A serine synthesis defect presenting with a Charcot-Marie-Tooth-like polyneuropathy.

Background: Serine synthesis defects, characterized by developmental delay and seizures, have been described in children.
Objective: To describe a case of serine synthesis defect due to 3-phosphoglycerate dehydrogenase deficiency in an adult with prominent chronic polyneuropathy.
Design: Case report.
Setting: Neurologic referral center.
Patient: A 31-year-old man with congenital cataracts, mild psychomotor retardation, slight cerebellar ataxia, and chronic axonal sensorimotor polyneuropathy.
Interventions: Electrophysiologic, metabolic, and genetic testing and treatment with oral L-serine.
Main Outcome Measures: Serine values in plasma and cerebrospinal fluid and clinical examination.
Results: Amino acid analysis showed low serine levels in plasma and cerebrospinal fluid, and genetic analysis revealed 2 heterozygous mutations in the PGDH gene. Treatment with high-dose serine resulted in normalization of plasma serine values and subjective functional improvement.
Conclusions: This case expands the phenotypic spectrum of 3-phosphoglycerate dehydrogenase deficiency. Plasma amino acid chromatography should be added to the list of investigations performed in patients with Charcot-Marie-Tooth–like polyneuropathy, especially if it is associated with psychomotor delay and congenital cataracts.