Andrew Mattingly Jackson Jr. whirs his three-wheeled electric cart into a paneled dining room in a nursing home in Silver Spring, hurrying to join a gathering of his relatives.
Waiting for him is John Philip Mattingly, a resident of the home. He nudges his right hand against the control stick of his electric wheelchair, spinning to greet Mr. Jackson face to face. One by one, the rest arrive: Anna Mae in her wheelchair; Jay with his cane and plastic ankle braces; Bonnie and then Janet, both with a telltale hesitation in their step.
They've come to share news about children and spouses and jobs. And about the tragic legacy they all share.
For seven generations, the descendants of George Washington Mattingly, born in St. Mary's County in 1792, have been shadowed by a baffling illness that can slow, hobble and finally cripple sufferers.
Now investigators at Johns Hopkins University and the University of Pennsylvania, using the recently developed tools of molecular genetics, are trying to solve that mystery. They're hunting for the gene that causes the disorder, which affects at least 70 of about 150 known descendants of George Mattingly.
And, while it may take a year or longer, they expect to find it.
Over the past century, the family disorder has remained beyond the reach of scientific breakthroughs in medicine: in antibiotics, surgery and vaccines. That's because the disorder is not caused by a viral infection, trauma or outside cause. It lies within.
But the current revolution in genetics offers younger Mattinglys a measure of hope.
Discovery of the gene will probably yield a test that will alert potential victims. One day, it could lead to a treatment, or even a cure.
Unlike some other inherited neuromuscular diseases, the Mattingly disorder does not shorten a person's lifespan. Still, family members could face some hard questions. If a prenatal test were positive, should parents terminate a pregnancy? Would teen-agers or young adults with no symptoms really want to know they face paralysis?
Today, these issues are purely hypothetical. The Mattinglys are eager to see the Hopkins-Penn team track down the gene.
None seems more eager than Andrew Mattingly Jackson Jr., a 67-year-old retired Black & Decker manager from Hampstead.
"I'm getting to the point where I have to have an aide to dress and undress me, to shower me, to lift me off and on the john," says Mr. Jackson, talking with a reporter during a break in the gathering. "I can't bring food up to my face. I have very little use of my hands."
He grows silent, then raises his stricken hands, palms upward.
Mr. Jackson first sought treatment in 1947, after he struggled to climb ladders while serving aboard a Navy ship. At the Pensacola Naval Hospital, he was misdiagnosed with a lethal illness -- amyotrophic lateral sclerosis (ALS), or Lou Gehrig's disease -- and discharged.
A few months later, a Johns Hopkins physician told him he had Charcot-Marie-Tooth, or CMT -- a nonfatal, inherited, muscular disorder.
In 1963, researchers at the National Institutes of Health launched the first full-scale study of the Mattinglys' ailment. They, too, labeled it a form of CMT. Hopkins physicians conducted another, more limited study 13 years later, in 1976.
In these early research efforts, scientists lacked the modern tools to track down the ultimate cause of the disease -- the gene itself. But they were able to catalog its effects and compile a partial family tree that traced the illness among Mattingly descendants, confirming its genetic basis.
After his discharge from the Navy, Mr. Jackson started his own family. He had two sons.
One, Dwight David Jackson, inherited the disorder.
"We noticed something wrong with him when he was 7 or 8 years of age," Mr. Jackson recalled. "That kind of devastated me. I was thinking of what lay in store for him."
Mr. Jackson's concern for his son accelerated as his own strength ebbed.
He attended meetings of CMT sufferers. He expanded the NIH's Mattingly family tree, now an 86-page catalog of births, deaths and marriages spanning more than 300 years. He pored over newsletters published by a CMT support group, and wrote articles for it.
Jay Lane, 42, of Takoma Park, learned that he had the family illness in 1990 while reading an article Mr. Jackson wrote in a newsletter for CMT sufferers.
"It all clicked then," Mr. Lane said. "My grandmother was from St. Mary's County, born and raised there, and she was a Mattingly. I just called him up and said, 'Hey, we could be related. Could we have the same thing?' "
Mr. Jackson wrote letters to Mattinglys all over the country and in England in an unsuccessful search for affected relatives. (Thomas Mattingly, the first member of the family to arrive in St. Mary's County, emigrated from England in the 1600s.)
Astonishingly, the afflicted descendants now all seem to live in Maryland. Branches of the family living in Texas and the Midwest, including that of pro baseball player Don Mattingly, apparently are not affected.