title: Improved eye- and skin-color prediction based on 8 SNPs.
abstract: OBJECTIVE
  To improve the 7-plex system to predict eye and skin color by increasing precision and detailed phenotypic descriptions.
  
  
  METHODS
  Analysis of an eighth single nucleotide polymorphism (SNP), rs12896399 (SLC24A4), showed a statistically significant association with human eye color (P=0.007) but a rather poor strength of agreement (κ=0.063). This SNP was added to the 7-plex system (rs12913832 at HERC2, rs1545397 at OCA2, rs16891982 at SLC45A2, rs1426654 at SLC24A5, rs885479 at MC1R, rs6119471 at ASIP, and rs12203592 at IRF4). Further, the instruction guidelines on the interpretation of genotypes were changed to create a new 8-plex system. This was based on the analysis of an 803-sample training set of various populations. The newly developed 8-plex system can predict the eye colors brown, green, and blue, and skin colors light, not dark, and not light. It is superior to the 7-plex system with its additional ability to predict blue eye and light skin color.
  
  
  RESULTS
  The 8-plex system was tested on an additional 212 samples, the test set. Analysis showed that the number of positive descriptions for eye colors as being brown, green, or blue increased significantly (P=6.98e-15, z-score: -7.786). The error rate for eye-color prediction was low, at approximately 5%, while the skin color prediction showed no error in the test set (1% in training set).
  
  
  CONCLUSIONS
  We can conclude that the new 8-plex system for the prediction of eye and skin color substantially enhances its former version.
authors.affiliation: Office of Chief Medical Examiner, Department of Forensic Biology, 421East 26th Street, Box 12-79, New York, NY 10016, USA.
authors.forename: Katie L
authors.initials: KL
authors.lastname: Hart
authors.forename: Shey L
authors.initials: SL
authors.lastname: Kimura
authors.forename: Vladimir
authors.initials: V
authors.lastname: Mushailov
authors.forename: Zoran M
authors.initials: ZM
authors.lastname: Budimlija
authors.forename: Mechthild
authors.initials: M
authors.lastname: Prinz
authors.forename: Elisa
authors.initials: E
authors.lastname: Wurmbach
mesh_terms: D054366:Agouti Signaling Protein / Q000235:genetics; D000951:Antigens, Neoplasm / Q000235:genetics; D017920:Antiporters / Q000235:genetics; D005127:Eye Color / Q000235:genetics*; D005838:Genotype; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics; D006801:Humans; D050835:Interferon Regulatory Factors / Q000235:genetics; D026901:Membrane Transport Proteins / Q000235:genetics; D020641:Polymorphism, Single Nucleotide; D044102:Receptor, Melanocortin, Type 1 / Q000235:genetics; D012880:Skin Pigmentation / Q000235:genetics*; D044767:Ubiquitin-Protein Ligases; D044465:White People / Q000235:genetics*; D000099218:Interferon Regulatory Factor-4
chemical_list: D054366:Agouti Signaling Protein; D000951:Antigens, Neoplasm; D017920:Antiporters; D020662:Guanine Nucleotide Exchange Factors; D050835:Interferon Regulatory Factors; D026901:Membrane Transport Proteins; D044102:Receptor, Melanocortin, Type 1; D044767:Ubiquitin-Protein Ligases; D000099218:Interferon Regulatory Factor-4; C515182:ASIP protein, human; C489600:OCA2 protein, human; C470570:SLC24A4 protein, human; C506584:SLC24A5 protein, human; C510061:SLC45A2 protein, human; C118566:HERC2 protein, human