title: Clinical features and gene analysis in Korean patients with early-onset Parkinson disease.
abstract: BACKGROUND
  Systematic analysis of clinical features and gene mutations has not been performed in Korean patients with early-onset Parkinson disease (PD).
  
  
  OBJECTIVE
  To investigate the clinical characteristics and genetic background of Korean patients with early-onset PD.
  
  
  METHODS
  Clinical and genetic study.
  
  
  METHODS
  University hospital.
  
  
  METHODS
  Ninety-four patients with early-onset PD (mean +/- SD age at onset, 39.8 +/- 7.3 years) of 1100 patients with PD.
  
  
  METHODS
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-Dong, Kangnam-Gu, Seoul 135-710, Korea.
authors.forename: Eun Joo
authors.initials: EJ
authors.lastname: Chung
authors.forename: Chang-Seok
authors.initials: CS
authors.lastname: Ki
authors.forename: Won Yong
authors.initials: WY
authors.lastname: Lee
authors.forename: In-Suk
authors.initials: IS
authors.lastname: Kim
authors.forename: Ji-Youn
authors.initials: JY
authors.lastname: Kim
mesh_terms: D000328:Adult; D017668:Age of Onset; D004409:Dyskinesia, Drug-Induced / Q000453:epidemiology / Q000235:genetics; D005260:Female; D006801:Humans; D007723:Korea / Q000453:epidemiology; D007980:Levodopa / Q000009:adverse effects / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010300:Parkinson Disease / Q000188:drug therapy / Q000453:epidemiology* / Q000235:genetics*; D011494:Protein Kinases / Q000235:genetics; D044767:Ubiquitin-Protein Ligases / Q000235:genetics; D000099202:PTEN-Induced Putative Kinase
chemical_list: D007980:Levodopa; D011494:Protein Kinases; D044767:Ubiquitin-Protein Ligases; D000099202:PTEN-Induced Putative Kinase; C111567:parkin protein