ailments, and there has been no indication of whether Jett Travolta was getting treatment for his frequent seizures.

Jett's parents said he suffered from the lingering effects of Kawasaki Disease, which Ms. Preston blamed on household cleaning chemicals and pesticides that had wafted into their home from a nearby golf course.

But an expert on that disorder said yesterday that Kawasaki does not tend to cause seizures later in life, and that there is no evidence that it is triggered by environmental toxins.

Dr. Vivek Allada, clinical director of pediatric cardiology at UPMC Children's Hospital of Pittsburgh, said Kawasaki is characterized by a high, spiking fever in young children that lasts for several days and by rashes on the mouth, lips and throat, as well as swollen lymph glands, feet and hands.

If it is treated quickly with immunoglobulins, he said, most children suffer no permanent damage.

In about 3 percent of the cases, though, children will develop aneurysms -- balloon-like swellings -- in their coronary arteries, and that can sometimes cause heart attacks later in life.

While children can have seizures during periods of high fevers, Kawasaki does not appear to cause seizures once the fevers disappear, and there is no evidence that it leads to behavioral abnormalities, Dr. Allada said.

One study several years ago suggested carpet cleaning might trigger Kawasaki, but the prevailing theory is that a virus or bacteria may kick it off in children who have a genetic susceptibility to the disorder, he said.

But in a 2003 appearance on the Montel Williams show, Ms. Preston said she believed her son's Kawasaki was triggered by household chemicals and pesticides, and said she used a technique developed by Scientology founder and science fiction author L. Ron Hubbard to detoxify her son and herself.

She did not refer in the program to any seizures or to autism.

Even though it is now the leading cause of acquired heart disease in children, Dr. Allada said, Kawasaki affects only about 4,000 children a year in the United States, making it relatively rare.

One reason for the speculation about Jett Travolta having autism is that seizures are much more common in people with autism than in the general population.

Dr. Nancy Minshew, director of the University of Pittsburgh's Center for Excellence in Autism Research, said one long-term study showed that up to 30 percent of all those diagnosed with autism may develop epilepsy.

The seizures are sometimes missed, she said, because they may manifest themselves as episodes of irritability or even rage, and that sometimes leads doctors to prescribe psychotropic medications that can actually trigger seizures more quickly.

No one knows why seizures are more common in people with autism, Dr. Minshew said, but there is some evidence that those with autism have fewer inhibitory brain chemicals than other people do, "so you might have more excitation going on" in their brains.