Article  |   April 2012
Genetic and Environmental Effects on Vocal Symptoms and Their Intercorrelations
 
Author Affiliations & Notes
  • Ida Nybacka
    Åbo Akademi University, Turku, Finland
  • Susanna Simberg
    Åbo Akademi University, Turku, Finland
  • Pekka Santtila
    Åbo Akademi University, Turku, Finland
  • Eeva Sala
    Turku University Central Hospital, Turku, Finland
  • N. Kenneth Sandnabba
    Åbo Akademi University, Turku, Finland
  • Correspondence to Susanna Simberg: susanna.simberg@abo.fi
  • Editor: Anne Smith
    Editor: Anne Smith×
  • Associate Editor: Robert Hillman
    Associate Editor: Robert Hillman×
  • © 2012 American Speech-Language-Hearing AssociationAmerican Speech-Language-Hearing Association
Article Information
Speech, Voice & Prosodic Disorders / Voice Disorders / Special Populations / Genetic & Congenital Disorders / Speech
Article   |   April 2012
Genetic and Environmental Effects on Vocal Symptoms and Their Intercorrelations
Journal of Speech, Language, and Hearing Research, April 2012, Vol. 55, 541-553. doi:10.1044/1092-4388(2011/10-0188)
History: Received July 1, 2010 , Accepted July 26, 2011
 
Journal of Speech, Language, and Hearing Research, April 2012, Vol. 55, 541-553. doi:10.1044/1092-4388(2011/10-0188)
History: Received July 1, 2010; Accepted July 26, 2011
Web of Science® Times Cited: 1

Purpose: Recently, Simberg et al. (2009)  found genetic effectson a composite variable consisting of 6 vocal symptom items measuring dysphonia. The purpose of the present study was to determine genetic and environmental effects on the individual vocal symptoms in a population-based sample of Finnish twins.

Method: The sample comprised 1,728 twins (125 monozygotic and 108 dizygotic twin pairs) born between 1961 and 1989, who completed a questionnaire concerning 6 vocal symptoms. Values for additive genetic, dominant genetic, shared environmental, and nonshared environmental components were computed separately for all symptoms. Multivariate analyses to determine genetic and environmental associations between the vocal symptoms were also performed.

Results: Variance was explained by significant additive genetic effects (27%) in only one of the vocal symptoms, namely, voice gets low or hoarse, whereas the variance of one of the vocal symptoms, voice gets strained or tires, could be explained by nonshared environmental influence alone. Multivariate analyses showed that the correlations for most of the symptom combinations were significant.

Conclusions: Both genetic and environmental components influence vocal symptoms. Genetic and environmental influences seem to be differently balanced in different vocal symptoms. Genetic effects are moderate, whereas environmental effects seem to be the most important factor contributing to the presence of vocal symptoms.

Acknowledgment
This research was financed by Grant 210298 from the Academy of Finland and a Centre of Excellence Grant from the Stiftelsen för Åbo Akademi Foundation.
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