NRG1 and schizophrenia: Notably, although no line-related differences in DA D2 receptors have been demonstrated compared to the high-PPI line, the low-PPI line displays lower neuregulin-1 (Ngr1 gene) methylation (suggesting increased neuregulin-1 levels) in brain regions considered to be relevant in schizophrenia, such as the medial prefrontal cortex, the nucleus accumbens, and the ventral hippocampus [62].