Goldman SM, et al. – In this study, researchers assessed the genetic contribution to Parkinson's disease risk in a large population-based twin registry during the 1990s. Since many uninfluenced twins were still alive, previous estimates of concordance were based on incomplete information. Using National Death Index data, they updated concordance and heritability up to 2015. A total of 30 concordant and 193 discordant pairs were identified. Data reported that the concordance in probandwise was 0.20 in monozygotic and 0.13 in dizygotic pairs. The overall inheritance was 0.27, 0.83 in pairs diagnosed < 50, and 0.19 in pairs diagnosed > 50. According to findings, high concordance in dizygotic twins suggested that early childhood environment has shared effects.