MOCS3 and Encephalopathy: Four different genes are involved in Molybdenum cofactor biosynthesis: MOCS1, MOCS2, MOCS3, and GEPH. The classical form manifests in the neonatal period with severe encephalopathy, including intractable seizures, MRI changes that resemble hypoxic‐ischemic injury, microcephaly, and early death.