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NDUFAF2
NADH:ubiquinone oxidoreductase complex assembly factor 2
NDUFAF2 is located on the long (q) arm of chromosome 5, at band 5q12.1. Arm ratio per GRCh38 - banding schematic.
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Overview
NDUFAF2 (NADH:ubiquinone oxidoreductase complex assembly factor 2) encodes a protein that plays a critical role in assembling complex I, the largest enzyme complex within mitochondria. Complex I catalyses the first step of oxidative phosphorylation, the process by which cells convert nutrients into usable energy in the form of ATP. Without functional NDUFAF2, complex I cannot be properly assembled, leading to impaired cellular respiration.
Pathogenic variants in NDUFAF2 follow an autosomal recessive inheritance pattern, meaning that affected individuals inherit two altered copies of the gene, one from each parent. These variants cause mitochondrial disease characterised by progressive neurological decline, developmental delay, and features affecting the basal ganglia regions of the brain. NDUFAF2-related conditions are recognised within NHS genomic medicine pathways for mitochondrial disorders and metabolic investigations.
What the gene does
The NDUFAF2 protein functions as a molecular chaperone during the assembly of complex I, a large multi-subunit enzyme comprising numerous proteins. Complex I transfers electrons from NADH to ubiquinone whilst pumping protons across the inner mitochondrial membrane, establishing the electrochemical gradient that drives ATP synthesis. Assembly of this intricate structure requires multiple specialised factors that coordinate the incorporation of individual subunits and cofactors.
NDUFAF2 assists specifically during intermediate stages of complex I biogenesis, helping to stabilise nascent assembly intermediates and ensuring correct folding of core components. When NDUFAF2 is absent or non-functional, assembly stalls at specific checkpoints, resulting in accumulation of incomplete subcomplexes that are rapidly degraded. The consequent deficiency of mature complex I severely impairs mitochondrial respiration, reducing ATP production and increasing oxidative stress within affected cells. Tissues with high energy demands, particularly the brain and skeletal muscle, are especially vulnerable to this metabolic disruption.
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Chromosome location
NDUFAF2 is located on the long arm of chromosome 5 at position 5q12.1. This chromosomal region contains multiple genes involved in cellular metabolism and signalling. The precise genomic coordinates and exon structure contribute to the gene's regulation and the spectrum of variants observed in clinical practice.
Protein structure
The NDUFAF2 protein comprises 169 amino acids and contains a disordered region spanning amino acids 116 to 169. Disordered regions lack fixed three-dimensional structure and often mediate flexible protein-protein interactions, which may be important for NDUFAF2's role in recognising and stabilising diverse assembly intermediates during complex I biogenesis. The structured portion of the protein likely contains binding surfaces that interact with specific complex I subunits or other assembly factors, though detailed structural characterisation remains ongoing.
Key variants
Pathogenic variants in NDUFAF2 are typically loss-of-function alterations that abolish or severely reduce the protein's assembly factor activity. Reported variants include missense changes affecting critical residues, nonsense mutations leading to premature termination, and small deletions or insertions that disrupt the reading frame. Because NDUFAF2-related disease follows autosomal recessive inheritance, affected individuals carry biallelic pathogenic variants.
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.119dup | p.Asn40fs | Pathogenic/Likely pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 10 |
c.130_131del | p.Gln44fs | Pathogenic | ★★☆☆ | Leigh syndrome |
c.139C>T | p.Arg47Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 1 |
c.184del | p.Tyr62fs | Pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 10 |
c.1A>T | p.Met1Leu | Pathogenic/Likely pathogenic | ★★☆☆ | not provided |
c.221G>A | p.Trp74Ter | Pathogenic/Likely pathogenic | ★★☆☆ | NDUFAF2-related disorder |
g.(?_60241031)_(60369042_60394818)del | - | Pathogenic | ★☆☆☆ | Leigh syndrome |
g.(?_60368932)_(60394879_?)del | - | Pathogenic | ★☆☆☆ | not provided |
g.(?_60368932)_(60448782_?)del | - | Pathogenic | ★☆☆☆ | not provided |
c.192del | p.Asp66fs | Pathogenic | ★☆☆☆ | not provided |
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
Variants in NDUFAF2 cause a form of mitochondrial complex I deficiency characterised by progressive encephalopathy, developmental regression, and basal ganglia involvement. Clinical features often include hypotonia, seizures, movement disorders, and lactic acidosis. The age of onset and severity vary depending on the residual complex I activity, with earlier presentation generally associated with more profound enzyme deficiency. The condition is classified within the spectrum of nuclear-encoded mitochondrial disorders and is included in diagnostic pathways for undiagnosed metabolic conditions and structural brain disorders.
No disease links recorded for this gene in our reference set.
Inheritance pattern
Conditions caused by pathogenic NDUFAF2 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
NDUFAF2 holds green (high evidence) status on multiple NHS England PanelApp panels, reflecting its well-established role in human disease. It appears on the DDG2P panel for developmental disorders, the Mitochondrial disorders panel, and the more specific Mitochondrial disorder with complex I deficiency panel (R353). Additional green-rated inclusions cover Early onset or syndromic epilepsy (R59), Likely inborn error of metabolism (R98), Possible mitochondrial disorder - nuclear genes (R63), Structural basal ganglia disorders, and Undiagnosed metabolic disorders. These panel memberships guide clinicians in the NHS Genomic Medicine Service when selecting appropriate genomic tests for patients with suspected mitochondrial or metabolic disease.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
What is NDUFAF2 and what does it do?
NDUFAF2 encodes an assembly factor required for building complex I, the first enzyme in the mitochondrial respiratory chain. This protein helps ensure that complex I is correctly assembled so that cells can efficiently produce energy.
How are NDUFAF2 variants inherited?
NDUFAF2 variants follow an autosomal recessive inheritance pattern. This means an individual must inherit a pathogenic variant from both parents to develop the associated condition. Carriers, with one altered copy, typically do not show symptoms.
What symptoms are associated with NDUFAF2 variants?
Individuals with biallelic pathogenic NDUFAF2 variants typically present with progressive neurological decline, developmental delay, seizures, and movement disorders. Features often include involvement of the basal ganglia and metabolic abnormalities such as lactic acidosis.