An additional limitation was that we examined only three genes encoding GABAA receptor subunits (GABRA1, GABRG2, and GABRD). These genes were selected because their expression is reliably detected in our iPSC-derived neural culture system and because prior studies reported differences in their expression following alcohol exposure (for review, see (Kumar et al. 2009). We did not examine the effects of alcohol on the expression of GABAA subunit-encoding genes located on chromosome 4 due to our prior observation of large basal expression differences of genes within this cluster among iPSC-derived neural cell lines (Lieberman et al. 2015). The variability in expression of chromosome 4 GABA genes among iPSC lines (Lieberman et al. 2015), with very low to undetectable levels in 40% of lines, was an unforeseen limitation of the model system that prevented us from examining these genes of interest in the current study.
