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NDUFS7
NADH:ubiquinone oxidoreductase core subunit S7
NDUFS7 is located on the short (p) arm of chromosome 19, at band 19p13.3. Arm ratio per GRCh38 - banding schematic.
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Clinical tests that include this
Overview
NDUFS7 encodes NADH:ubiquinone oxidoreductase core subunit S7, a component of mitochondrial complex I (NADH dehydrogenase). Complex I is the first and largest enzyme assembly in the mitochondrial respiratory chain, comprising over 40 protein subunits that work together to generate cellular energy. The NDUFS7 protein serves as one of the core structural subunits essential for complex I assembly and catalytic activity.
Pathogenic variants in NDUFS7 follow an autosomal recessive inheritance pattern, meaning individuals must inherit altered copies from both parents to develop clinical features. Such variants disrupt complex I function, impairing the cell's ability to produce adenosine triphosphate (ATP), the primary energy currency. Tissues with high energy demands, particularly the brain and muscles, are typically most affected. The gene is included on multiple NHS clinical panels for mitochondrial disorders, reflecting its established role in inherited metabolic disease.
What the gene does
The NDUFS7 protein is a core subunit of complex I, which catalyses the first step of oxidative phosphorylation in mitochondria. This enzyme complex transfers electrons from NADH (the reduced form of nicotinamide adenine dinucleotide) to ubiquinone (coenzyme Q10), a reaction that releases energy used to pump protons across the inner mitochondrial membrane. The resulting proton gradient drives ATP synthesis, providing energy for virtually all cellular processes.
NDUFS7 contributes to the structural framework that organises the enzyme's catalytic machinery. Complex I consists of 45 subunits arranged in an L-shaped structure with a membrane arm and a matrix arm. NDUFS7 resides within the peripheral matrix arm, where it helps coordinate electron transfer between iron-sulphur clusters embedded in the protein scaffold. Proper assembly and stability of complex I depend on the presence of functional NDUFS7, making this subunit critical for efficient mitochondrial respiration. When NDUFS7 function is compromised, cells experience reduced ATP production and may accumulate reactive oxygen species, contributing to cellular dysfunction in affected tissues.
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Chromosome location
NDUFS7 is located on the short arm of chromosome 19 at position p13.3 (19p13.3). This chromosomal region contains numerous genes and is situated near the telomere of chromosome 19. The gene spans a relatively compact genomic region and encodes a mature protein of 213 amino acids following post-translational processing.
Protein structure
The NDUFS7 protein comprises 213 amino acids and forms part of the modular architecture of complex I. Structural studies indicate the protein contains a disordered region spanning amino acids 31 to 53, a segment that lacks fixed three-dimensional structure under physiological conditions. Such disordered regions can serve regulatory functions or provide flexibility for protein-protein interactions within the larger complex I assembly. The remainder of the protein adopts a folded structure that integrates into the matrix arm of complex I, where it participates in stabilising the electron transfer pathway.
Key variants
Pathogenic variants in NDUFS7 typically result in reduced or absent protein expression, compromising complex I assembly and enzymatic activity. Most disease-causing changes are loss-of-function variants, including nonsense mutations that introduce premature stop codons and frameshift variants that alter the protein sequence. Missense variants affecting critical structural residues have also been reported. The severity of clinical features often correlates with residual complex I activity, though genotype-phenotype relationships remain incompletely defined for this gene.
Sample of pathogenic variants
7 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.339_348del | p.Arg115fs | Pathogenic/Likely pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 3 |
c.343_352dup | p.Asp118fs | Pathogenic/Likely pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 3 |
g.(?_1390850)_(1391184_?)del | - | Pathogenic | ★☆☆☆ | not provided |
c.267C>A | p.Cys89Ter | Pathogenic | ★☆☆☆ | not provided |
c.2T>C | p.Met1Thr | Pathogenic | ★☆☆☆ | not provided |
c.94C>T | p.Gln32Ter | Pathogenic | ★☆☆☆ | not provided |
c.434G>A | p.Arg145His | Pathogenic | - | Mitochondrial complex I deficiency, nuclear type 3 |
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 NDUFS7 cause mitochondrial complex I deficiency, a severe metabolic disorder typically presenting in infancy or early childhood. Affected individuals often exhibit progressive neurological deterioration, including developmental regression, movement disorders, and intellectual disability. Additional features may include lactic acidosis, failure to thrive, and structural brain abnormalities such as white matter changes or basal ganglia lesions visible on brain imaging. The clinical presentation reflects the widespread energy deficit resulting from impaired mitochondrial function, with tissues that have high metabolic demands being particularly vulnerable.
No disease links recorded for this gene in our reference set.
Inheritance pattern
Conditions caused by pathogenic NDUFS7 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
NDUFS7 appears on multiple NHS Genomic Medicine Service PanelApp panels with green (high evidence) classification, reflecting its established role in inherited disease. The gene is included on the Mitochondrial disorder with complex I deficiency panel (R353) and the broader Mitochondrial disorders panel, both of which guide diagnostic testing in the NHS. Additional panel memberships include Likely inborn error of metabolism (R98), Intellectual disability (R29), Inherited white matter disorders, and Childhood onset dystonia, chorea or related movement disorder (R57). These panel inclusions support the use of NDUFS7 testing when clinical features suggest mitochondrial dysfunction, particularly in children presenting with unexplained neurological deterioration or metabolic abnormalities.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
What inheritance pattern does NDUFS7 follow?
NDUFS7-related conditions follow an autosomal recessive inheritance pattern. This means an individual must inherit pathogenic variants from both parents to develop clinical features. Parents who each carry one altered copy typically do not show symptoms.
Why does NDUFS7 dysfunction particularly affect the brain?
The brain has exceptionally high energy requirements, consuming a disproportionate amount of the body's ATP despite representing only a small fraction of body mass. When complex I function is impaired due to NDUFS7 variants, neurons and other brain cells cannot meet their energy demands, leading to the neurological features characteristic of mitochondrial disorders.
How is complex I deficiency diagnosed?
Diagnosis typically involves a combination of clinical evaluation, biochemical testing showing elevated lactate or reduced complex I enzyme activity in muscle or skin cells, brain imaging, and genetic testing. Definitive diagnosis requires identification of biallelic pathogenic variants in a gene such as NDUFS7 through genomic sequencing.