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Phenotypic description and functional characterization of the mitochondrial disease associated with the SFXN4 gene

Sarah Courtois1, Chloé Angelini2, Juliette Preud'homme3

  • 1INSERM U1211, Rare diseases: genetics and metabolism (MRGM), University of Bordeaux, France; CRMSB - UMR 5536 - CNRS, Centre de Résonance Magnétique des Systèmes Biologiques, University of Bordeaux, France.

Mitochondrion
|February 19, 2026
PubMed

Insights

Pathogenic variants in the Sideroflexin 4 (SFXN4) gene are linked to intellectual disability and macrocytic anemia. This study identifies a new patient with SFXN4 variants, presenting with sideroblastic macrocytosis and mitochondrial complex I deficiency.

Area of Science:

  • Mitochondrial biology
  • Human genetics
  • Biochemistry

Background:

  • Sideroflexin 4 (SFXN4) is a mitochondrial inner membrane protein.
  • SFXN4 is implicated in iron-sulfur cluster biogenesis.
  • Previously, pathogenic SFXN4 variants were reported in only three patients with intellectual disability and macrocytic anemia.

Purpose of the Study:

  • To describe a novel patient with pathogenic SFXN4 variants.
  • To characterize the clinical and molecular phenotype associated with these variants.

Main Methods:

  • Clinical case description
  • Genetic variant analysis
  • Mitochondrial function assessment (Complex I deficiency)

Main Results:

  • A patient with pathogenic SFXN4 variants was identified.
  • The patient presented with non-anaemic sideroblastic macrocytosis.
  • Mitochondrial complex I deficiency was detected in the patient.

Conclusions:

  • Pathogenic SFXN4 variants can cause a spectrum of phenotypes beyond anemia.
  • SFXN4 deficiency is associated with mitochondrial dysfunction, specifically complex I deficiency.
  • This case expands the known clinical spectrum of SFXN4-related disorders.
Keywords:
MacrocytosisMitochondrial diseaseSFXN4

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