Systematic analysis of clinical features and gene mutations has not been performed in Korean patients with early-onset Parkinson disease (PD).
To investigate the clinical characteristics and genetic background of Korean patients with early-onset PD.
Clinical and genetic study.
Ninety-four patients with early-onset PD (mean ± SD age at onset, 39.8 ± 7.3 years) of 1100 patients with PD.
Analysis of clinical characteristics and mutation analysis of the parkin and PTEN-induced kinase (PINK1) genes by direct sequencing and gene-dosage analysis using the multiplex ligation–dependent probe amplification technique.
Main Outcome Measures
The correlation between age at onset and clinical characteristics and the clinical features of patients with onset before age 30 years vs patients with onset after age 30 years.
Because age at onset was younger, levodopa-induced dyskinesia and off-dystonia were more frequently observed (P=.008). Patients affected before age 30 years showed more frequent levodopa-induced dyskinesia and off-dystonia (P=.002). We identified 3 patients (5%) with parkin gene mutations but none with the PINK1 mutation.
Earlier onset of levodopa-induced dyskinesia and off-dystonia were characteristic features of early-onset PD, especially before an onset age of 30 years. However, parkin gene mutations were less frequent in these patients than in Japanese groups reported elsewhere.