For You

child_care For Children & Teens

If you or someone in your family has this condition, this page is for you. No medical jargon - just the real stuff.

event Editorial update September 2026
Explanation

So, what's going on?

Mitochondria are tiny parts of your cells that help turn food into usable energy. Your body uses that energy for many jobs. Mitochondria support cellular ATP production through oxidative phosphorylation. 12

m.3243A>G is a change in some of the DNA inside mitochondria. It can make energy production work less well. The m.3243A>G MT-TL1 variant can impair mitochondrial translation and oxidative phosphorylation. 12

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Think of it like a phone battery

A battery can be a useful comparison, but your body is more complicated. There is no battery percentage that tells us how you will feel. Energy metaphors do not measure tissue bioenergetics or predict individual phenotype. 34

What might you notice?

People with this DNA change can feel very different from one another. The symptoms below are possibilities, not a list of things that will happen to you. m.3243A>G has variable penetrance and multisystem expression. 35

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Tiredness

You may get tired more easily. Tell your care team how tiredness affects school, friends or things you enjoy. Fatigue and its functional effects merit individual assessment. 67

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Hearing changes

Some people have hearing difficulties. Hearing aids, other devices and communication support may help. Audiological assessment guides amplification and other hearing support. 78

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Getting tired during exercise

If PE or activity is difficult, ask for help finding a version that fits you. You do not need to compete with someone else’s limits. Adapt physical activity to neuromuscular, cardiac and functional status. 79

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Headaches

Tell an adult about a new or very bad headache, confusion or changes in what you can see. These may need urgent medical help. New severe headache, encephalopathy or visual symptoms require prompt assessment. 710

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Diabetes

Some people develop diabetes, which affects blood sugar. Your team can explain any tests or treatment you need. Mitochondrial diabetes requires individual glycaemic assessment and treatment. 1112

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Tummy problems

Tell your team about feeling sick, stomach pain or trouble eating. They can help work out why it is happening. Gastrointestinal symptoms and reduced intake warrant assessment. 13

The important rules

There are a few things that are really important to know. These aren't scary - they're just things to keep in mind so you stay safe.

1

Tell your team about medicines

Let doctors and nurses know about your condition and show your personal medicine list. Your team can check which medicines fit your needs. Drug risk assessment depends on genotype, organ function and clinical context. 1415

2

Your food and drink plan

Follow the food and drink plan your team gives you. If you are sick and cannot eat or drink, tell an adult promptly. Use the individual reduced-intake and sick-day plan. 7

3

Rest is not weakness

Ask for a break or an activity change when you need one. Your team and school can help make a plan. School activity should reflect individual functional and clinical needs. 79

4

Tell someone if you feel wrong

Tell an adult straight away if you feel very confused, suddenly cannot see properly, have a very bad new headache or feel seriously unwell. Acute neurological change or severe systemic illness requires urgent assessment. 710

School stuff

school What your school should know
  • You might need extra breaks or a quiet place to rest during the day
  • PE should be flexible - you can participate, but you may need to sit out or do a lighter version
  • You might miss more school than average when you're unwell - that's not your fault
  • If you have hearing loss, you might need to sit near the front, use an FM system, or get notes in writing
  • Exams: you may qualify for extra time or rest breaks - ask about access arrangements
  • Ask whether snacks and drinks should be part of your school plan. Ask whether snacks and drinks should be part of your school plan.

Your parent or carer, school and care team can write down the support you need. The name and process for this plan depend on where you live. Your parent or carer, school and care team can write down the support you need. The name and process for this plan depend on where you live.

How to explain it to friends

You don't have to tell anyone if you don't want to. But if you do, here are some easy ways to explain it:

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“I have a condition that affects how my body makes energy. What I can manage changes, so I sometimes need a break or extra help.” “I have a condition that affects how my body makes energy. What I can manage changes, so I sometimes need a break or extra help.” 12

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“I have a genetic condition that can affect how my body makes energy. You cannot catch it. Some days I need extra help or rest.” “I have a genetic condition that can affect how my body makes energy. You cannot catch it. Some days I need extra help or rest.” 12

Some friends may need time or help to understand. A trusted adult can support you if a conversation is difficult. Some friends may need time or help to understand. A trusted adult can support you if a conversation is difficult.

If it's your brother or sister

Having a sibling with a chronic condition can bring up all sorts of feelings - and all of them are okay.

It's okay to feel left out

Sometimes your sibling gets more attention because of doctor visits or bad days. That doesn't mean you matter less. Talk to your parents about how you feel.

It's okay to feel worried

If you worry about your sibling, tell a trusted adult and ask questions. If you worry about your sibling, tell a trusted adult and ask questions.

It's not your job to fix it

Being kind and patient is enough. You don't need to be their nurse or give up your own life. You're allowed to have your own interests, friends, and feelings.

You might need to be tested too

If this DNA change is in your family, a genetics team can explain whether testing or check-ups would help you. You do not have to work it out on your own. Family-specific genetic counselling guides testing and surveillance. 1617

You're not alone

Other children, teenagers and adults live with mitochondrial conditions. Patient groups may help you meet people with similar experiences. Other children, teenagers and adults live with mitochondrial conditions. Patient groups may help you meet people with similar experiences.

References

17 sources

Sources for the information on this page.

  1. Goto Y, Nonaka I, Horai S. (1990). A mutation in the tRNA(Leu)(UUR) gene associated with the MELAS subgroup of mitochondrial encephalomyopathies. Nature. Research articleDOI↑ Back to text
  2. El-Hattab AW, Adesina AM, Jones J, Scaglia F. (2015). MELAS syndrome: Clinical manifestations, pathogenesis, and treatment options. Molecular genetics and metabolism. ReviewDOI↑ Back to text
  3. Pickett SJ, Grady JP, Ng YS, Gorman GS, Schaefer AM, Wilson IJ, Cordell HJ, Turnbull DM, Taylor RW, McFarland R. (2018). Phenotypic heterogeneity in m.3243A>G mitochondrial disease: The role of nuclear factors. Annals of clinical and translational neurology. Research articleDOIFull text↑ Back to text
  4. Grady JP, Pickett SJ, Ng YS, Alston CL, Blakely EL, Hardy SA, Feeney CL, Bright AA, Schaefer AM, Gorman GS, McNally RJ, Taylor RW, Turnbull DM, McFarland R. (2018). mtDNA heteroplasmy level and copy number indicate disease burden in m.3243A>G mitochondrial disease. EMBO molecular medicine. Research articleDOIFull text↑ Back to text
  5. Nesbitt V, Pitceathly RD, Turnbull DM, Taylor RW, Sweeney MG, Mudanohwo EE, Rahman S, Hanna MG, McFarland R. (2013). The UK MRC Mitochondrial Disease Patient Cohort Study: clinical phenotypes associated with the m.3243A>G mutation--implications for diagnosis and management. Journal of neurology, neurosurgery, and psychiatry. Research articleDOI↑ Back to text
  6. Klein IL, Verhaak CM, Smeitink JAM, de Laat P, Janssen MCH, Custers JAE. (2022). Identifying trajectories of fatigue in patients with primary mitochondrial disease due to the m.3243A > G variant. Journal of inherited metabolic disease. Research articleDOIFull text↑ Back to text
  7. Sue CM, Balasubramaniam S, Bratkovic D, Bonifant C, Christodoulou J, Coman D, Crawley K, Edema-Hildebrand F, Ellaway C, Ghaoui R, Kava M, Kearns LS, Lee J, Liang C, Mackey DA, Murray S, Needham M, Rius R, Russell J, Smith NJC, Thyagarajan D, Wools C. (2022). Patient care standards for primary mitochondrial disease in Australia: an Australian adaptation of the Mitochondrial Medicine Society recommendations. Internal medicine journal. Clinical guidanceDOIFull text↑ Back to text
  8. Varga L, Borecka S, Skopkova M, Rambani V, Sklenar M, Cipkova K, Kickova T, Ugorova D, Kabatova Z, Stanik J, Profant M, Gasperikova D. (2026). Screening for Maternally Inherited Diabetes and Deafness in Large Cohorts of Hearing Impaired and Diabetic Patients. Ear and hearing. Research articleDOIFull text↑ Back to text
  9. Wan Q, Ding Y, Liu W, Yang K. (2026). Effects of exercise training on skeletal muscle function in patients with mitochondrial myopathy: a systematic review. Frontiers in sports and active living. Systematic reviewDOIFull text↑ Back to text
  10. Mancuso M, Bellusci M, Carelli V, de Coo I, Diodato D, Distelmaier F, Hikmat O, Hirano M, Horvath R, Karaa A, Klopstock T, Koenig MK, Kornblum C, La Morgia C, Lopriore P, Martikainen MH, McFarland R, Musumeci O, Pitceathly RDS, Primiano G, Rahman S, Scaglia F, Schaefer A, Schiff M, Semmler L, Lamperti C, Servidei S. (2026). Diagnostic Criteria and Management of MELAS and Stroke-Like Episodes: Consensus-Based Statements. European journal of neurology. Clinical guidanceDOIFull text↑ Back to text
  11. Chanoine JP, Thompson DM, Lehman A. (2025). Diabetes Associated With Maternally Inherited Diabetes and Deafness (MIDD): From Pathogenic Variant to Phenotype. Diabetes. ReviewDOIFull text↑ Back to text
  12. Chaudhry A, Thompson DM, Chanoine JP. (2026). Diabetes management in maternally inherited diabetes and deafness (MIDD): A review and a proposed treatment algorithm. Diabetes, obesity & metabolism. ReviewDOIFull text↑ Back to text
  13. de Laat P, Zweers HE, Knuijt S, Smeitink JA, Wanten GJ, Janssen MC. (2015). Dysphagia, malnutrition and gastrointestinal problems in patients with mitochondrial disease caused by the m3243A>G mutation. The Netherlands journal of medicine. Research article↑ Back to text
  14. De Vries MC, Brown DA, Allen ME, Bindoff L, Gorman GS, Karaa A, Keshavan N, Lamperti C, McFarland R, Ng YS, O'Callaghan M, Pitceathly RDS, Rahman S, Russel FGM, Varhaug KN, Schirris TJJ, Mancuso M. (2020). Safety of drug use in patients with a primary mitochondrial disease: An international Delphi-based consensus. Journal of inherited metabolic disease. Clinical guidanceDOIFull text↑ Back to text
  15. Mancuso M, Papadopoulou MT, Ng YS, Ardissone A, Bellusci M, Bertini E, Di Vito L, Evangelista T, Fons C, Hikmat O, Horvath R, Klopstock T, Kornblum C, Lamperti C, Licchetta L, Molnar MJ, Varhaug KN, O'Callaghan M, Pressler RM, Schiff M, Servidei S, Szabo N, Gorman GS, Cross JH, Rahman S. (2024). Management of seizures in patients with primary mitochondrial diseases: consensus statement from the InterERNs Mitochondrial Working Group. European journal of neurology. Clinical guidanceDOIFull text↑ Back to text
  16. Smeets HJM, Sallevelt SCEH, Herbert M. (2023). Reproductive options in mitochondrial disease. Handbook of clinical neurology. ReviewDOI↑ Back to text
  17. Castelluccio N, Spath K, Li D, De Coo IFM, Butterworth L, Wells D, Mertes H, Poulton J, Heindryckx B. (2025). Genetic and reproductive strategies to prevent mitochondrial diseases. Human reproduction update. ReviewDOI↑ Back to text

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