Human mitochondrial DNA, or mtDNA, is a small circular genome inside mitochondria. It has 37 genes: 13 help make proteins used for energy production, 22 make transfer RNAs, and 2 make ribosomal RNAs. mtDNA is usually inherited from the mother and can be linked to certain rare mitochondrial diseases 1.
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See if you qualify →What is mitochondrial DNA?
Mitochondrial DNA is the small set of genetic instructions found inside mitochondria, the energy-making parts of your cells. It is separate from nuclear DNA, which is the much larger genome stored in the cell nucleus 1.
If you want a deeper structure-first view, our guide to mitochondrial DNA structure explains why mtDNA is circular, compact, and different from the chromosomes in the nucleus.
How mitochondria help cells make usable energy
Mitochondria turn energy from food into adenosine triphosphate, or ATP, which cells use as a direct fuel source. The mtDNA genes help build parts of the enzyme systems used in oxidative phosphorylation, the oxygen-using process that makes much of the cell’s ATP 1.
Oxidative phosphorylation includes the electron transport chain. As electrons move through that chain, mitochondria help create the conditions needed to make ATP; reactive oxygen species can also form during this process, which is one reason mitochondrial biology is often discussed in aging research 3.
How mtDNA differs from DNA in the cell nucleus
Nuclear DNA contains most of your genes and is packaged in chromosomes inside the nucleus. mtDNA is much smaller, sits in the cytoplasm inside mitochondria, and represents only a small fraction of total DNA in human cells 1.
The two genomes work together. Many proteins needed by mitochondria are encoded by nuclear DNA, while mtDNA encodes a small but important set of energy-related instructions 1. For a side-by-side comparison, see our guide to mitochondrial DNA vs nuclear DNA.
What are the quick facts about mitochondrial DNA genes?
Human mtDNA has 37 genes, and its genome is about 16,500 base pairs long. These genes are essential for normal mitochondrial function, especially the cell’s ability to make ATP through oxidative phosphorylation 1.
- 37 total genes are found in human mitochondrial DNA 1.
- 13 genes provide instructions for proteins used in oxidative phosphorylation 1.
- 22 genes provide instructions for transfer RNAs, or tRNAs 1.
- 2 genes provide instructions for ribosomal RNAs, or rRNAs 1.
- mtDNA is usually inherited through the maternal line, which is why it is often used in ancestry and lineage studies 5.
How many genes are in human mitochondrial DNA?
Human mitochondrial DNA contains 37 genes. The main groups are 13 protein-coding genes, 22 transfer RNA genes, and 2 ribosomal RNA genes 1.
The 13 protein-coding genes
The 13 protein-coding mtDNA genes help make enzyme components involved in oxidative phosphorylation. These proteins are part of the machinery that helps cells create ATP, the main energy currency of the cell 1.
The 22 transfer RNA genes
Transfer RNAs, or tRNAs, help assemble amino acids into proteins. Human mtDNA contains 22 tRNA genes, which help mitochondria build the proteins encoded by mtDNA 1.
The 2 ribosomal RNA genes
Ribosomal RNAs, or rRNAs, are part of the protein-making machinery. Human mtDNA has 2 rRNA genes that help mitochondria assemble proteins inside the organelle 1.
| mtDNA gene group | Number of genes | What they do | Evidence type |
|---|---|---|---|
| Protein-coding genes | 13 | Provide instructions for enzyme components involved in oxidative phosphorylation and ATP production | Official genetics education source 1 |
| Transfer RNA genes | 22 | Help mitochondria translate genetic instructions into proteins | Official genetics education source 1 |
| Ribosomal RNA genes | 2 | Help form the mitochondrial protein-building machinery | Official genetics education source 1 |
For a gene-by-gene overview of what mtDNA encodes, see our article on what mitochondrial DNA codes for.
Why are mitochondrial DNA genes so special?
Mitochondrial DNA genes are special because they sit close to the cell’s ATP-making machinery and can exist in many copies per cell. They also have to coordinate with nuclear DNA to keep mitochondria working normally 1.
Many copies per cell
Each cell can contain hundreds to thousands of mitochondria, and mitochondria carry their own DNA 1. This means a cell may have many mtDNA copies, not just one.
When all mtDNA copies in a cell are the same, scientists call that homoplasmy. When normal and changed mtDNA copies are mixed, scientists call that heteroplasmy; the amount of changed mtDNA can affect whether symptoms appear and how severe they are 5.
Close connection to oxidative phosphorylation and ATP
The 13 protein-coding mtDNA genes support oxidative phosphorylation, which uses oxygen and simple sugars to make ATP 1. Because tissues like brain, muscle, heart, and eye tissue use a lot of energy, mitochondrial problems may show up strongly in those systems 7.
Higher vulnerability to damage and mutation
Mitochondrial DNA mutations can impair mitochondrial function and contribute to cellular energy failure 5. Researchers also study mitochondrial DNA mutations in heart, blood vessel, blood, and lung diseases, but a research link is not the same as a proven treatment target 9.
Coordination between mitochondrial DNA and nuclear DNA
Mitochondria are controlled by both nuclear genetic material and mitochondrial DNA 5. That is why a mitochondrial disorder can come from mtDNA changes, nuclear DNA changes, or problems that affect how the two systems work together.
What traits are inherited from mitochondrial DNA?
Mitochondrial DNA is usually inherited through the maternal line, but it does not determine most traits. Most inherited traits come from nuclear DNA, while mtDNA is most important for mitochondrial function and maternal-line ancestry 1.
Why mtDNA is usually passed through the maternal line
The embryo receives mitochondria mainly from the egg, which is why mtDNA usually follows maternal inheritance. This is the reason mtDNA can help trace maternal ancestry 5.
We explain this pattern in more detail in maternal mitochondrial inheritance, including why mtDNA inheritance is useful but easy to overinterpret.
Why mtDNA is useful for ancestry but does not determine most traits
mtDNA can help trace a maternal line because it is passed down in a distinct pattern. But traits like height, eye color, most disease risks, and most medication responses are not controlled by mtDNA alone; they usually involve nuclear DNA, environment, and many other factors 1.
Why nuclear DNA still controls most inherited traits
Most DNA is packaged in chromosomes inside the nucleus, and that nuclear genome contains most human genes 1. So mtDNA matters, but it is only one small part of the larger genetic picture.
What diseases are linked to mitochondrial DNA changes?
Mitochondrial DNA changes are linked to several rare disorders and some age-related conditions. Examples include MELAS, MERRF, Kearns-Sayre syndrome, Leber hereditary optic neuropathy, cytochrome c oxidase deficiency, cyclic vomiting syndrome, and age-related hearing loss 1.
Rare mitochondrial DNA disorders
Rare mitochondrial disorders can happen when mtDNA mutations, mtDNA deletions, or some nuclear DNA changes disrupt mitochondrial function. A clinical-trial listing for a natural history study notes that the m.3243A>G mitochondrial DNA mutation can be associated with migraines, seizures, stroke-like episodes, hearing loss, balance issues, gastrointestinal symptoms, and other symptoms 5.
MELAS stands for mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes. MERRF stands for myoclonic epilepsy with ragged-red fibers. These names sound technical because they describe symptom patterns seen in specialist care, not a diagnosis someone can make from a single symptom.
Examples of mtDNA-linked conditions
- MELAS: often linked to mtDNA mutations such as m.3243A>G, with neurologic and metabolic features studied in natural history research 5.
- MERRF: a rare mitochondrial disease pattern involving neurologic and muscle findings; mitochondrial disorders can involve disrupted cellular energy 2.
- Kearns-Sayre syndrome: listed by MedlinePlus Genetics among conditions associated with mitochondrial DNA changes 1.
- Leber hereditary optic neuropathy: listed by MedlinePlus Genetics among conditions associated with mitochondrial DNA changes 1.
- Cytochrome c oxidase deficiency: listed by MedlinePlus Genetics among conditions associated with mitochondrial DNA changes 1.
- Age-related hearing loss and cyclic vomiting syndrome: both are listed among conditions associated with mitochondrial DNA changes 1.
Why heteroplasmy can affect severity
In heteroplasmy, a person has a mix of changed and unchanged mtDNA. The proportion of changed mtDNA can differ across tissues, which helps explain why symptoms may vary by organ system and severity 5.
Can mitochondrial DNA genes affect aging or longevity?
Mitochondrial DNA changes are studied in aging, but they do not prove that any treatment extends human lifespan. Human and observational evidence can show links with age-related conditions, while animal or cell evidence can suggest mechanisms; neither should be treated as proof of longer human life 9.
Human evidence: age-related conditions
MedlinePlus Genetics notes that changes in mitochondrial DNA are among the best-studied genetic factors associated with age-related hearing loss 1. That is human genetics evidence for an association with a specific age-related condition, not proof that changing mtDNA would extend lifespan.
Observational and mechanism evidence: what it can show
NIH has identified mitochondrial DNA mutations as an important research area for understanding mechanisms in heart, blood vessel, blood, and lung diseases 9. This kind of research helps scientists ask better questions, but it does not show that a supplement, peptide, drug, or lifestyle plan changes mtDNA genes or extends human life.
At Chia, we discuss mitochondrial health carefully because longevity science can be overhyped. Our article on mitochondria and aging explains what changes with age, what is still being studied, and why biomarker changes are not the same as proven lifespan extension.
What this does and does not prove about human lifespan
A finding about mtDNA, ATP, oxidative stress, or a lab biomarker may be biologically interesting. But unless a human study measures meaningful outcomes, it should not be presented as proof that a treatment helps people live longer.
Chia offers some compounded longevity-related treatments, but we do not claim that any treatment changes mitochondrial DNA genes or extends human lifespan. Compounded drugs are not FDA-approved, and this article is education-only.
Can mitochondrial DNA genes affect medication response?
Mitochondrial DNA variation may affect drug response, but the evidence is still early. A systematic review found that studies have been heterogeneous, often underpowered, and often not replicated, so mtDNA testing is not ready for routine prescribing decisions in most cases 6.
What pharmacogenomics researchers are studying
Pharmacogenomics is the study of how genes may affect medication response. A 2021 systematic review found 24 studies from 2009 through 2020 that examined mtDNA variants and drug efficacy, toxicity, or resistance, including studies of antiretroviral, anticancer, and antimicrobial therapy response 6.
Why the evidence is not ready for most routine prescribing
The same review concluded that the field is limited by small studies, mixed methods, and lack of replication 6. In plain English: researchers are asking a real question, but most people should not expect mtDNA results to guide everyday medication choices yet.
Why clinician review still matters
Medication response depends on many things: kidney and liver function, other medications, pregnancy status, symptoms, allergies, medical history, and sometimes genetics. If you have known mitochondrial disease or unexplained neurologic, muscle, heart, vision, hearing, or metabolic symptoms, a clinician or genetics specialist can help decide what testing is appropriate.
How are mitochondrial DNA diseases studied or prevented?
Mitochondrial DNA diseases are studied through genetic testing, natural history studies, and specialist care. Prevention research includes mitochondrial replacement techniques, but these approaches are scientifically, ethically, and clinically complex 7.
Natural history studies and genetic testing in specialist care
A natural history study follows people over time without testing a treatment. One listed study of m.3243A>G carriers is designed to track neurologic and biochemical consequences using exams, MRI/MRS, questionnaires, motor testing, biomarkers, and genetic testing 5.
These studies help researchers understand how symptoms change over time. They can also help future trials choose better outcomes to measure.
Treatment research remains difficult
A 2013 review in Neurotherapeutics noted that treatment development for rare mitochondrial disorders has been difficult, and that care has often involved dietary supplements or off-label use of drugs approved for other conditions rather than FDA-approved mitochondrial-specific therapies 2. This should not be read as a recommendation to start supplements or off-label drugs without specialist care.
Mitochondrial replacement techniques
Mitochondrial replacement techniques, or MRT, are designed to reduce the risk of passing serious mitochondrial DNA diseases from mother to child. The approach involves nuclear DNA from the intended mother and mitochondrial DNA from a donor with nonpathogenic mtDNA 7.
The National Academies report explains that MRT raises scientific, ethical, social, and policy questions 7. Chia does not offer mitochondrial replacement techniques.
When should someone talk to a clinician or genetic specialist?
You should talk with a qualified clinician or genetics specialist if you have symptoms that suggest a mitochondrial disorder, a family history that follows the maternal line, or questions about genetic testing. This article cannot diagnose mitochondrial disease or interpret your personal genetic risk.
Family history patterns that may raise questions
A maternal-line pattern may raise a question about mtDNA inheritance. For example, symptoms appearing in a mother and several of her children may be more suggestive of mtDNA involvement than a pattern passed only from father to child, though only a genetics professional can interpret a real family history.
Symptoms that may prompt evaluation
Mitochondrial disorders can involve many body systems because high-energy tissues are often affected. Symptoms that may lead a clinician to consider specialist evaluation include unexplained seizures, stroke-like episodes, muscle weakness, exercise intolerance, hearing loss, vision loss, heart problems, developmental delay, or recurrent severe gastrointestinal symptoms 5.
What Chia can and cannot help with
At Chia, we focus on clinician-guided telehealth care in the areas listed in our current catalog. We do not offer mitochondrial DNA genetic testing, mitochondrial disease diagnosis, mitochondrial replacement techniques, or a treatment that changes mtDNA genes.
If your goal is general mitochondrial health education, our guide on how to improve mitochondrial health reviews lifestyle evidence, research limits, and when symptoms need medical care.
FAQ about mitochondrial DNA genes
Almost all human cells have mitochondria, and mitochondria contain mitochondrial DNA. Mature red blood cells are a major exception because they do not have mitochondria.
Mitochondrial DNA is usually inherited from the mother because the embryo gets most of its mitochondria from the egg. This is why mtDNA is useful for tracing the maternal line.
Human mitochondrial DNA has 37 genes: 13 protein-coding genes, 22 transfer RNA genes, and 2 ribosomal RNA genes.
No. Some mitochondrial diseases are caused by mtDNA changes, but others involve nuclear DNA or complex interactions between the two genomes. A genetics specialist can help decide which testing is appropriate.
No lifestyle habit or supplement has been proven to rewrite mitochondrial DNA genes in people. Healthy habits may support general metabolic health, but that is different from changing your mtDNA sequence.
No. mtDNA findings can help explain biology and disease risk, but biomarker or preclinical findings do not prove that a treatment extends human lifespan. Human outcomes matter.
Researchers are studying whether mtDNA variation can affect drug response, toxicity, or resistance. Current evidence is early and is not ready for routine prescribing decisions in most cases.
References
- 1.MedlinePlus Genetics. Mitochondrial DNA. National Library of Medicine, 2024.
- 2.Koenig MK. Presentation and Diagnosis of Mitochondrial Disorders in Children. Pediatric Neurology, 2008.
- 3.Taanman JW. The mitochondrial genome: structure, transcription, translation and replication. Biochimica et Biophysica Acta, 1999.
- 4.Taylor RW, Turnbull DM. Mitochondrial DNA mutations in human disease. Nature Reviews Genetics, 2005.
- 5.TrialX. Natural History Study - Mitochondrial Disease. Clinical trial listing, 2026.
- 6.Jones MM, Manwaring N, Wang JJ, Rochtchina E, Mitchell P, Sue CM. The Role of Mitochondrial DNA Variation in Drug Response. Pharmacogenomics and Personalized Medicine, 2021.
- 7.National Academies of Sciences, Engineering, and Medicine. Mitochondrial Replacement Techniques: Ethical, Social, and Policy Considerations. National Academies Press, 2016.
- 8.Parikh S, Goldstein A, Koenig MK, Scaglia F, Enns GM, Saneto R, Anselm I, Cohen BH, Falk MJ, Greene C, Gropman AL, Haas R, Hirano M, Morgan P, Sims K, Tarnopolsky M, Van Hove JLK, Wolfe L, DiMauro S. Diagnosis and management of mitochondrial disease: a consensus statement from the Mitochondrial Medicine Society. Genetics in Medicine, 2015.
- 9.National Institutes of Health. Mitochondrial DNA Mutations in Heart, Lung and Blood Diseases. NIH Guide, 1996.
About this article
Chia Health Editorial Team — Evidence-reviewed health education
This article is for educational purposes only and is not a substitute for individualized medical advice. Talk to a licensed clinician before starting, stopping, or changing any prescription.
AI tools may assist with research and drafting. Chia's editorial team reviews source use, clarity, treatment information, and safety framing before publication. A clinician is named only after explicit sign-off. Read our editorial standards.
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