PPIA and schizophrenia: BestKeeper suggested the same 3 genes (GAPDH, TFB1M and PPIA) should be used as reference genes in BA 9 and 44; using these reference genes meant there was no significant variation in levels of mRNA with diagnoses in BA 9 (Fig. 5e) but there were trends to lower levels of SNCA and NOL9 in BA 44 for people with schizophrenia (Fig. 5f).