Jett Travolta,John Travolta's 16-year-old Son Dies in Bahamas

Actress Kelly Preston has said her 16-year old son with husband John Travolta became very sick when he was 2 and was diagnosed with Kawasaki disease, an illness that affects the blood vessels in young children.The boy, Jett Travolta, died Friday after suffering a seizure at the family's vacation home in the Bahamas, though it wasn't immediately clear whether the death was related to his illness. The boy was found in a bathtub, where he reportedly fell and hit his head.

In a 2003 interview on the Montel Williams show, Preston talked about her son's struggle with Kawasaki disease. "It causes swelling in the organs, so your heart can swell, different important organs can swell," she said. "We thought at one point we were going to lose him."

Dr. Scott Alenick, a pediatric cardiologist in New Jersey, told FOXNews.com in an interview last year that Kawasaki disease is a condition that affects children, especially boys under the age of 5, and causes aneurysms and blockages in the blood vessels.

"We usually see it in the winter, but it can occur year-round,” Alenick, who has treated hundreds of cases of Kawasaki disease, said. “It is very unusual to die from Kawasaki disease.”According to the American Heart Association, more than 4,000 cases of the disease are diagnosed annually in the United States. It occurs more often in boys of Japanese and Korean descent, but has been identified in children of all ethnicities and races, Alenick said.

While the condition is not preventable, it is treatable with most children recovering from the disease. In fact, less than 1 percent of Kawasaki cases are fatal.The danger of Kawasaki syndrome is that it can cause large aneurysms in the blood vessels that feed blood to the heart, said Alenick.

“Kawasaki doesn’t come in degrees of severity, but it varies in that it may cause no aneurysms, small aneurysms, moderate aneurysms or giant aneurysms,” he said. “Giant aneurysms are more common in babies. But it’s the aneurysms that form in the vessels and the arteries that feed the heart that have the potential to cause a fatal heart attack.”

The disease was first identified in Japan in 1967 by Dr. Tomisaku Kawasaki, and the cause of the illness is still unknown, Alenick said. There also is no blood test to identify the illness. Instead, patients are given a clinical diagnosis based on whether they display at least five of these six symptoms: a high fever that lasts for more than five days, red lips and tongue, swelling of the hands and feet, bloodshot eyes, rash and swollen glands.Jett Travolta was pronounced dead at Rand Memorial Hospital, police said, and an autopsy is being scheduled.