Genomic DNA was prepared from whole blood according to standard procedures. For all samples, DNA concentrations were quantified in triplicate measurements by Picogreends DNA Quantitation Kit (www.invitrogen.com) and normalized to 50 ng/ul at the CIMH, Molecular Genetics Laboratory. For the GWAS, all samples were genotyped individually using Human Hap 550 BeadChips (Illumina, Inc., San Diego, CA, USA). The patient and the PopGen and KORA samples were genotyped at Illumina Inc. and the HNR sample was genotyped at the Department of Genomics at the Life & BrainCenter, University of Bonn. Genotyping of the follow-up sample was performed by primer extension reaction chemistry with MALDI-TOF mass spectrometry using the iPLEX® Assay (Sequenom, San Diego, USA) at the Life & BrainCenter, University of Bonn. Genotyping results were imported into a central computer system for statistical analysis.
