Motor neuron disease (MND), in which the nerve cells that carry brain signals gradually deteriorate, may be triggered by environmental toxins, say a team of University of Michigan (UM) scientists. Writing in the March issue of the American Journal of Human Genetics, the researchers explained that the finding could be the first step in uncovering a possible link between chemicals in the environment and motor neuron disease. The researchers discovered that a mutation in one key gene (neuropathy target esterase, or NTE) causes a previously unknown type of inherited motor neuron disease. But most intriguingly, the scientists found that the mutations caused changes in a protein already known to be involved when people develop neurologic disorders as a result of exposure to toxic organophosphates - chemicals commonly used in solvents and insecticides.
"We speculate there may be gene-environment interactions that cause some forms of motor neuron disease," says John K. Fink, professor of neurology at UM. "Our findings support the possibility that toxic organophosphates contribute to motor neuron disease in genetically vulnerable people," he added.
Tellingly, there have been recent incidents in Fiji, India and Africa when accidental consumption of oils containing neurotoxic organophosphates (instead of cooking oil) caused death or nerve damage for tens of thousands of people. Although scientists don't yet know the exact manner in which toxic organophosphate exposure leads to progressive and permanent nerve damage, they have learned that this process involves disturbance of an enzyme, NTE, contained within nerves.
Next, Fink and his team want to learn if mutations in the NTE gene happen in other types of motor neuron disease, and if the mutations make a person more vulnerable to neurological damage from organophosphate exposure. Fink's lab is currently using fruit flies as a model to study the NTE mutations, with the goal of finding treatments for people with motor neuron disease.
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Source: University of Michigan Health System
