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Vitamin B12 deficiency affects multiple systems, including hematologic, neurologic, dermatologic, and gastrointestinal.

Hereditary folate malabsorption (HFM, congenital folate malabsorption; OMIM#229050) is a rare, potentially treatable autosomal recessive disorder with multisystem involvement.1 It is caused by homozygous or compound heterozygous mutations in SLC46A1 resulting in loss of function of proton-coupled folate transporter (PCFT),2 required for intestinal absorption and transport of folate across choroid plexus.1,2 This leads to the deficiency of folate in serum and CSF, causing hematologic, immunologic, gastrointestinal, and neurologic manifestations.1 Neuroimaging shows intracranial calcification.3 Diagnosis is confirmed by impaired absorption of an oral folate load, low CSF folate concentration (even after correction of the serum folate concentration), or the identification of pathogenic variants in SLC46A1 on molecular genetic testing.1 We describe the clinical, imaging, biochemical, and genetic findings of a patient with HFM.