Of the follow-up groups, the Norwegian sample was genotyped at the University of Oslo using the Affymetrix 6.0 chip (Santa Clara, CA, USA). The remaining groups were single-marker genotyped at deCODE Genetics using Centaurus assays (Nanogen, San Diego, CA, USA). Yield for rs1344706 was at least 94% in both cases and controls of all study groups and, in the controls of each group, rs1344706 did not deviate significantly from the Hardy–Weinberg equilibrium (P > 0.01).
