Iritani et al. (1999) reported that calbindin-D28K positive cells are distributed abnormally in the prefrontal cortex (Brodmann area 9). Cajal–Retzius cells, which produce reelin signals, are more numerous in the lower third of layer I in schizophrenia patients (Kalus et al., 1997). Again, since netrin-1 is expressed in layer I and IZ, and involved in interneuron migration during the gestation stage (Figure 2), these abnormal distributions may explain the correlation between psychiatric disorders associated with Netrin-1 and DCC mutations (Vosberg et al., 2020). The gene discussed is DCC; the disease is psychiatric disorder.