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Parkinsonism Relat Disord. 2018 Jul;52:24-29. doi: 10.1016/j.parkreldis.2018.03.011. Epub 2018 Mar 13.

Unaffected first-degree relatives of essential tremor cases have more imbalance than age-matched control subjects.

Author information

1
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. Electronic address: elan.louis@yale.edu.
2
Department of Neurology, Yale School of Medicine, Yale University, New Haven, CT, USA.
3
Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY, USA.

Abstract

BACKGROUND:

Endophenotypes are measurable clinical characteristics that may be present in individuals with increased risk for disease (e.g., unaffected family members). Endophenotypes are useful; they may clarify diagnosis in genetic studies and foster the development of animal models. In recent years, problems with balance and mild gait ataxia have been associated with essential tremor (ET). We compared gait and balance of first-degree relatives of ET cases (FD-ET) to that of age-matched controls (Co).

METHODS:

One-hundred-ninety FD-ET and 68 Co, none of whom reported tremor or were diagnosed with ET, underwent a standardized assessment of gait and balance.

RESULTS:

FD-ET reported more near-falls in the past year (p = 0.015) and lower balance confidence according to the Activities of Balance Confidence (ABC-6) Scale (p = 0.03). The specific ABC-6 items for which FD-ET reported lower balance confidence than Co were being bumped into by people while walking (p = 0.006) and walking outside on icy sidewalks (p = 0.007). On videotaped neurological examination, FD-ET were able to stand in the tandem position for fewer seconds than were Co (p = 0.048). The differences between FD-ET and Co, although statistically significant, were clinically mild.

CONCLUSION:

FD-ET reported more near-falls in the past year and a reduction in balance confidence; additionally, ability to maintain tandem stance was impaired compared to Co. These data suggest a more pervasive abnormality of cerebellar dysfunction than previously conceived, extending beyond ET cases themselves and manifesting in mild form in their unaffected family members.

KEYWORDS:

Balance; Endophenotype; Epidemiology; Essential tremor; Gait; Genetics

PMID:
29551395
PMCID:
PMC6019168
[Available on 2019-07-01]
DOI:
10.1016/j.parkreldis.2018.03.011

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