Note: a that this varying was Blonde tresses + blue-eyes in the 1908 data and you can Blonde tresses + blue/grey sight about 2004 studies.

Measures

, Site van Beijsterveldt, Groen-Blokhuis, Hottenga, Franic, datingranking.net/it/incontri-bhm/ Hudziak and Lamb 2013; Willemsen et al., Resource Willemsen, Vink, Abdellaoui, den Braber, van Beek and you can Draisma 2013) was in fact included in this research in line with the exposure off notice-claimed studies to your absolute tresses and eye colour and also the exposure out-of genotype study to your an Illumina 370, 660, 1M otherwise Affymetrix Perlegen-5.0, or 6.0 program. There were 7,063 genotyped Dutch-origins people, clustered from inside the step three,407 family which have data toward attention color, and you will six,965 genotyped individuals got research for the one another tresses and you can eye color. Towards the genetic association study regarding eyes colour (select Supplementary point) every studies were reviewed. Having bivariate hereditary analyses from inside the GCTA, the unrelated citizens were selected, centered on an inherited relatedness matrix (GRM) cut-off 0.025 (Yang ainsi que al., Source Yang, Lee, Goddard and you may Visscher 2011). This remaining step three,619 people with the bivariate analyses, having a hereditary relatedness comparable to lower than third or 4th relative.

, Source Willemsen, Vink, Abdellaoui, den Braber, van Beek and Draisma 2013). Mature users stated their particular natural hair colour in one regarding five choice: ‘fair/blond’, ‘hazel’, ‘red/auburn’, ‘black brown’, and you can ‘black’ and you can eyes color which have certainly about three choices: ‘blue/gray’, ‘green/hazel’ and you will ‘brown’. A comparable concerns to your eyes colour and you may locks colour was in fact replied by adolescent (14- to help you 18-year-old) twins once they accomplished the Dutch Health insurance and Choices Survey for the 2005 or 2006 (van Beijsterveldt ainsi que al., Resource van Beijsterveldt, Groen-Blokhuis, Hottenga, Franic, Hudziak and Mutton 2013). Toward mathematical analyses, i mutual this new black, light brown, and you will brownish locks color to help you ‘dark’, while the merely hardly any someone claimed a black hair colour (Lin mais aussi al., Site Lin, Mbarek, Willemsen, Dolan, Fedko and you will Abdellaoui 2015). Authored advised consent try obtained from every members.

Many years, gender, sheer locks, and you can attention colour were obtained from Mature NTR questionnaire seven, which was accumulated in 2004 (Willemsen et al

DNA extraction, purification, and genotype calling of the samples were performed at various points in time following the manufacturer’s protocols and genotype calling programs (Lin et al., Reference Lin, Mbarek, Willemsen, Dolan, Fedko and Abdellaoui 2015). For each platform, the individual SNPs were remapped on the build 37 (HG19), ALL 1000 Genomes Phase 1 imputation reference dataset (Auton et al., Reference Auton, Brooks, Durbin, Garrison, Kang and Korbel 2015). SNPs that failed unique mapping and SNPs with an allele frequency difference over 0.20 with the reference data were removed. SNPs with a minor allele frequency (MAF) < 0.01 were also removed, as well as SNPs that were out of Hardy–Weinberg Equilibrium (HWE) with p < 10 ?5 . The platform data were then merged into a single genotype set and the above SNP QC filters were reapplied. Samples were excluded from the data when their DNA was discordant with their expected sex or IBD status, the genotype missing rate was above 10%, the Plink F-inbreeding value was either larger than 0.10 or smaller than ?0.10, or they were an ethnic outlier based on EIGENSTRAT PCs calculated from the 1000G imputed data (Auton et al., Reference Auton, Brooks, Durbin, Garrison, Kang and Korbel 2015). Phasing of the samples and imputing cross-missing platform SNPs was done with MACH 1 (Li Abecasis, Reference Li and Abecasis 2006). The phased data were then imputed with MINIMAC to the 1000G reference. After imputation, SNPs were filtered, based on Mendelian error rate (>2%), a R 2 imputation quality value of <0.80, MAF <0.01 and a difference of more than 0.15 between the allele frequency and the reference (Howie et al., Reference Howie, Fuchsberger, Stephens, ). We tested the effect of different platforms and removed SNPs showing platform effects. This was done by defining individuals on a specific platform as cases and the others as controls. If the allelic association between the specific platform allele frequency and the other platform's allele frequency was significant (p < 10 ?5 ) SNPs were removed. This left 5,987,253 SNPs, which were all used to construct a GRM.