Familial Aggregation of the Cerebellar Signs in Familial Essential Tremor.
BACKGROUND
Although the hallmark feature of essential tremor (ET) is kinetic tremor, patients may exhibit additional motor features (e.g., intention tremor and mild gait ataxia) that are markers of an underlying abnormality of cerebellar function. ET is also a highly familial disorder, but we do not know whether the presence and expression of cerebellar signs are similar across family members. There are simply no published data. The alternative possibility is that these features are not heritable. We tested the specific hypothesis that the presence of cerebellar signs (i.e., intention tremor, tandem gait difficulty) ran in ET families.


METHODS
ET probands and relatives enrolled in a genetic study at Yale and Columbia universities underwent a detailed videotaped neurological examination.


RESULTS
There were 187 enrollees (59 probands, 128 affected relatives). In a bivariate logistic regression model, the presence of intention tremor in the proband was not a predictor of the presence of intention tremor in the relatives (odds ratio [OR] = 0.60, 95% confidence interval [CI] = 0.28-1.27, p = 0.18). In a similar model, the presence of greater tandem gait difficulty (i.e., a tandem gait score in the upper quartile) in the proband was not a predictor of the presence of such difficulty in the relatives (OR = 1.22, 95% CI = 0.41-3.66, p = 0.73).


CONCLUSIONS
The presence of cerebellar signs did not aggregate in families with ET. In the current dataset, these did not seem to be disease features that were heritable.
Division of Movement Disorders, Department of Neurology, Yale School of Medicine, Yale University, New Haven, CT, USA; Department of Chronic Disease Epidemiology, Yale School of Public Health, Yale University, New Haven, CT, USA; Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine, Yale University, New Haven, CT, USA.
Elan D
ED
Louis
Division of Movement Disorders, Department of Neurology, Yale School of Medicine, Yale University, New Haven, CT, USA.
Nora
N
Hernandez
Division of Movement Disorders, Department of Neurology, Yale School of Medicine, Yale University, New Haven, CT, USA.
Karen P
KP
Chen
Division of Movement Disorders, Department of Neurology, Yale School of Medicine, Yale University, New Haven, CT, USA.
Kelly V
KV
Naranjo
Division of Movement Disorders, Department of Neurology, Yale School of Medicine, Yale University, New Haven, CT, USA.
Jemin
J
Park
Taub Institute for Research on Alzheimer's Disease and the Aging Brain, College of Physicians and Surgeons, Columbia University, New York, NY, USA; Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA.
Lorraine N
LN
Clark
G.H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA; Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA; Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY, USA; Division of Epidemiology, New York State Psychiatric Institute, New York, NY, USA.
Ruth
R
Ottman
Essential tremor; clinical; familial; genetics