according to manufacturer’s instructions. For quality controls, each plate contained at least eight water controls and 22 duplicate samples. PCR reactions were performed in a total reaction volume of 5μl using 20ng of genomic DNA obtained by blood draw (Kettunen et al, Nat Genet 2012). The alleles were automatically called by Sequenom’s Mass ARRAY Typer Analyzer software and verified by two independent persons. Further marker-specific quality controls included a call rate >80% and a Hardy-Weinberg equilibrium (HWE) p-value >0.01 (estimated using unrelated individuals). Mendelian errors were excluded using PedCheck (O’Connell & Weeks, 1998).
