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. 1999 Jan 27;281(4):341-6.
doi: 10.1001/jama.281.4.341.

Parkinson disease in twins: an etiologic study

C M Tanner  1 , R Ottman, S M Goldman, J Ellenberg, P Chan, R Mayeux, J W Langston
Affiliations

Parkinson disease in twins: an etiologic study

C M Tanner et al. JAMA. .

Abstract

Context: The cause of Parkinson disease (PD) is unknown. Genetic linkages have been identified in families with PD, but whether most PD is inherited has not been determined.

Objective: To assess genetic inheritance of PD by studying monozygotic (MZ) and dizygotic (DZ) twin pairs.

Design: Twin study comparing concordance rates of PD in MZ and DZ twin pairs.

Setting and participants: A total of 19842 white male twins enrolled in the National Academy of Sciences/National Research Council World War II Veteran Twins Registry were screened for PD and standard diagnostic criteria for PD were applied. Zygosity was determined by polymerase chain reaction or questionnaire.

Main outcome measure: Parkinson disease concordance in twin pairs, stratified by zygosity and age at diagnosis.

Results: Of 268 twins with suspected parkinsonism and 250 presumed unaffected twin brothers, 193 twins with PD were identified (concordance-adjusted prevalence, 8.67/1000). In 71 MZ and 90 DZ pairs with complete diagnoses, pairwise concordance was similar (0.129 overall, 0.155 MZ, 0.111 DZ; relative risk, 1.39; 95% confidence interval, 0.63-3.1). In 16 pairs with diagnosis at or before age 50 years in at least 1 twin, MZ concordance was 1.0 (4 pairs), and DZ was 0.167 (relative risk, 6.0; 95% confidence interval, 1.69-21.26).

Conclusions: The similarity in concordance overall indicates that genetic factors do not play a major role in causing typical PD. No genetic component is evident when the disease begins after age 50 years. However, genetic factors appear to be important when disease begins at or before age 50 years.

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Comment in

  • Understanding Parkinson disease.
    Cummings JL. Cummings JL. JAMA. 1999 Jan 27;281(4):376-8. doi: 10.1001/jama.281.4.376. JAMA. 1999. PMID: 9929094 No abstract available.
  • Parkinson disease in twins.
    Parker WD Jr, Swerdlow RH, Parks JK, Davis JN 2nd, Trimmer P, Bennett JP, Wooten GF. Parker WD Jr, et al. JAMA. 1999 Oct 13;282(14):1328; author reply 1328-9. JAMA. 1999. PMID: 10527169 No abstract available.
  • Parkinson disease in twins.
    Simon DK. Simon DK. JAMA. 1999 Oct 13;282(14):1328; author reply 1328-9. JAMA. 1999. PMID: 10527170 No abstract available.

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