title: Factors influencing the development of early- or late-onset Parkinson's disease in a cohort of South African patients.
abstract: BACKGROUND
  Neurodegenerative disorders such as Parkinson's disease (PD) contribute significantly to global disease burden. PD can be categorised into early-onset PD (EOPD) with an age at onset (AAO) of ≤50 years and late-onset PD (LOPD) with an AAO of 50 years.
  
  
  OBJECTIVE
  To identify factors influencing EOPD and LOPD development in a group of patients in South Africa (SA).
  
  
  METHODS
  A total of 397 unrelated PD patients were recruited from the Movement Disorders Clinic at Tygerberg Hospital and via the Parkinson's Association of SA. Patient demographic and environmental data were recorded and associations with PD onset (EOPD v. LOPD) were analysed with a Pearson's Chi-squared test. The English- and Afrikaans-speaking (Afrikaner) white patients were analysed separately.
  
  
  RESULTS
  Logistic regression analysis showed that ethnicity (p<0.001) and family history (p=0.004) were independently associated with AAO of PD. Average AAO was younger in black, coloured and Afrikaner patients than English-speaking white patients. A positive family history of PD, seen in 31.1% of LOPD patients, was associated with a younger AAO in the study population.
  
  
  CONCLUSIONS
  These associations may be attributed to specific genetic and/or environmental risk factors that increase PD susceptibility and influence the clinical course of the disorder. More studies on PD in the unique SA populations are required to provide novel insights into mechanisms underlying this debilitating condition.
authors.affiliation: Division of Molecular Biology and Human Genetics, Stellenbosch University, Tygerberg, Western Cape, South Africa. celiavdm@sun.ac.za
authors.forename: Celia
authors.initials: C
authors.lastname: van der Merwe
authors.forename: William
authors.initials: W
authors.lastname: Haylett
authors.forename: Justin
authors.initials: J
authors.lastname: Harvey
authors.forename: Debbie
authors.initials: D
authors.lastname: Lombard
authors.forename: Soraya
authors.initials: S
authors.lastname: Bardien
authors.forename: Jonathan
authors.initials: J
authors.lastname: Carr
mesh_terms: D017668:Age of Onset; D015331:Cohort Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D016015:Logistic Models; D008297:Male; D010300:Parkinson Disease / Q000453:epidemiology* / Q000235:genetics; D010375:Pedigree; D013019:South Africa / Q000453:epidemiology