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TMEM70 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

TMEM70 gene

The TMEM70 gene provides instructions for making a protein essential for mitochondrial energy production, and mutations in this gene are linked to mitochondrial complex V deficiency.

Normal Function

The TMEM70 gene provides instructions for making a protein called transmembrane protein 70. This protein is found in cell structures called mitochondria, which convert the energy from food into a form that cells can use. Transmembrane protein 70 is thought to play an important role in assembling and stabilizing a group of proteins called complex V. Complex V is the last of five complexes that carry out a multistep process called oxidative phosphorylation, through which cells derive much of their energy.

Complex V is involved in the final step of oxidative phosphorylation. Specifically, one segment of complex V allows positively charged particles, called protons, to flow across a specialized membrane inside mitochondria. Another segment of complex V uses the energy created by this proton flow to convert a molecule called adenosine diphosphate (ADP) to adenosine triphosphate (ATP), which is used by the cell as energy. Transmembrane protein 70 is also thought to be involved in the assembly of complex I, which is the first mitochondrial complex involved in oxidative phosphorylation.

Health Conditions Related to Genetic Changes

Mitochondrial complex V deficiency

At least 12 mutations in the TMEM70 gene have been identified in people who have mitochondrial complex V deficiency, a disorder with a wide variety of signs and symptoms. A few of these gene mutations are particular to people of Roma or Arab descent and account for the majority of mitochondrial complex V deficiency cases caused by TMEM70 gene mutations.

The signs and symptoms of mitochondrial complex V deficiency are most prominent in organs and tissues that require a large amount of energy, such as the brain and heart. Features include:

  • Abnormal brain function (encephalopathy) and other neurological problems.
  • Hypertrophic cardiomyopathy, characterized by thickening of the heart muscle that can lead to heart failure.

TMEM70 gene mutations alter transmembrane protein 70 and impair its ability to perform its function in complex V assembly. As a result, the amount of complex V in cells is reduced, impairing oxidative phosphorylation and energy production.

Other Names for This Gene

  • FLJ20533
  • MC5DN2
  • transmembrane protein 70, mitochondrial isoform a
  • transmembrane protein 70, mitochondrial isoform b

Frequently Asked Questions

Mitochondrial complex V deficiency can present with a wide range of symptoms, including severe developmental delay, muscle weakness (hypotonia), feeding difficulties, heart problems (cardiomyopathy), liver dysfunction, and lactic acidosis (buildup of lactic acid in the blood). The variability in symptoms is due to the widespread impact of energy deficiency on different tissues and organs, as well as the specific type and severity of the TMEM70 gene mutation.
Yes, mitochondrial complex V deficiency caused by TMEM70 gene mutations is inherited in an autosomal recessive pattern, meaning a child must inherit two mutated copies of the gene (one from each parent) to develop the condition. Certain populations, such as individuals of Roma or Arab descent, have a higher prevalence of specific TMEM70 gene mutations, making them more susceptible to this form of mitochondrial complex V deficiency. Genetic counseling is recommended for at-risk families.
Diagnosis typically involves a combination of clinical evaluation, blood tests to check for lactic acidosis and other metabolic abnormalities, and muscle biopsy to assess mitochondrial function. Genetic testing, usually performed on a blood sample, is crucial for confirming the diagnosis by identifying specific mutations in the TMEM70 gene. This can involve targeted gene sequencing or a broader mitochondrial gene panel.
There is currently no cure for mitochondrial complex V deficiency, and treatment focuses on supportive care to manage symptoms and improve quality of life. This may include nutritional support, medications to address specific symptoms (e.g., for heart or liver issues), and therapies to reduce lactic acid buildup. The long-term outlook is often poor, with many affected individuals experiencing severe neurological and systemic complications, and the condition can be life-limiting, especially in severe early-onset cases.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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