Mitochondrial Complex V Deficiency: Causes, Symptoms, and Treatment
Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 2, 2026.
What kind of doctor treats Mitochondrial Complex V Deficiency?
A primary care doctor usually starts the process, doing exams, ordering first tests, and watching overall health. Because this is a rare genetic condition, care often involves a specialist, most often a medical geneticist or a neurologist. They can handle day-to-day care and refer the patient to a specialist when the diagnosis is unclear.
What it is
Mitochondrial complex V deficiency is a rare condition that affects mitochondria, the tiny power plants inside cells. When complex V does not work well, cells do not get enough energy, hitting hardest in organs like the brain, heart, muscles, and liver. It can appear in babies and children, or later in life in milder form.
Symptoms
Symptoms depend on which organs are affected and how low the energy supply is. Many babies have weak muscle tone, trouble feeding or gaining weight, and a buildup of lactic acid in the blood, which can cause fast breathing and sleepiness. Other possible signs include delays in sitting, walking, or talking, heart problems, and hearing or vision loss.
Causes and who gets it
This condition is caused by mutations in genes that help build or run complex V. Some of these genes sit in the cell's main DNA; others sit inside the mitochondria themselves. Because of this, it can be passed down in different ways, sometimes from both parents who carry the gene change without being sick, and sometimes from the mother.
How doctors diagnose it
Diagnosis usually starts with a primary care doctor, who does an exam and orders basic tests. Blood and urine tests can check for lactic acid buildup, and scans such as an MRI can show organ changes. Genetic testing is often the key step, looking at a person's DNA for disease-causing changes.
Treatment
There is no cure; treatment focuses on easing symptoms and keeping the person as healthy as possible. Some people take supplements such as coenzyme Q10. Treatment may also include physical therapy, speech therapy, medicines for seizures, and regular heart checks. Infections can hit harder for people with mitochondrial disease, so vaccines and quick care for illness matter.
When to see a doctor
See a doctor if a baby or child has floppy muscles, poor feeding, slow growth, or delays in reaching milestones. Fast breathing, unusual sleepiness, or repeated vomiting also deserve a prompt visit. Adults with unexplained muscle weakness, extreme tiredness, or nerve problems should mention these to their doctor too.
Common questions
Is mitochondrial complex V deficiency the same for everyone?
No. Some people have serious problems starting in infancy. Others have milder symptoms that appear later. Doctors cannot always predict how the condition will progress for a given person.
Can this condition be cured?
There is no cure right now. Treatment aims to manage symptoms, support development, and prevent complications. Research on mitochondrial diseases is ongoing.
Should other family members be tested?
It can be worth discussing with a doctor or genetic counselor. A genetic counselor is a professional who explains inherited conditions and testing options. Because the condition can be passed down in different ways, testing advice depends on the family's specific gene change.
Can a person with this condition live a normal life?
Outcomes vary widely. Some people have mild symptoms and live full lives. Others need significant daily support. A care team can give a clearer picture for each individual situation.
Sources
- NIH Genetic and Rare Diseases Information Center - Diseases
- MedlinePlus Genetics - MedlinePlus: Genetic Conditions
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
