a, b Diagrams of the pedigree including a pair of monozygotic twins discordant for SZ. DT2_A and DT3_A, affected twins; DT2_U and DT3_U, unaffected twins. c Gene expression levels of GABAergic synapse-related genes from bulk RNA-seq analysis. Representative genes encoding GABA receptor subunits and ion channels are shown. A affected twin, U unaffected twin. Welch’s t test: *p < 0.05; **p < 0.01. See also Fig. S9.