We describe three individuals from two families with a recessive inborn error of metabolism, characterized by megaloblastic anemia and/or pancytopenia, severe cerebral folate deficiency, and cerebral tetrahydrobiopterin deficiency due to a germline missense mutation in DHFR, resulting in profound enzyme deficiency.
Dihydrofolate reductase deficiency due to a homozygous DHFR mutation causes megaloblastic anemia and cerebral folate deficiency leading to severe neurologic disease.