Biallelic NDUFA4 Deletion Causes Mitochondrial Complex IV Deficiency in a Patient with Leigh Syndrome

Genes (Basel). 2024 Apr 17;15(4):500. doi: 10.3390/genes15040500.


Oxidative phosphorylation involves a complex multi-enzymatic mitochondrial machinery critical for proper functioning of the cell, and defects herein cause a wide range of diseases called "primary mitochondrial disorders" (PMDs). Mutations in about 400 nuclear and 37 mitochondrial genes have been documented to cause PMDs, which have an estimated birth prevalence of 1:5000. Here, we describe a 4-year-old female presenting from early childhood with psychomotor delay and white matter signal changes affecting several brain regions, including the brainstem, in addition to lactic and phytanic acidosis, compatible with Leigh syndrome, a genetically heterogeneous subgroup of PMDs. Whole genome sequencing of the family trio identified a homozygous 12.9 Kb deletion, entirely overlapping the NDUFA4 gene. Sanger sequencing of the breakpoints revealed that the genomic rearrangement was likely triggered by Alu elements flanking the gene. NDUFA4 encodes for a subunit of the respiratory chain Complex IV, whose activity was significantly reduced in the patient's fibroblasts. In one family, dysfunction of NDUFA4 was previously documented as causing mitochondrial Complex IV deficiency nuclear type 21 (MC4DN21, OMIM 619065), a relatively mild form of Leigh syndrome. Our finding confirms the loss of NDUFA4 function as an ultra-rare cause of Complex IV defect, clinically presenting as Leigh syndrome.

Keywords: Alu element; COX; Complex IV; Leigh syndrome; NDUFA4/COXFA4; WGS; encephalopathy; structural variant (SV).

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Child, Preschool
  • Electron Transport Complex I*
  • Electron Transport Complex IV / genetics
  • Female
  • Humans
  • Leigh Disease* / genetics
  • Leigh Disease* / pathology
  • Mitochondrial Diseases / genetics
  • Mitochondrial Diseases / pathology
  • Pedigree
  • Sequence Deletion


  • Electron Transport Complex IV
  • NDUFS4 protein, human
  • Electron Transport Complex I

Grants and funding

D.M. was supported by Anders Jahres Fond til Vitenskapens Fremme. E.F. was supported by the Nasjonal Kompetansetjeneste for Sjeldne Diagnoser (Norwegian National Advisory Unit on Rare Disorders), Norway.