To optimize detection of genetic associations, we can, in addition to increasing sample sizes, invest in harmonizing the phenotype and explore options for multivariate analyses as EEG features are inherently multidimensional. In this article, we highlight our efforts to extract harmonized EEG features, the steps we have taken, and the future steps we would like to take. Equally important is the harmonized analyses of the genetic information. For genotyping, imputation, and quality control of genetic data, we closely follow the recommendations and pipelines from our colleagues in the ENIGMA Genetics working group described online (http://enigma.ini.usc.edu/protocols/genetics‐protocols/) (Grasby et al., 2018; Hibar et al., 2015; Stein et al., 2012). These guidelines and protocols, which we consider just as important as high‐quality neurophysiological biomarker extraction, will not be further covered in the current article, since there is a large specialized body of literature describing QC and methodology for genetic association, genetic meta‐analysis, and polygenic score calculation (e.g., Lam et al., 2020; Marees et al., 2018; Privé et al., 2020; Ni et al., 2021).
