Phosphoglycerate dehydrogenase deficiency is an autosomal recessive disorder of serine biosynthesis. It is characterized by microcephaly, psychomotor retardation and seizure. Different types were described based on the severity and age of onset. Without prompt treatment, seizures may progress to tonic-clonic seizures, which involve a loss of consciousness and muscle rigidity. Patients can be treated with a combination of L-serine and glycine.