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PubMed This is a summary of 61 peer-reviewed journal articles Updated
Cardiology

Welcome to the Kearns-Sayre Syndrome Community

At a Glance

Kearns-Sayre Syndrome (KSS) is a rare, progressive mitochondrial disease diagnosed by three classic signs: onset before age 20, eye muscle weakness, and retinal changes. Management requires a multi-specialist team, particularly a cardiologist to monitor for potentially dangerous heart block.

Receiving a diagnosis of Kearns-Sayre Syndrome (KSS) can feel overwhelming. It is an extremely rare mitochondrial disease, a type of condition where the “power plants” of your cells—called mitochondria—do not produce enough energy for the body to function properly [1][2]. Because every person’s body uses energy differently, no two cases of KSS are exactly the same [3][4].

While the road ahead involves many medical appointments and monitoring, understanding the basics of the condition is the first step toward managing it effectively. This resource is designed to help you navigate this journey.

01

Symptoms and the Path to Diagnosis

Learn about Kearns-Sayre Syndrome (KSS) symptoms and the path to diagnosis. Understand early signs like drooping eyelids, heart risks, and misdiagnoses.

02

The Biology of Energy: Mitochondrial Deletions

Learn how mitochondrial DNA deletions cause Kearns-Sayre Syndrome (KSS). Understand heteroplasmy, mtDNA, and why KSS affects the heart, brain, and eyes.

03

Confirming the Diagnosis: Tests and Procedures

Learn how Kearns-Sayre syndrome (KSS) is diagnosed. Understand the role of mtDNA genetic testing, muscle biopsies, CSF analysis, and baseline health screenings.

04

Living with KSS: Managing Your Heart and Health

Learn how to manage Kearns-Sayre syndrome (KSS) symptoms. Understand heart health risks, pacemaker recommendations, endocrine care, and safe treatments.

05

Building Your Care Team: Specialists and Preparation

Learn how to build a care team for Kearns-Sayre Syndrome (KSS). Discover which specialists you need, what questions to ask, and how to prepare for your visits.

06

Looking Ahead: Monitoring and Your Future with KSS

Learn about long-term monitoring and prognosis for Kearns-Sayre syndrome (KSS). Understand surveillance schedules, managing fatigue, and questions to ask.

Understanding the “Classic Triad”

Doctors typically diagnose KSS based on three core features, often called the “classic triad.” To meet the formal definition of KSS, a person generally must show all three of these signs [5][6]:

  1. Onset Before Age 20: The first symptoms almost always appear during childhood or adolescence [5][7].
  2. Chronic Progressive External Ophthalmoplegia (CPEO): This is a medical term for a slow, progressive weakening of the muscles that move the eyes and keep the eyelids open (ptosis) [5][8].
  3. Pigmentary Retinopathy: This refers to a “salt-and-pepper” appearance of the retina (the light-sensing back of the eye) caused by changes in its pigment [5][9].

Beyond this triad, a diagnosis is often confirmed if a person also has at least one of the following: heart block (an interruption in the heart’s electrical signals), cerebellar ataxia (problems with balance and coordination), or high levels of protein in the fluid surrounding the brain and spine [7][10].

The Role of Mitochondria and Inheritance

To understand KSS, it helps to think of the body as a city. The mitochondria are the power plants that provide electricity to every building. In KSS, a piece of the “instruction manual” (the mitochondrial DNA) is missing, which causes the power plants to fail [1][8].

Because the heart, brain, and eyes are “high-energy” organs, they are often the first to be affected when the power supply drops [2][11]. KSS is almost always caused by a single, large-scale deletion (a missing piece) of mitochondrial DNA [1][12].

Will I pass this to my children? Unlike many genetic conditions, these large-scale deletions usually happen by chance (sporadically) during early development [1]. It is extremely rare for a parent to pass KSS down. However, because mothers pass mitochondrial DNA to their children, female patients should consult with a genetic counselor to discuss the precise, albeit very low, recurrence risks for their future children.

What to Expect

KSS is a multisystem disorder, meaning it can affect different parts of the body at different times.

  • Rarity: KSS is very rare. While exact global numbers are hard to find, some studies estimate it affects roughly 1.6 out of every 100,000 people [13][14].
  • Progressive Nature: Symptoms tend to develop and change over time. This makes regular check-ups—especially with a cardiologist to monitor heart rhythm—essential for safety [15][16].
  • Variability: The severity depends on how many “bad” mitochondria are present in different tissues, a concept called heteroplasmy [17][18]. This is why one person may have mild symptoms while another faces more significant challenges [3].

Navigating the Emotional Journey

Finding out you or your child has a rare, progressive disease often triggers a wave of emotions, from shock and grief to frustration [19]. It is normal to feel “diagnostic exhaustion” if you spent a long time searching for answers [19].

While KSS is a serious condition, many patients lead fulfilling lives with the help of a dedicated care team. Focusing on what you can control—such as consistent monitoring and connecting with support communities—can help you move from a place of fear to one of empowered management [20][19].

Common questions in this guide

What are the classic symptoms of Kearns-Sayre Syndrome?
The classic triad of KSS includes symptom onset before age 20, progressive weakness of the eye muscles (CPEO or ptosis), and pigmentary retinopathy, which changes the appearance of the retina. Doctors use these three core features to help confirm a diagnosis.
Is Kearns-Sayre Syndrome an inherited condition?
KSS is rarely passed down from a parent to a child. It is almost always caused by a sporadic, large-scale deletion of mitochondrial DNA that happens by chance during early development.
Why do I need to see a cardiologist for KSS?
KSS is a progressive disease that frequently affects the heart's electrical system, which can cause a serious condition called heart block. Regular cardiac monitoring is essential to catch and manage any heart rhythm issues safely.
What does heteroplasmy mean in mitochondrial disease?
Heteroplasmy refers to the mix of healthy and mutated mitochondria in your body's cells. The severity of your symptoms largely depends on how many affected mitochondria are present in different tissues, which explains why no two cases of KSS are exactly alike.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Can you confirm that my (or my child's) diagnosis meets the three classic criteria for KSS?
  2. 2.How does the specific mitochondrial DNA deletion identified in the testing affect the long-term outlook?
  3. 3.What is the immediate plan for cardiac monitoring to check for heart block?
  4. 4.Which specialists (like cardiologists, ophthalmologists, or neurologists) need to be on our core care team?
  5. 5.How often should we be screening for other common KSS features, like hearing loss or diabetes?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (20)
  1. 1

    Ophthalmoplegia in Mitochondrial Disease.

    Lee SJ, Na JH, Han J, Lee YM

    Yonsei medical journal 2018; (59(10)):1190-1196 doi:10.3349/ymj.2018.59.10.1190.

    PMID: 30450853
  2. 2

    Molecular Aspects of Mitochondrial Dysfunction in Diabetes, Pearson and Kearns-Sayre Syndromes, and Neurodegenerative Disorders.

    Shafiee A, Akhlaghi AA, Ellstrom A, et al.

    International journal of general medicine 2025; (18()):5355-5366 doi:10.2147/IJGM.S539967.

    PMID: 40959587
  3. 3

    Polyendocrinopathy and multisystem involvement are common phenotypic features of Kearns-Sayre syndrome.

    Finsterer J

    European journal of translational myology 2025; (35(2)) doi:10.4081/ejtm.2025.13634.

    PMID: 40226956
  4. 4

    Clinical and Brain Magnetic Resonance Imaging Features in a Cohort of Chinese Patients with Kearns-Sayre Syndrome.

    Yu M, Zhang Z, Wang QQ, et al.

    Chinese medical journal 2016; (129(12)):1419-24 doi:10.4103/0366-6999.183417.

    PMID: 27270536
  5. 5

    A rare case of Kearns-Sayre syndrome in a 17-year-old Venezuelan male with bilateral ptosis as the initial presentation.

    Leal M, Dhoble C, Lee J, et al.

    Oxford medical case reports 2016; (2016(3)):34-6 doi:10.1093/omcr/omw007.

    PMID: 26949540
  6. 6

    Teaching NeuroImages: Kearns-Sayre syndrome.

    Nguyen MTB, Micieli J, Margolin E

    Neurology 2019; (92(5)):e519-e520 doi:10.1212/WNL.0000000000006861.

    PMID: 30635486
  7. 7

    Exophthalmos in Kearns-Sayre syndrome.

    Tauber J, Polla DJ, Park S

    Journal of AAPOS : the official publication of the American Association for Pediatric Ophthalmology and Strabismus 2019; (23(5)):295-297 doi:10.1016/j.jaapos.2019.05.005.

    PMID: 31158487
  8. 8

    Should Patients with Kearns-Sayre Syndrome and Corneal Endothelial Failure Be Genotyped for a TCF4 Trinucleotide Repeat, Commonly Associated with Fuchs Endothelial Corneal Dystrophy?

    Dudakova L, Skalicka P, Davidson AE, et al.

    Genes 2021; (12(12)) doi:10.3390/genes12121918.

    PMID: 34946867
  9. 9

    Heart Block, Ptosis, and Diagnostic Funduscopic Examination: Problems of the Heart Seen Through the Eyes.

    Ramcharan CR

    The Canadian journal of cardiology 2018; (34(5)):690.e1-690.e3 doi:10.1016/j.cjca.2018.02.007.

    PMID: 29731029
  10. 10

    Kearns-Sayre syndrome presenting with fanconi syndrome: a case report.

    Lu Y, Jian S, Qian M, et al.

    Translational pediatrics 2025; (14(5)):1059-1064 doi:10.21037/tp-2025-138.

    PMID: 40519735
  11. 11

    CRISPR prime editing of mitochondrial heteroplasmy in rare Kearns-Sayre syndrome: ocular and cardiac synergies.

    Shahab SH, Habib F

    Annals of medicine and surgery (2012) 2026; (88(1)):1019-1020 doi:10.1097/MS9.0000000000004366.

    PMID: 41496996
  12. 12

    Mitochondrial disorders: Understanding mitochondrial DNA point mutations and deletion syndromes.

    Heuer B, Seibert DC

    Journal of the American Association of Nurse Practitioners 2022; (34(8)):954-956 doi:10.1097/JXX.0000000000000755.

    PMID: 36330549
  13. 13

    Mitochondrial DNA deletion and duplication in Kearns-Sayre Syndrome (KSS) with initial presentation as Pearson Marrow-Pancreas Syndrome (PMPS): Two case reports in Barranquilla, Colombia.

    Sabella-Jiménez V, Otero-Herrera C, Silvera-Redondo C, Garavito-Galofre P

    Molecular genetics & genomic medicine 2020; (8(11)):e1509 doi:10.1002/mgg3.1509.

    PMID: 33030289
  14. 14

    Unusual Phenotype and Disease Trajectory in Kearns-Sayre Syndrome.

    Finsterer J, Winklehner M, Stöllberger C, Hummel T

    Case reports in neurological medicine 2020; (2020()):7368527 doi:10.1155/2020/7368527.

    PMID: 32181031
  15. 15

    Prophylactic pacemaker placement at first signs of conduction disease in Kearns-Sayre syndrome.

    Trivedi M, Goldstein A, Arora G

    Cardiology in the young 2018; (28(12)):1487-1488 doi:10.1017/S1047951118001609.

    PMID: 30326976
  16. 16

    Progressive involvement of cardiac conduction system in paediatric patients with Kearns-Sayre syndrome: how to predict occurrence of complete heart block and sudden cardiac death?

    Di Mambro C, Tamborrino PP, Silvetti MS, et al.

    Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology 2021; (23(6)):948-957 doi:10.1093/europace/euaa335.

    PMID: 33336258
  17. 17

    Recognizing the evolution of clinical syndrome spectrum progression in individuals with single large-scale mitochondrial DNA deletion syndromes (SLSMDS).

    Ganetzky R, Stanley KD, MacMullen LE, et al.

    Genetics in medicine : official journal of the American College of Medical Genetics 2025; (27(5)):101386 doi:10.1016/j.gim.2025.101386.

    PMID: 39985363
  18. 18

    Response to Growth hormone deficiency in mitochondrial disorders.

    Quintos JB, Hodax JK, Gonzales-Ellis BA, et al.

    Journal of pediatric endocrinology & metabolism : JPEM 2017; (30(4)):483-484.

    PMID: 28315851
  19. 19

    Understanding the impact of pediatric single large-scale mtDNA deletion syndromes on caregivers: Burdens and challenges.

    Chappell M, Parikh S, Reynolds E

    JIMD reports 2023; (64(5)):375-386 doi:10.1002/jmd2.12385.

    PMID: 37701326
  20. 20

    Demographic characteristics, diagnostic challenges, treatment patterns, and caregiver burden of mitochondrial diseases: a retrospective cross-sectional study.

    Zhao X, Yu M, Zhang W, et al.

    Orphanet journal of rare diseases 2024; (19(1)):287 doi:10.1186/s13023-024-03289-5.

    PMID: 39095827

This page provides general educational information about Kearns-Sayre Syndrome. Always consult your neurologist or care team for specific advice regarding your diagnosis, monitoring, and disease management.

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