Impact of folate therapy on combined immunodeficiency secondary to hereditary folate malabsorption

Area of Science:

• Immunology
• Genetics
• Pediatrics

Background:

• Hereditary folate malabsorption (HFM) is a rare autosomal recessive disorder characterized by impaired folate absorption.
• Severe folate deficiency in HFM can lead to significant health complications, including immunodeficiency.

Observation:

• A female infant with HFM presented with severe Pneumocystis pneumonia, indicating a profound immune defect.
• The patient exhibited a combined immunodeficiency characterized by impaired T cell proliferation, pan-hypogammaglobulinemia, and an altered pro-inflammatory cytokine profile.

Findings:

• Genetic analysis revealed two novel mutations in the SLC46A1 gene, confirming a compound heterozygous state for HFM.
• Parenteral folate therapy led to complete recovery of the patient's immunological and neurophysiological status.
• The recovery of the immunological profile showed significant variability in its time course.

Implications:

• HFM should be recognized as a distinct and treatable form of primary immunodeficiency.
• Early diagnosis and intervention with folate replacement are crucial for managing HFM and preventing severe complications.
• Understanding the immunological phenotype and recovery patterns in HFM provides insights into folate's role in immune function.