were reported for the enrichment of MSNs and pyramidal cells (CA1) in AN [9]. Recently, more extensive cell type enrichment analysis was performed for 28 phenotypes using mouse gene expression from the entire central nervous system (CNS) [10]. In psychiatric disorders, enrichment was found for MSNs, cortical interneurons, striatal interneurons, neuroblasts, pyramidal cells (CA1 and SS) [10]. In neurological disorders, fewer cell types were identified and these were dissimilar across disorders [10]. These cell type enrichment analyses have mainly been performed using Linkage Disequilibrium Score Regression (LDSC) and/or Multi-marker Analysis of GenoMic Annotation (MAGMA). However, in this landmark and other studies, MAGMA versions <1.08 have been employed [8–10], of which it was recently reported that its SNP-level P value aggregation into gene-level P values might result in type-I errors [11]. In addition, cell type enrichment in SUDs and several other disorders, such as anxiety disorders, has to the best of our knowledge not been studied.
