January 28, 2006
Saturday AM

For years, Terry Smith knew that he was distantly related to Abraham Lincoln.

But he didn't know about the illness that ran in his family - what relatives called "Lincoln's Disease."

Now, researchers at the University of Minnesota have uncovered a genetic secret that has plagued the Lincoln family for at least 11 generations: a mutation that causes a form of ataxia, a crippling neurological disease.

The discovery could shed new light on the causes of a number of similar diseases, said Laura Ranum, a university geneticist who led the research project.

But on a historic level, she said, it also raises intriguing new questions about the 16th president, whose health has long been a topic of speculation.

Ranum, who has studied the Lincoln family since 1992, doesn't know whether the president carried the defective gene.

But through genetic detective work, she and her colleagues studied 300 distant cousins of the president (he has no living descendents himself; the last, Robert Todd Lincoln Beckwith, died in 1985). They found that about a third have ataxia, including Smith, of Manteca, Calif.

"My grandma is a Lincoln," said Smith, 57, who learned about the family ailment when he was in his 30s. "Back when my mom was young, it was common knowledge in the family that there was something wrong with the Lincoln family. But they didn't know what it was."

The disease, which usually strikes in adulthood, causes people to lose coordination and have difficulty speaking, writing and walking. Some end up in wheelchairs as the disease progresses.

Ranum, 45, stumbled on the Lincoln family by accident. She was studying how ataxia occurs within families when a colleague told her about an interesting cluster of cases. She called the first family member, and found dozens more eager to talk.

"I was looking just to expand the family history of ataxia," she said.

But the Lincoln connection kept coming up.

She and her colleagues traveled to family reunions and small towns throughout the Midwest (though none in Minnesota) to gather DNA samples and family histories.

To her surprise, she found that all the relatives traced their lineage to the president's uncle, Josiah Lincoln.

Then she found a second branch that descended from Josiah's sister, Mary.

"We knew just from the way it was behaving and the way it was transmitted in the family that it must be a single gene," Ranum said.

Last year, they found it: a genetic mutation on the 11th chromosome that makes a defective protein. Any family member with the gene will get ataxia, Ranum said, "if they live long enough." And their children have a 50 percent chance of getting it, too.

The family tree also told them something else: If Abe's aunt and uncle both had the ataxia gene, that meant one of their parents, Capt. Abraham and Bathsheba Lincoln, must have had it too. And since they were Abe's grandparents, he could have inherited it as well.

There's some evidence he may have, according to Sunday's report by Ranum and her colleagues, physicians John Day and Larry Schut and graduate students Yoshio Ikeda and Katherine Dick.

They note that a British correspondent described Lincoln in 1861 as having an unusual, clumsy gait - one of the traits of ataxia. Of course, others have claimed he had Marfan Syndrome, another genetic disorder, though nothing has ever been proven.

But now, Ranum's team has developed a genetic test for ataxia. And that has raised a tempting prospect. "If we had President Lincoln's DNA, we could test and answer this question," she said. "We would know exactly what to test for."

His DNA is, in fact, preserved in museums - in pieces of bone and bloodstained clothes, for example.

But historians may not be as eager as scientists to find the answer, says Tom Schwartz, a Lincoln historian and research director at the Abraham Lincoln Presidential Library and Museum in Springfield, Ill.

First, he said, testing may damage the historical artifacts. But even if it didn't, he said, "What does it really tell us? And how does this affect our understanding of Lincoln's historical significance? ... It's more kind of idle curiosity."

Ranum, though, says there are contemporary reasons to consider the question. "President Lincoln was a truly great, great leader," she said. "It would do a lot to decrease the stigma of a disability, and to highlight the abilities of people who have ataxia, if he could be that great and have this."

Schwartz, though, sees it differently. "I don't think you need a Lincoln in order to prove that a person with ataxia could do great things," he said.

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