PRODH and schizophrenia: The direct consequences of elevated proline for neurotransmission have been best demonstrated by work on the hyperprolinemic Prodh-null model.7, 8 In the presence of POX deficiency and elevated proline (peripheral and CNS), the mouse exhibits altered glutamate and dopamine signaling, including an enhancement of glutamatergic synaptic transmission, prefrontal dopamine transmission, and functional hyperdopaminergic responses.8 Genetic association studies have also implicated PRODH, not only in schizophrenia,13 but also in the etiology of endophenotypes associated with schizophrenia.14