Hydrocephalus presented as the prominent symptom of severe 5,10-methylenetetrahydrofolate reductase deficiency in an infant

Hyperhomocysteinemia due to the deficiency of 5,10-Methylenetetrahydrofolate reductase (5,10-methyl THR reductase or MTHFR) is an autosomal recessive rare disease caused by defects in MTHFR gene. The clinical manifestations of this disorder are heterogeneous, ranging from asymptomatic to severe neurological disorders. However, hydrocephalus has been seldom reported in patients with MTHFR deficiency. Here, we report a severe infantile case of 5,10-methyl THF reductase deficiency in China, whose main manifestation is hydrocephalus. We also studied the clinical course and the genotype of the patient.