Essential tremor causes involuntary shaking in the arms and hands, and sometimes in the neck, jaw and voice as well. Though sometimes mistaken for Parkinson’s disease, the two conditions differ in terms of cause, symptoms, treatment and outlook.
Essential tremor is not life threatening, but it can interfere with daily activities such as drinking, writing and even speaking. The NIH estimates that essential tremor affects as many as 14% of people over the age of 65.
It is suspected that a combination of environmental and genetic factors contributes to essential tremor, but so far no genetic factors have been definitively linked to the disease. Now, in a report published online yesterday by the journal Nature Genetics, researchers have identified for the first time a specific genetic variant that is significantly associated with essential tremor. Their findings connect essential tremor to a gene involved in nerve cell maintenance and survival, and could pave the way to the development of new therapeutics.
In a combined analysis of 752 subjects with essential tremor from Iceland, Austria, Germany and the United States and 15,797 controls, Stefansson et al found that the G version of rs9652490 in the LINGO1 gene is associated with increased odds of the condition.
Carrying one G increases the odds of essential tremor by 1.55 times compared to two As. The approximately 5% of the population with European ancestry with two Gs has 2.40 times increased odds.
The authors note that because of the way study subjects with essential tremor were recruited, they probably represent a more genetically-rooted, early onset form of the disease than would be seen in the population in general.
LINGO1 encodes a protein that is involved in regulating nerve cell growth, survival and specialization. Increased LINGO1 levels have been seen in people with multiple sclerosis and Parkinson’s disease. This suggests that drugs made to block the action of LINGO might be valuable for treating some diseases of the central nervous system. The authors suggest that their finding linking a change in LINGO1 to essential tremor should put this condition at the top of the list of diseases to be assessed.
“Association of essential tremor with LINGO1 opens up a new field in the research into essential tremor, and it is our hope that LINGO1 will point the way to new treatments for severe cases of the disease,” the authors conclude.