title: Head injury, α-synuclein genetic variability and Parkinson's disease.
abstract: OBJECTIVE
  Head injury has been linked to Parkinson's disease (PD) in some but not all studies. Differences in the genetic and environmental susceptibility to PD between populations might be one explanation. The joint effects of head injuries and SNCA genetic variants were investigated.
  
  
  METHODS
  From 2001 to 2012, 561 incident idiopathic PD cases and 721 population controls from central California were enrolled. Subjects reported on head injuries throughout their lifetime and were assessed for genetic variability in the SNCA 5' region (D4S3481; Rep1) and 3' untranslated region (rs356165). In unconditional logistic regression models adjusted for confounders, interactions between head injuries and genetic risk variants were investigated.
  
  
  RESULTS
  Parkinson's disease risk in individuals with head injury who are carriers of at least one 263 bp allele in D4S3481 or rs356165 variants was 3-4.5-fold higher compared with non-carriers without head injuries. However, tests for interaction between head injury and SNCA D4S3481or rs356165 were not statistically significant.
  
  
  CONCLUSIONS
  Our study finds some evidence that head injury and D4S3481 or rs356165 variants jointly increase the risk of PD but little evidence of interaction.
authors.affiliation: Department of Health Care Management, College of Healthcare Administration and Management, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan.
authors.forename: P C
authors.initials: PC
authors.lastname: Lee
authors.forename: Y
authors.initials: Y
authors.lastname: Bordelon
authors.forename: J
authors.initials: J
authors.lastname: Bronstein
authors.forename: J S
authors.initials: JS
authors.lastname: Sinsheimer
authors.forename: M
authors.initials: M
authors.lastname: Farrer
authors.forename: B
authors.initials: B
authors.lastname: Ritz
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D006259:Craniocerebral Trauma / Q000150:complications / Q000235:genetics*; D005260:Female; D059647:Gene-Environment Interaction; D014644:Genetic Variation; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000209:etiology / Q000235:genetics*; D012307:Risk Factors; D051844:alpha-Synuclein / Q000235:genetics*
chemical_list: C497604:SNCA protein, human; D051844:alpha-Synuclein
keywords: Parkinson's disease; gene−environment interaction; head injury