Overall, there was a significant correlation between reduced neuronal PV mRNA expression and a decreased density of GAD₆₇ mRNA-positive neurons in those with schizophrenia. There was a strong correlation when comparing the within-pair differences in GAD₆₇ mRNA-positive neuron density and the in grain density per PV mRNA-positive neuron. There was no correlation in the differences of GAD₆₇ mRNA-positive neuron density and in PV mRNA-positive neuron density. There was also no significant correlation in the differences of GAD₆₇ mRNA-positive neurons and CR mRNA-positive neuron density or grain density per CR mRNA-positive neuron. GAD₆₇ mRNA signals were undetectable in many (about 45%) PV mRNA-positive grain clusters - the amount of these neurons with undetectable signals was 4.5 times greater in those with schizophrenia. These results suggest that GAD₆₇ mRNA expression is deficit in schizophrenia patients only in a selective subclass of PV-containing GABA neurons in the prefrontal cortex