MELAS, which stands for Mitochondrial Encephalomyopathy, Lactic Acidosis and Stroke-like episodes, is a mitochondrial disorder.¹ This condition affects various parts of the body, in particular the brain and nervous system, and muscles.^1,4 Symptoms include, but are not limited to, stroke-like episodes with seizures, headaches, vomiting and encephalopathy, with various neurological features.^1.2,4-6 Individuals with MELAS also have a build-up of lactic acid (lactic acidosis), which can result in muscle weakness, fatigue, difficulty breathing, abdominal pain and vomiting.^4,6 These symptoms usually present before 40 years of age, most typically in childhood,¹ and tends to be progressive.⁴

MELAS is a genetic condition, which is mainly caused by genetic changes in mitochondrial DNA that results in impaired function of the mitochondria (mitochondrial dysfunction).^1,4 As mitochondrial DNA is passed on from mother to child, females with MELAS are also likely to have children with MELAS.⁴

Synonyms: Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes; Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes.⁵

Universal rare disease classifications provide a common language for recording, reporting and monitoring diseases. Please visit the Rare Disease Classifications page for more information about these internationally recognised classifications.

ORPHA:550 MELAS

ICD-11: 8C73.Y Other specified mitochondrial myopathies

Common features of MELAS include stroke-like episodes, with seizures, headaches, vomiting and encephalopathy.¹ Individuals may have hearing impairment, cortical vision loss/blindness due to damage to the part of the brain involved in vision processing, learning disabilities and short stature.^{1, 4-6} Individuals often have increased levels of lactic acid (lactic acidosis) with muscle weakness, fatigue, difficult breathing, abdominal pain and vomiting.^4,6 There may also be a decline in cognitive and physical function.⁵

Please speak to your medical team to learn more about the symptoms of MELAS.

Rare diseases are often serious and progressive, exhibiting a high degree of symptom complexity, leading to significant disability. Majority of the estimated two million Australians living with a rare disease meet the Australian Government’s definition for disability (in accordance to the Australian Public Service Commission and Australian Bureau of Statistics), and many experience severe and permanent disability impacts. If you or someone you care for is experiencing disability-related impacts from a rare condition, please speak with a health or disability professional for advice. Information about relevant disability support can be found at the RARE Portal’s Disability Support Information page.

MELAS is caused by a disease-causing genetic change (variant) in mitochondrial DNA that result in impaired mitochondrial protein synthesis.¹ There have been at least 17 different mitochondrial genes associated with MELAS.  Genetic variants in either of those genes have been found to cause this condition. These genetic variants may occur randomly (de novo) prior to birth or are inherited from the mother as mitochondrial DNA is passed down from mothers to their children (maternal inheritance pattern).

More information on maternal/mitochondrial inheritance pattern can be found at Centre for Genetics Education: Mitochondrial inheritance.

If you would like to learn more about the inheritance and impact of this condition, please ask your doctor for a referral to a genetic counsellor. Genetic counsellors are qualified allied health professionals who can provide information and support regarding genetic conditions and testing. More information about genetic counselling can be found at:

• Information on Genetic Services
• The National and State Services pages underneath the ‘Genetic Counselling’ sections listed

A diagnosis of MELAS may be based on clinical features and findings, as well as genetic testing.⁶

Clinical tests may include brain imaging such as magnetic resonance imaging (MRI) to identify features of the stroke-like episodes, head computed tomography (CT) scans to look for calcium deposits, and magnetic resonance spectroscopy (MRS) to identify presence of increased lactate.^1,6

Biochemical analyses may involve measuring levels of lactate in the blood and in the cerebrospinal fluid (CSF; fluid that surrounds the brain and spinal cord), as well as levels of CSF protein.¹ Muscle biopsy may also be performed to look for mitochondrial abnormalities, such as the appearance of ragged red fibres.^1,6

Information about published clinical diagnostic criteria for MELAS can be found at GeneReviews®: MELAS – Diagnosis.

Genetic testing may be done to identify genetic variants that could be associated with MELAS. The genetic tests are usually performed on blood samples, but additional samples may be required from tissues such as from inner cheek (buccal mucosa), skin, hair, urine or skeletal muscle.^1,6

Please speak to your medical team to learn more about the available diagnostic pathways for MELAS.

There is currently no curative treatment for MELAS. Treatment is targeted at managing symptoms (symptomatic management) such as the stroke-like episodes, seizures and lactic acidosis and involves a multidisciplinary care team.^1,2 There may be contraindications to look out for when treating symptoms of MELAS.^1,2

It is also recommended that individuals with MELAS be regularly evaluated or monitored for issues with vision, hearing, and kidney, heart muscle disease (cardiomyopathy) or heart (cardiac) conduction defects, cognitive abilities and dementia, and diabetes mellitus.¹

Please speak to your medical team to learn more about the possible treatment or management options for your condition. Treatment will depend on an individual’s specific condition and symptoms. It is also important to stay connected to your medical team so that you can be made aware of any upcoming clinical trial opportunities.

Clinical care for rare diseases often involves a multidisciplinary team of medical, care and support professionals. Please note that the information provided here is as a guide and that RVA does not necessarily monitor or endorse specific clinics or health experts.

Healthcare professionals involved in the treatment of MELAS may include general practitioners (GP), paediatricians, metabolic physicians/consultants, geneticists, cardiologists, neurologists, and ophthalmologists.⁴ The need for different healthcare professionals may change over a person’s lifetime and extend beyond those listed here.

Please visit Mito Foundation: Find A Health Professional to request access to a directory of health professionals who have experience seeing individuals with mitochondrial disease.

Mito Foundation: Mito Clinics Directory contains information about Australian clinics, listed by state, that are relevant for individuals with mitochondrial disease.

Patient care standards for primary mitochondrial disease in Australia: an Australian adaptation of the Mitochondrial Medicine Society recommendations has been prepared by a working group of medical practitioners, nurses, and allied health professionals, and includes emphasis on clinical management relevant to Australian context for mitochondrial conditions, including MELAS.³

The following guidance is available from international experts outside Australia; however, there may be information that is not relevant or applicable to the Australian context, and may not be up to date:

Consensus-based statements for the management of mitochondrial stroke-like episodes – PMC (nih.gov), published in 2019, represents a group opinion of experts from multiple medical centres in the United Kingdom and Europe on stroke-like episodes associated with MELAS.²

Individuals living with rare diseases may have complex medical issues and disabilities, which are not always visible. It is often useful to refer to their medical history as well as personal information such as a medical card, doctor’s letter, or if available, a rare disease passport, for relevant information.

It may be important to consider the following when managing individuals living with MELAS at emergency departments/services:

• relevant specialists should be consulted
• individuals with MELAS may experience seizures and stroke-like episodes. There may be contraindications to consider when treating seizures in MELAS individuals.^1-3
• individuals with MELAS may also have a built up of lactic acid in the blood (lactic acidosis). It has been recommended that lactate levels are closely monitored during critical care³ and there may be contraindications to consider when treating lactic acidosis in individuals with MELAS.^1,2

Information regarding research and clinical work in the field of primary mitochondrial disease can be found at Research – Mito Foundation.

Monash University: The MitoHOPE (Healthy Outcomes Pilot and Evaluation) Program is a pilot introduction of mitochondrial donation into Australian clinical practice. Mitochondrial donation is an assisted reproductive technology which can help some women to avoid transmitting mitochondrial disease to their biological children.

There are specific considerations around participating in rare disease research, including clinical trials. It is important to be mindful of issues such as data privacy, research ethics, consent and differences in research regulations between Australia and other countries.

If you are interested in finding clinical trials for your condition, please visit the following websites; however, there may not be any clinical trials available:

• Australian Clinical Trials
• ClinicalTrials.gov

It is best to discuss your interest in any clinical trials with your medical team to determine suitability and eligibility.

Please note that RVA does not necessarily monitor or endorse each group/organisation’s operational governance and activities.

Australian Organisation:

Mito Foundation
Website: https://www.mito.org.au/contact/

The Mito Foundation is the only organisation dedicated to supporting and empowering people affected by mitochondrial disease (mito) in Australia. It provides resources and support services for people impacted by mito, and their families, while increasing awareness and understanding of this devastating disease. The foundation aims to transform outcomes for the mito community by driving meaningful change and funding essential research into the prevention, diagnosis, treatment and cures of mitochondrial disorders.

Please note that RVA does not monitor or endorse each group/organisation’s operational governance and activities. When engaging with a group, please consider the information on the RARE Portal’s Finding Helpful Peer and Community Supports page.

MELAS varies between individuals, and each person’s experience is unique.

Please visit Mito Foundation: Mito Stories (MELAS) to read the personal stories of people living with MELAS.

If you would like to share your personal story with RVA, please visit the Rare Voices Australia: Share Your Story page. RVA will consider your story for publishing on our website and inclusion on the RARE Portal.

Please visit Mito Foundation: MitoHub for people impacted by mitochondrial diseases. Support services provided by Mito Foundation include:

• Helpline – to talk to a support officer for general advice, assistance in seeking a referral or more information on Mito Foundation support services
• NDIS Navigation Service – to access education, resources and one-on-one guidance to NDIS supports and services through working with a NDIS navigator
• Peer Support – to connect with another person impacted by mito
• Mito Connect Events – to join an upcoming event to find out more about mito

For information on available government and social services that provide support for individuals with a rare disease, please visit the National and State Services pages.

People living with a rare disease, including families and carers, often face unique challenges such as diagnostic delays, misdiagnoses, limited treatment options, and limited access to rare disease specialists and support. These challenges may impact people’s emotional wellbeing and quality of life. Many people find it helpful to seek mental health and wellbeing support to cope with ongoing stress and uncertainty. Connecting with people who have shared experiences through a support group may also be helpful. Information about relevant mental health and wellbeing support can be found at:

• Mental Health and Wellbeing Support for Australians Living with a Rare Disease
• The National and State Services pages underneath the ‘Mental Health’ sections listed

Mito Foundation: Mental health support has information relevant to the mental wellbeing of individuals with a mitochondrial condition diagnosis.

Further information relating to mitochondrial conditions including MELAS can be found at:

• Mitochondrial Diseases (Group of Conditions)
• Mito Foundation: Types of Mito – MELAS
• Genetic and Rare Diseases (GARD) Information Center: MELAS
• National Organization for Rare Disorders (NORD): MELAS Syndrome

• Mito Foundation: For Health Professionals
• Mito Foundation: Maybe It’s Mito (for GPs)
• Mito Foundation: Health Professionals Continuing Professional Education
• GeneReviews®: MELAS
• Online Mendelian Inheritance in Man (OMIM): #540000 MITOCHONDRIAL MYOPATHY, ENCEPHALOPATHY, LACTIC ACIDOSIS, AND STROKE-LIKE EPISODES; MELAS
• Orphanet: MELAS
• Human Phenotype Ontology (HPO): MELAS

This page has been co-developed by Rare Voices Australia (RVA)’s RARE Portal team in consultation with Mito Foundation.¹

If you are aware of any additional information that may benefit stakeholders with an interest in this page, or if you notice any broken links or inaccurate information, please let us know via the Contribute page.