During his five years as a backup quarterback for the San Francisco 49ers, Bob Waters, now 48, suffered more than his share of bruises and broken bones. Thus when he began to experience some shakiness in his right arm more than four years ago, he simply chalked it up to an old playing injury that had been repaired with a metal plate. "My doctors and I decided that, well, maybe it has something to do with the metal," says Waters, who coaches at Western Carolina University. But gradually, as the muscle spasms spread and both arms weakened, Waters became alarmed. In February 1985 doctors confirmed his worst fear: he was suffering from amyotrophic lateral sclerosis, a progressive weakening of the muscles due to nerve degeneration.
Commonly known as Lou Gehrig's disease, after the brilliant New York Yankee first baseman whose career and life it cut short, ALS is generally fatal. Among its better-known victims: Actor David Niven and former New York Senator Jacob Javits. Though the cause remains elusive, doctors suspect that genetic susceptibility sometimes plays a role: 5% to 10% of ALS patients have a family history of the disorder. Some researchers consider it to be an autoimmune disease, in which the victim's immune system assaults his own body tissue.
In Waters' case, however, this seemingly random stroke of misfortune soon began to look like a clue to a medical mystery. Shortly after his diagnosis, Waters learned that his former teammate Matt Hazeltine, a linebacker, had also been stricken with ALS. Last December Waters heard of a third ALS casualty from the 1964 squad -- Fullback Gary Lewis. Both Hazeltine and Lewis died earlier this winter. Waters was stunned. Was it mere coincidence? The disease typically strikes 1 in 50,000 Americans a year, yet it hit three teammates on a 55-man squad. Waters' doctor, Stanley Appel, head of neurology at Houston's Baylor College of Medicine, was suspicious too. "Statisticians would tell you that there is still a possibility it's due to chance," he says. "But no matter how you figure it, 3 out of 55 is way out of proportion."
The trio of cases does not represent the first instance in which ALS has been found in tantalizing clusters. In Ohio three teachers who taught in the same high school classroom developed the disease. So did six people living on the same hillside behind the Berkeley campus of the University of California. The most widely studied clusters are located in the western Pacific, particularly on the island of Guam, where ALS was once at least 50 times as common as in the continental U.S. Last year Peter Spencer, a neurotoxicologist at New York City's Albert Einstein College of Medicine, offered a solution to the mystery of the Guamanian cases when he traced them to a toxin found in cycad seeds, which the natives used to eat in times of famine. The toxin specifically affects nerve cells, says Spencer, and "exposure may occur decades before the actual onset of the disease."
While Spencer's discovery cannot directly explain the cases of the San Francisco 49ers or the Ohio schoolteachers, it does lend credence to the notion that something toxic in diet or environment can later trigger ALS. Indeed, over the years, a befuddling array of culprits has been suggested. They include infection with poliovirus, exposure to heavy metals, employment in the plastics industry and a history of traumatic injuries.