title: The Genetic Overlap Between Hair and Eye Color.
abstract: We identified the genetic variants for eye color by Genome-Wide Association Study (GWAS) in a Dutch Caucasian family-based population sample and examined the genetic correlation between hair and eye color using data from unrelated participants from the Netherlands Twin Register. With the Genome-wide Complex Trait Analysis software package, we found strong genetic correlations between various combinations of hair and eye colors. The strongest positive correlations were found for blue eyes with blond hair (0.87) and brown eyes with dark hair (0.71), whereas blue eyes with dark hair and brown eyes with blond hair showed the strongest negative correlations (-0.64 and -0.94, respectively). Red hair with green/hazel eyes showed the weakest correlation (-0.14). All analyses were corrected for age and sex, and we explored the effects of correcting for principal components (PCs) that represent ancestry and describe the genetic stratification of the Netherlands. When including the first three PCs as covariates, the genetic correlations between the phenotypes disappeared. This is not unexpected since hair and eye colors strongly indicate the ancestry of an individual. This makes it difficult to separate the effects of population stratification and the true genetic effects of variants on these particular phenotypes.
authors.affiliation: Netherlands Twin Register,Department of Biological Psychology,Vrije Universiteit,Amsterdam,the Netherlands.
authors.forename: Bochao D
authors.initials: BD
authors.lastname: Lin
authors.affiliation: Netherlands Twin Register,Department of Biological Psychology,Vrije Universiteit,Amsterdam,the Netherlands.
authors.forename: Gonneke
authors.initials: G
authors.lastname: Willemsen
authors.affiliation: Netherlands Twin Register,Department of Biological Psychology,Vrije Universiteit,Amsterdam,the Netherlands.
authors.forename: Abdel
authors.initials: A
authors.lastname: Abdellaoui
authors.affiliation: Netherlands Twin Register,Department of Biological Psychology,Vrije Universiteit,Amsterdam,the Netherlands.
authors.forename: Meike
authors.initials: M
authors.lastname: Bartels
authors.affiliation: Avera Institute for Human Genetics,Avera McKennan Hospital & University Health Center,Sioux Falls,South Dakota,USA.
authors.forename: Erik A
authors.initials: EA
authors.lastname: Ehli
authors.affiliation: Avera Institute for Human Genetics,Avera McKennan Hospital & University Health Center,Sioux Falls,South Dakota,USA.
authors.forename: Gareth E
authors.initials: GE
authors.lastname: Davies
authors.affiliation: Netherlands Twin Register,Department of Biological Psychology,Vrije Universiteit,Amsterdam,the Netherlands.
authors.forename: Dorret I
authors.initials: DI
authors.lastname: Boomsma
authors.affiliation: Netherlands Twin Register,Department of Biological Psychology,Vrije Universiteit,Amsterdam,the Netherlands.
authors.forename: Jouke J
authors.initials: JJ
authors.lastname: Hottenga
mesh_terms: D000328:Adult; D005127:Eye Color / Q000235:genetics*; D005260:Female; D005828:Genetics, Population; D055106:Genome-Wide Association Study; D006197:Hair / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D044465:White People
keywords: eye color; genetic correlation; hair color; physical characteristics; population stratification