Synapsin and VGAT (Fig. 2E–F) and exhibit similar intrinsic membrane properties (Supplemental Fig. 2D–E) as well as sIPSC and AP properties in both genotypes (Supplemental Figs. 2F–G, Supplemental Figs. 3A–C).The densities and sizes of synapses were also not significantly different between genotypes (Supplemental Fig. 2H–I). To examine the overall homogeneity as well as to demonstrate similar maturation stages of isogenic iNs we performed qPCR against several diagnostic mRNA targets (Summary is at Supplemental Table 1, Supplemental Fig. 4). We measured the expression levels of all four classes of opioid receptors, various subunits of GABAA and GABAB receptors, and classic markers to identify specific subclasses of GABAergic neurons. We found no significant differences between mRNA levels (with the exception of the mRNA encoding the Kappa Opioid Receptor, OPRK1) between N40- and D40-containing iNs. To further validate our qPCR data, we also performed IHC against 3 of the major GABAergic neuronal subtypes: parvalbumin (PV), calbinidin-1 (Calb1), and somatostatin (SST). Consistent with the qPCR we observed a strong SST signal in both genotypes (Supplemental Fig. 4A). These data illustrate that the N40D SNP does not alter synaptogenesis and functional maturation as well as the patterning of isogenic human neurons. These data further suggest
