On this page
NDUFS4
NADH:ubiquinone oxidoreductase subunit S4
NDUFS4 is located on the long (q) arm of chromosome 5, at band 5q11.2. Arm ratio per GRCh38 - banding schematic.
Explore chromosome 5 in the library →Available at Jeen Health
Clinical tests that include this
Overview
NDUFS4 encodes NADH:ubiquinone oxidoreductase subunit S4, a component of mitochondrial complex I. This enzyme complex sits within the inner mitochondrial membrane and catalyses the first step of oxidative phosphorylation, transferring electrons from NADH to ubiquinone whilst pumping protons across the membrane. The energy gradient created by this process ultimately drives ATP synthesis, the primary energy currency of cells.
Disease-causing NDUFS4 mutations disrupt the formation and activity of complex I, resulting in deficient ATP production and accumulation of reactive oxygen species. These metabolic disturbances particularly affect tissues with high energy demands, including the brain, leading to the characteristic neurological features observed in affected individuals. NDUFS4-related conditions follow an autosomal recessive inheritance pattern.
What the gene does
The NDUFS4 protein functions as an accessory subunit of mitochondrial complex I, contributing to the structural integrity and catalytic efficiency of this large enzyme assembly. The encoded protein is positioned within the matrix arm, where it helps coordinate electron transfer events during oxidative phosphorylation.
This protein supports the oxidation of NADH, produced during glycolysis and the citric acid cycle, facilitating electron passage through a chain of iron-sulphur clusters to the terminal electron acceptor, ubiquinone. The coupled proton translocation across the inner mitochondrial membrane establishes the electrochemical gradient required for ATP synthase activity. Research suggests NDUFS4 plays a particularly important role in maintaining complex I stability during assembly, with its absence leading to accumulation of incomplete subcomplexes.
Cells harbouring NDUFS4 deficiency exhibit reduced complex I activity, decreased oxygen consumption, and compensatory upregulation of glycolysis. The resulting metabolic dysfunction generates oxidative stress and impairs cellular processes that depend on efficient ATP generation, particularly affecting neurons and other high-energy tissues.
Video: Genetics 101
Chromosome location
NDUFS4 resides on the long arm of chromosome 5 at position 5q11.2. The gene spans a relatively compact genomic region and comprises six exons encoding a 175-amino-acid protein. This chromosomal location places NDUFS4 within a region containing several other genes involved in diverse cellular processes, though no specific structural features of the locus have been associated with the gene's pathogenicity.
Protein structure
The NDUFS4 protein comprises 175 amino acids forming a compact subunit within the matrix arm of complex I. Structural studies indicate that NDUFS4 adopts a globular fold that interfaces with neighbouring core subunits, contributing to the architecture surrounding the electron transfer chain. The protein contains a disordered region spanning amino acids 151 through 175 at its C-terminus, which may provide flexibility important for protein-protein interactions or regulatory modifications. This intrinsically unstructured segment contrasts with the more ordered N-terminal and central domains that participate directly in complex I assembly and stabilisation.
Key variants
Pathogenic variants in NDUFS4 predominantly include nonsense, frameshift, and missense changes that compromise protein function or stability. Loss-of-function variants typically result in absent or severely reduced NDUFS4 protein levels, whilst missense substitutions may disrupt critical interactions within the complex I assembly. The spectrum of reported variants reflects the gene's essential role in mitochondrial respiration, with most pathogenic changes leading to profound complex I deficiency.
Sample of pathogenic variants
10 pathogenic / likely-pathogenic variants from ClinVar, ranked by review status (expert-panel-reviewed first). This is a sample; recurrent founder variants in a specific population may not appear here - see the full ClinVar listing via the link above.
| Variant (HGVS) | Protein change | Classification | Evidence | Associated condition |
|---|---|---|---|---|
c.178-2A>G | - | Pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 1 |
c.221del | p.Thr74fs | Pathogenic/Likely pathogenic | ★★☆☆ | Leigh syndrome |
c.291del | p.Lys96_Trp97insTer | Pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 1 |
c.316C>T | p.Arg106Ter | Pathogenic/Likely pathogenic | ★★☆☆ | NDUFS4-related disorders |
c.319_322del | p.Trp107fs | Pathogenic/Likely pathogenic | ★★☆☆ | Inborn genetic diseases |
c.350+1G>A | - | Pathogenic/Likely pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 1 |
c.355G>C | p.Asp119His | Pathogenic/Likely pathogenic | ★★☆☆ | Mitochondrial complex I deficiency |
c.393dup | p.Glu132fs | Pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 1 |
c.462del | p.Lys154fs | Pathogenic | ★★☆☆ | NDUFS4-related disorders |
c.99-1G>A | - | Pathogenic | ★★☆☆ | Mitochondrial disease |
Evidence stars indicate ClinVar review status. Individual variant interpretation should always be performed by a qualified clinical laboratory - many variants remain classified as Variants of Uncertain Significance (VUS) pending more research.
Associated conditions
Biallelic pathogenic variants in NDUFS4 cause Leigh syndrome, a progressive neurodegenerative disorder characterised by symmetric lesions in the basal ganglia and brainstem. Affected individuals typically present in infancy or early childhood with developmental regression, hypotonia, feeding difficulties, and respiratory abnormalities. The condition demonstrates variable severity, though most cases follow a progressive course affecting motor function, cognition, and metabolic stability. Leigh syndrome arising from NDUFS4 variants represents one form of mitochondrial complex I deficiency, a group of disorders unified by impaired cellular energy metabolism.
Inheritance pattern
Conditions caused by pathogenic NDUFS4 variants typically follow autosomal recessive inheritance.
When both parents are carriers, each child has a 25% chance of being affected, 50% of being a carrier, and 25% of being unaffected.
UK clinical status
NDUFS4 holds green (high-evidence) status across multiple NHS Genomic Medicine Service gene panels, reflecting its well-established role in paediatric neurological and metabolic disease. The gene appears on panels including Mitochondrial disorders, Mitochondrial disorder with complex I deficiency, Intellectual disability, Early onset or syndromic epilepsy, and Childhood onset dystonia, chorea or related movement disorder. Additional memberships include the Inherited white matter disorders panel, Structural basal ganglia disorders panel, and Likely inborn error of metabolism panel. This extensive panel representation underscores NDUFS4's clinical importance in differential diagnosis of children presenting with complex neurological phenotypes and suspected metabolic dysfunction.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
How is NDUFS4-related Leigh syndrome inherited?
NDUFS4-related Leigh syndrome follows an autosomal recessive inheritance pattern, meaning an affected individual has inherited two pathogenic variants, one from each parent. Parents who each carry one pathogenic variant typically do not show symptoms but have a 25% chance with each pregnancy of having an affected child.
What is mitochondrial complex I and why is it important?
Mitochondrial complex I is the first and largest enzyme in the respiratory chain, responsible for initiating the process that generates cellular energy in the form of ATP. It transfers electrons from NADH to ubiquinone whilst pumping protons across the mitochondrial membrane, creating the energy gradient needed for ATP production. Deficiency in complex I activity impairs energy production throughout the body, particularly affecting high-energy tissues like the brain.
Can NDUFS4 variants cause symptoms in adulthood?
NDUFS4-related Leigh syndrome typically manifests in infancy or early childhood, with most affected individuals presenting before age two. Whilst the severity and progression can vary, adult-onset presentations are uncommon with this particular gene, in contrast to some other mitochondrial disorders that may present later in life.