April 21, 2003 -- An "unexpectedly high rate" of genetic abnormalities likely causes a non-inherited form of Lou Gehrig's disease, known medically as ALS or amyotrophic lateral sclerosis.
That's the report from a group of German scientists published in the April 22 issue of Neurology.
Up to 10% of Lou Gehrig's disease cases are hereditary, and several genes have been linked with it. In sporadic or non-hereditary ALS, researchers have identified several genetic risk factors, but they do not fully understand the role genetics play in the disease.
In this study, researchers examined the chromosomes of 85 people with sporadic ALS. Five people had "chromosomal rearrangements" -- 6% of the group, reports lead author Thomas Meyer, MD, of Charite University Hospital in Berlin.
The normal rate of these particular types of chromosomal abnormalities in healthy people is up to .1%, so this is a high rate for people with Lou Gehrig's disease, Meyer explains in a news release. "It's very unlikely that these two conditions could appear together that often and not be related," he says.
It's still not known how the chromosomal rearrangements contribute to ALS, he says. "They may result in the disruption or alteration of susceptibility genes that haven't been identified yet."
Also, an unknown underlying mechanism may promote the development of these chromosomal abnormalities.
When family members of these patients were tested, four out of five had the same chromosomal abnormality but showed no symptoms of Lou Gehrig's disease.
Three of the family members were older -- in their 60s and 70s. This suggests that more than one factor may be necessary for ALS to manifest itself, likely environmental factors, says Meyer.