MONDAY, Jan. 29 (HealthDay News) -- Tiny worms are revealing important clues to ataxia, a rare, debilitating neurodegenerative disorder that may have affected President Abraham Lincoln.
A new study suggests that the defective gene behind spinocerebellar ataxia type 5 (SCA5) causes nerve cells to snap under the strain of everyday movement and eventually die.
Last year, researchers at the University of Minnesota used DNA from Lincoln's descendants to pinpoint a defect in a particular gene as the cause of SCA5. Nearly one-third of the 299 descendants studied already showed symptoms of the illness.
The very rare disease, which has no cure, typically begins later in life and causes a gradual loss of coordination over time that leaves many patients wheelchair-bound.
Eyewitness accounts noted the older Lincoln's "shambling, loose, irregular, almost unsteady gait," typical of early stage SCA5. While there is no conclusive proof that the 16th president suffered from the illness, Lincoln's grandmother or grandfather did carry the defective gene, experts say, giving him a 25 percent chance of being affected.
Now, a team of researchers at the University of Utah says its study using the Caenorhabditis elegans worm -- a common animal model for research -- points to a novel mechanism driving SCA5.
According to the study, the implicated gene mutation may cause axons -- the long, skinny arms that extend out from nerve cells -- to become much less flexible and then break as an organism moves about.
"The structure of the neurons is normal during development and at birth, but it progressively deteriorates over time. And, when we looked closely at this, we found that it is deteriorating because the axons break," said senior researcher Michael Bastiani, professor of biology at the University of Utah's Brain Institute in Salt Lake City.
His team published its findings in the Jan. 29 issue of the Journal of Cell Biology.
This slow but steady breakage and re-breakage of axons eventually causes nerve cells to lose their ability to regenerate, Bastiani said. This could explain why the loss of coordination and gradual disability seen in SCA5 doesn't really begin to appear until late childhood or even much later in adulthood, he added.
