title: Vitamin D receptor gene polymorphisms and Parkinson's disease in a population with high ultraviolet radiation exposure.
abstract: BACKGROUND
  A high prevalence of vitamin D deficiency has been reported in Parkinson's disease (PD). Epidemiologic studies examining variability in genes involved in vitamin D metabolism have not taken into account level of exposure to ultraviolet radiation (UVR). We examined whether exposure to UVR (as a surrogate for vitamin D levels) and variations in the vitamin D receptor gene (VDR) are associated with PD.
  
  
  METHODS
  Within a geographical information system (GIS) we linked participants' geocoded residential address data to ground level UV data to estimate historical exposure to UVR. Six SNPs in VDR were genotyped in non-Hispanic Caucasian subjects.
  
  
  RESULTS
  Average lifetime UVR exposure levels were >5000 Wh/m(2), which was higher than levels for populations in previous studies, and UVR exposure did not differ between cases and controls. Homozygotes for the rs731236 TT (major allele) genotype had a 31% lower risk of PD risk (OR=0.69; 95% CI=0.49, 0.98; p=0.04 for TT vs. TC+CC). The rs7975232 GG (minor allele) genotype was also associated with decreased risk of PD (OR=0.63; 95% CI=0.42, 0.93; p=0.02 for GG vs. TG+TT). The association between PD risk and a third locus, rs1544410 (BsmI), was not statistically significant after adjustment for covariates, although there was a trend for lower risk with the GG genotype.
  
  
  CONCLUSIONS
  This study provides initial evidence that VDR polymorphisms may modulate risk of PD in a population highly exposed to UVR throughout lifetime.
authors.affiliation: Center for Nutrition, Healthy Lifestyles & Disease Prevention, School of Public Health, Loma Linda University, United States. Electronic address: ngatto@llu.edu.
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Gatto
authors.affiliation: Department of Human Genetics, UCLA, United States; Department of Biomathematics, UCLA, United States; Department of Biostatistics, UCLA, United States.
authors.forename: Janet S
authors.initials: JS
authors.lastname: Sinsheimer
authors.affiliation: Department of Preventive Medicine, University of Southern California, United States.
authors.forename: Myles
authors.initials: M
authors.lastname: Cockburn
authors.affiliation: Department of Preventive Medicine, University of Southern California, United States.
authors.forename: Loraine A
authors.initials: LA
authors.lastname: Escobedo
authors.affiliation: Department of Neurology, UCLA, United States.
authors.forename: Yvette
authors.initials: Y
authors.lastname: Bordelon
authors.affiliation: Department of Epidemiology, UCLA, United States; Department of Environmental Health Sciences, UCLA, United States; Department of Neurology, UCLA, United States.
authors.forename: Beate
authors.initials: B
authors.lastname: Ritz
mesh_terms: D000328:Adult; D000368:Aged; D000483:Alleles; D016022:Case-Control Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006720:Homozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D015995:Prevalence; D000069079:Radiation Exposure / Q000032:analysis*; D018167:Receptors, Calcitriol / Q000235:genetics*; D012307:Risk Factors; D014466:Ultraviolet Rays; D044465:White People
chemical_list: D018167:Receptors, Calcitriol
keywords: ApaI; Parkinson's disease; TaqI; Ultraviolet radiation; Vitamin D; Vitamin D receptor gene polymorphisms