Essential tremor (ET), an involuntary shaking movement (tremor) that occurs with motion, especially when performing precise fine movement, is the most prevalent movement disorder, and it becomes increasingly frequent with increasing age. The latest issue of The American Journal of Human Genetics now reveals that researchers from Montreal University and its affiliated CHU Sainte-Justine and CHUM hospitals have managed to link some cases of Essential Tremor (ET) to a specific genetic problem.
Researchers and clinicians have investigated for years as to why this shaking occurs, but have so far remained unsuccessful. Even though scientists know that the problem is related to parts of the brain that control certain muscles, they have been unable to identify the exact cause for this malfunction in the nervous system of those affected by ET. Strong evidence of years of research suggested that the disease is due to genetics but until now researchers have been unable to identify the actual genetic link.
The fact that mutations in a gene called FUS (Fused in Sarcoma) cause amyotrophic lateral sclerosis (ALS), a nerve cell disease in the brain and spinal cord that controls voluntary muscle movement, is already known amongst scientists. However, the new study was able to successfully identify mutations that cause ET in FUS, and also managed to provide evidence that the disease mechanisms for ET and ALS FUS mutations are different.
Leading author Dr. Nancy Merner, explained:
“When I started my post-doctoral work in the Rouleau laboratory, I felt compelled to study essential tremor. I saw a great opportunity to identify the first ET gene considering the plethora of families collected for study in the laboratory, and the availability of new sequencing technologies that has revolutionized gene discovery efforts. As a proof of principle study, we chose one family to sequence and took a simple approach to overcome particular clinical barriers that have hindered previous gene discovery attempts.”
Her clinical focus is shared by her other team members. Dr. Guy Rouleau declared:
“This discovery has provided the world with the first insight toward the disease mechanism of essential tremor, which is crucial for disease management, particularly for future drug developments. It also presents a logical approach that can be used for additional ET gene discoveries, which we are currently pursuing.”
Dr. Patrick Dion, another key researcher on this project, added: “There is currently a lack of consensus on the diagnostic criteria of ET thus a genetic diagnosis can be beneficial, especially for familial cases. Transitioning to a genetic diagnosis would cut down on ET misdiagnosis.”
37-50% of individual cases are misdiagnosed.
Affected individuals usually feel embarrassed or annoyed at the tremors that impact their everyday tasks like eating, writing, working, or drinking as these tremors most often affect the hands and make it difficult for those affected to hold or use small objects.
Dr. Merner concludes: “Our overall goal in this endeavor is to improve the quality of life of affected individuals. The road is now paved for improvement.”
Written by Petra Rattue