Mild tremor in relatives of patients with essential tremot: What does this tell us about the penetrance of the disease?

Elan D. Louis, Blair Ford, Steven Frucht, Ruth Ottman

Research output: Contribution to journalArticle

33 Scopus citations

Abstract

Background: Mild tremor may occur in relatives of patients with essential tremor (ET). However, this phenomenon has not been studied quantitatively or with a comparison group. Such a study may provide information on the penetrance of ET. Objective: To obtain data on the magnitude of tremor in case and control relatives who did not meet diagnostic criteria for ET. Methods: Cases with ET and control subjects from the Washington Heights-Inwood community in northern Manhattan, NY, were enrolled in a family study. Their first- and second-degree relatives underwent a videotaped tremor examination. Two neurologists rated the severity of tremor, assigning a total tremor score (0-36 [maximum]). Data were analyzed on 201 case relatives and 212 control relatives who did not meet diagnostic criteria for ET. Results: The mean total tremor score of first-degree case relatives was higher than that of first-degree control relatives (4.9 vs 3.9; P<.003). Total tremor scores for seconddegree relatives did not differ (4.1 vs 4.2; P=.68). A larger percentage (55.2% vs 36.6%; P=.01) of first-degree case relatives had total tremor scores of 4 or more. Among firstdegree relatives who were older than 60 years, 13 case relatives (59.1%) and 18 control relatives (45.0%) had total tremor scores of 4 or more. Conclusions: A considerable number of seemingly normal case relatives may have a genetic predisposition for tremor. Even among older case relatives (≥60 years of age), there was an increased prevalence of higher tremor scores, suggesting that in that age group, subclinical ET may be present and penetrance still may not be complete.

Original languageEnglish (US)
Pages (from-to)1584-1589
Number of pages6
JournalArchives of neurology
Volume58
Issue number10
DOIs
StatePublished - Jan 1 2001
Externally publishedYes

ASJC Scopus subject areas

  • Arts and Humanities (miscellaneous)
  • Clinical Neurology

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