Concordance for Parkinson's disease in twins: A 20-year update.
Level 3 - non-randomized controlled study
Longitudinal twin cohort study assessing disease concordance and heritability
PubMed 30786044 · doi:10.1002/ana.25441
What was done
Researchers updated concordance and heritability estimates for Parkinson's disease in a large population-based twin registry through 2015 using National Death Index data, after 95% of the twins were deceased.
What was found
The study identified 30 concordant and 193 discordant pairs. Proband-wise concordance was 0.20 in monozygotic twins and 0.13 in dizygotic twins. Estimated heritability was 0.27 overall, 0.83 in twin pairs diagnosed at or before age 50, and 0.19 in pairs diagnosed after age 50.
Why it matters
Near-lifetime follow-up reveals that early-onset Parkinson's disease is predominantly driven by genetic factors, whereas late-onset disease shows substantial environmental contribution.
Limits
Follow-up relied on National Death Index records rather than continuous clinical examinations. The abstract omits confidence intervals and exact counts of monozygotic versus dizygotic pairs stratified by age.
Cited by
- supports Twin studies show that Parkinson's disease is only about 20% to 30% heritable/genetic.