Post-mortem tissue homogenates of PFC grey matter (DLPFC, that is, BA46/9 in postnatal samples and the corresponding region of PFC in fetal samples) were obtained from all subjects (n = 269 after all exclusion criteria). Total RNA was extracted from ~100 mg of tissue using the RNeasy kit (Qiagen) according to the manufacturer’s protocol. Samples with RNA integrity number (RIN) <5 were excluded. 500 ng of each total RNA sample was reverse transcribed with an oligo dT-T7 and amplified (T7) using the Ambion MessageAmp II kit (catalogue no. 1753, Ambion). The generated aminoallyl UTP-labelled antisense RNAs (aRNAs) were then coupled with Cy3 mono NHS ester CyDye from GE Healthcare. Reference RNA was pooled from all samples and was treated identically to sample RNAs, but was labelled with the Cy5 fluorescent dye. Two-colour custom-spotted oligonucleotide microarrays from the NHGRI microarray core facility using the Illumina Oligoset (HEEBO7) of 49,152 70-mer probes were used. After purification, the labelled aRNAs are hybridized overnight to the oligo arrays in 53 SSC, 25% formamide and 0.2% SDS buffer at 45 °C using Maui Mixer FL
