title: Evidence for a polygenic contribution to androgenetic alopecia.
abstract: BACKGROUND
  Male pattern baldness (androgenetic alopecia, AGA) is a highly heritable trait and the most common form of hair loss in humans. Eight genome-wide significant risk loci for AGA have been identified.
  
  
  OBJECTIVE
  To determine whether a polygenic component contributes to the genetic risk for AGA.
  
  
  METHODS
  This study used a German case-control sample for AGA, which comprised 581 severely affected patients and 617 controls, to determine the contribution of polygenic variance to AGA risk. The sample was divided evenly into discovery and test samples. An additive polygenic risk score was calculated from risk alleles with increasingly liberal P-values in the discovery dataset, which was then used to test for the enrichment of AGA risk score alleles in the independent test samples.
  
  
  RESULTS
  The polygenic score analysis provided significant evidence for a polygenic contribution to AGA where the amount of variance explained was 1·4-4·5%.
  
  
  CONCLUSIONS
  This study provides evidence for the specific contribution of a polygenic component to the overall heritable risk for AGA. To some degree, the polygenic architecture of AGA might reflect the complexity of the biological pathways involved. Further analyses and strategies that complement conventional genome-wide association studies are needed to identify these factors. These may include pathway-based analyses, the analysis of functional candidate genes and tests for epistatic effects with known loci.
authors.affiliation: Institute of Human Genetics, University of Bonn, Bonn, Germany; Department of Genomics, Life and Brain Centre, University of Bonn, Bonn, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Heilmann
authors.forename: F F
authors.initials: FF
authors.lastname: Brockschmidt
authors.forename: A M
authors.initials: AM
authors.lastname: Hillmer
authors.forename: S
authors.initials: S
authors.lastname: Hanneken
authors.forename: S
authors.initials: S
authors.lastname: Eigelshoven
authors.forename: K U
authors.initials: KU
authors.lastname: Ludwig
authors.forename: C
authors.initials: C
authors.lastname: Herold
authors.forename: E
authors.initials: E
authors.lastname: Mangold
authors.forename: T
authors.initials: T
authors.lastname: Becker
authors.forename: R
authors.initials: R
authors.lastname: Kruse
authors.forename: M
authors.initials: M
authors.lastname: Knapp
authors.forename: M M
authors.initials: MM
authors.lastname: Nöthen
mesh_terms: D000328:Adult; D000368:Aged; D000505:Alopecia / Q000235:genetics*; D016022:Case-Control Studies; D020022:Genetic Predisposition to Disease / Q000235:genetics; D055106:Genome-Wide Association Study; D006801:Humans; D008297:Male; D008875:Middle Aged; D020412:Multifactorial Inheritance / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*