C4A and schizophrenia: Phosphorus magnetic resonance spectroscopy in adult‐onset schizophrenia patients with high C4A gene copy numbers detected increased neuropil contraction in the prefrontal and parietal regions, whereas adolescent‐onset patients with high C4A gene copy numbers showed increased neuropil contraction in the prefrontal cortex and thalamus (Prasad et al., 2018).