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NDUFAF5
NADH:ubiquinone oxidoreductase complex assembly factor 5
NDUFAF5 is located on the short (p) arm of chromosome 20, at band 20p12.1. Arm ratio per GRCh38 - banding schematic.
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Overview
NDUFAF5 provides instructions for making NADH:ubiquinone oxidoreductase complex assembly factor 5, a protein that plays a critical role in mitochondrial energy production. Mitochondria generate adenosine triphosphate (ATP), the cell's primary energy currency, through a process called oxidative phosphorylation. This process relies on a series of enzyme complexes embedded in the inner mitochondrial membrane, collectively known as the respiratory chain.
Complex I, also called NADH dehydrogenase, is the largest of these enzyme complexes, comprising more than 40 individual protein subunits. NDUFAF5 does not form part of the mature complex itself but instead functions as an assembly factor, facilitating the correct assembly and incorporation of subunits during complex I biogenesis. Pathogenic variants in NDUFAF5 disrupt this assembly process, leading to mitochondrial dysfunction and a spectrum of clinical features that typically emerge in infancy or early childhood.
What the gene does
The NDUFAF5 protein operates within the mitochondrial matrix, where it supports the stepwise assembly of complex I. During complex I biogenesis, individual subunits must be brought together in a precise sequence, and assembly factors like NDUFAF5 coordinate these steps to ensure structural integrity. Research suggests that NDUFAF5 participates in intermediate assembly modules, particularly those involving the hydrophobic membrane arm of the complex.
When complex I assembly fails, cells cannot efficiently transfer electrons from NADH to ubiquinone, impairing the mitochondrial respiratory chain. This deficiency reduces ATP synthesis and can lead to the accumulation of reactive oxygen species, which may damage cellular components. Tissues with high energy demands, such as the brain, heart, and skeletal muscle, are especially vulnerable to mitochondrial dysfunction. The loss of NDUFAF5 function therefore manifests clinally in organs that rely heavily on oxidative metabolism, producing neurological and systemic features characteristic of mitochondrial disease.
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Chromosome location
NDUFAF5 is located on the short arm of chromosome 20 at position 12.1, designated 20p12.1. This chromosomal region contains several genes involved in diverse cellular processes. The NDUFAF5 gene spans multiple exons that together encode a 345-amino-acid protein.
Protein structure
Domain architecture has not been experimentally characterised in detail for this protein.
Key variants
Pathogenic variants in NDUFAF5 typically result in loss of protein function, disrupting complex I assembly. Most reported variants are rare, and affected individuals often carry compound heterozygous variants or homozygous changes inherited from carrier parents. The clinical severity can vary depending on the extent to which complex I assembly is compromised.
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.779delG | - | Pathogenic/Likely pathogenic | ★★☆☆ | Mitochondrial complex I deficiency |
c.204del | p.Phe68fs | Pathogenic/Likely pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 16 |
c.408dup | p.Ser137fs | Pathogenic/Likely pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 16 |
c.440del | p.Phe147fs | Pathogenic/Likely pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 16 |
c.445G>T | p.Glu149Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 16 |
c.489G>A | p.Trp163Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 16 |
c.529del | p.Ile177fs | Pathogenic/Likely pathogenic | ★★☆☆ | Mitochondrial complex I deficiency |
c.552dup | p.Ile185fs | Pathogenic/Likely pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 16 |
c.690del | p.Arg231fs | Pathogenic/Likely pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 16 |
c.826C>T | p.Arg276Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Mitochondrial complex I deficiency, nuclear type 16 |
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 NDUFAF5 cause mitochondrial complex I deficiency, an inherited metabolic disorder characterised by impaired energy production. Clinical presentations are heterogeneous but commonly include early-onset neurological features such as developmental delay, epilepsy, and movement disorders. Some individuals also develop muscle weakness, cardiomyopathy, or liver dysfunction. Because mitochondrial disease can affect multiple organ systems, the phenotype associated with NDUFAF5 variants overlaps with other genetic causes of complex I deficiency, and biochemical testing of respiratory chain enzyme activity is often required to establish the underlying defect.
No disease links recorded for this gene in our reference set.
UK clinical status
NDUFAF5 is included on several NHS Genomic Medicine Service gene panels, reflecting its role in diagnosing mitochondrial and metabolic disorders. These panels include Mitochondrial disorders, Mitochondrial disorder with complex I deficiency (panel R353), Likely inborn error of metabolism (panel R98), and Possible mitochondrial disorder - nuclear genes (panel R63). The gene also appears on panels for Childhood onset dystonia, chorea or related movement disorder (panel R57), Early onset or syndromic epilepsy (panel R59), Fetal anomalies (panel R21), and Undiagnosed metabolic disorders. Green classification on these panels indicates that there is strong evidence supporting NDUFAF5 as a disease-causing gene in these clinical contexts, and testing may be offered through the NHS for eligible individuals with relevant clinical features.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
What does NDUFAF5 stand for?
NDUFAF5 stands for NADH:ubiquinone oxidoreductase complex assembly factor 5. The name reflects its role in assembling complex I, which transfers electrons from NADH to ubiquinone during mitochondrial energy production.
How is NDUFAF5-related mitochondrial disease inherited?
NDUFAF5-related mitochondrial disease is typically inherited in an autosomal recessive pattern. This means an affected individual inherits one pathogenic variant from each parent, who are usually unaffected carriers.
Can NDUFAF5 variants be detected through carrier screening?
Yes, carrier screening can identify individuals who carry one pathogenic variant in NDUFAF5. Carriers do not usually have symptoms, but if both parents are carriers, each pregnancy has a 25% chance of being affected by mitochondrial complex I deficiency.