title: An ecological correlation study of late age-related macular degeneration and the complement factor H Y402H polymorphism.
abstract: OBJECTIVE
  To investigate whether variation in the distribution of the risk allele frequency of the Y402H single-nucleotide polymorphism (SNP) across various ethnicities and geographic regions reflects differences in the prevalence of late age-related macular degeneration (AMD) in those ethnicities.
  
  
  METHODS
  Published data were obtained via a systematic search. Study samples were grouped into clusters by ethnicity and geographic location and the Spearman correlation coefficient of the prevalence of late AMD and risk allele frequencies was calculated across clusters.
  
  
  RESULTS
  Across all ethnicities, AMD prevalence was seen to increase with age. Populations of European descent had both higher risk allele frequencies and prevalence of late AMD than did Japanese, Chinese, and Hispanic descendants. Results for African descendants were anomalous: although allele frequency was similar to that in European populations, the age-specific prevalence of late AMD was considerably lower. The correlation coefficient for the association between allele frequency and AMD prevalence was 0.40 (95% confidence interval [CI] = -0.36 to 0.84, P = 0.28) in all populations combined and 0.71 (95% CI = 0.02-0.94, P = 0.04) when people of African descent were excluded.
  
  
  CONCLUSIONS
  Evidence was found at the population level to support a positive association between the Y204H risk allele and the prevalence of AMD after exclusion of studies undertaken on persons of African ancestry. Data in African, Middle Eastern, and South American populations are needed to provide a better understanding of the association of late AMD genetic risk across ethnicities.
authors.affiliation: Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom. aletta.nonyane@lshtm.ac.uk
authors.forename: Bareng A S
authors.initials: BA
authors.lastname: Nonyane
authors.forename: Dorothea
authors.initials: D
authors.lastname: Nitsch
authors.forename: John C
authors.initials: JC
authors.lastname: Whittaker
authors.forename: Reecha
authors.initials: R
authors.lastname: Sofat
authors.forename: Liam
authors.initials: L
authors.lastname: Smeeth
authors.forename: Usha
authors.initials: U
authors.lastname: Chakravarthy
authors.forename: Astrid E
authors.initials: AE
authors.lastname: Fletcher
mesh_terms: D000368:Aged; D017242:Complement Factor H / Q000235:genetics; D005006:Ethnicity; D005787:Gene Frequency; D005843:Geography; D006801:Humans; D008268:Macular Degeneration / Q000208:ethnology* / Q000235:genetics*; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D015995:Prevalence; D018570:Risk Assessment
chemical_list: C493495:CFH protein, human; D017242:Complement Factor H