In line with our aim to elucidate gene expression patterns in PKU, for the first time, we proposed NT2/D1-derived neurons as a novel model for the Phe-mediated neuronal effect and, also for the first time, pointed out the PREX1, LRP4, CDC42BPG, GPR50, PRMT8, RASGRF2, and CDH6 genes in the context of PKU. The gene discussed is PREX1; the disease is phenylketonuria.