Serine racemase (SRR) is a pyridoxal phosphate-dependent enzyme that catalyzes the conversion of L-serine to D-serine 1. D-serine functions as a critical coagonist with glutamate at NMDA receptors in the forebrain, where it binds to the NR1 channel subunit to enable receptor activation 1. The enzyme operates through a reversible racemization mechanism and also possesses dehydratase activity toward both L-serine and D-serine substrates. SRR is predominantly localized to neuronal cell bodies and the cytosol, where it forms homodimers and interacts with PDZ domain-containing proteins. Genetically, SRR represents one of approximately two dozen schizophrenia risk genes affecting NMDA receptor function 1. In animal models, srr gene inactivation results in ~90% loss of endogenous D-serine and ~70% reduction in NMDA receptor function, producing schizophrenia-like phenotypes including cortical atrophy, synaptic spine loss, and cognitive impairments 1. Additionally, intronic SRR variants modulate expression of the neighboring SMG6 gene; the protective GG genotype at rs4523957 decreases SMG6 promoter activity and reduces temporal lobe epilepsy susceptibility and seizure severity 2. These findings implicate SRR-dependent D-serine synthesis in glutamatergic neurotransmission and reveal its relevance to neuropsychiatric and neurological diseases involving NMDA receptor hypofunction.