long storage times before cryopreservation. Furthermore, the Seattle cohort was collected in three independent centers, giving rise to differences among samples regarding tissue acquisition and storage protocols, criteria for RNA quality, etc. Another significant influential factor in the Seattle study was ethnicity,16 in contrast to our study in which no influence was detected using population stratification methods. Finally, the availability of medical information was also different in the two studies. Whereas the former study used imputation methods to complete large parts of missing information, medical documentation for the Stuttgart liver samples were almost complete and comprised a larger number of parameters.
