MERRF Syndrome

By | June 8, 2022

MERRF syndrome is a maternally inherited mitochondrial disease. The disease manifests itself primarily as encephalopathy with muscle weakness and epilepsy. A causal therapy is not yet available.

What is MERRF Syndrome?

Mitochondria are cell organelles that are referred to as the powerhouse of the cell. They are responsible for providing energy in the form of ATP. In mitochondriopathies, these power plants are damaged or malfunction. All mitochondriopathies have weakness in common as a key symptom. Medicine distinguishes between hereditary primary and acquired secondary mitochondrial diseases. For lms – limb mammary syndrome, please visit

MERRF ( Myoclonic Epilepsy with Ragged Red Fibers ) syndrome is a primary or inherited mitochondrial disease with atypical, oligo- and asymptomatic mutation carriers. The disease manifests itself clinically as mitochondrial encephalopathy. It is a progressive disease that usually begins in early adulthood. The disease often overlaps with other diseases from the group of mitochondriopathies.

Most often there is an overlap with the MELAS syndrome. The complex of MELAS and MERRF syndrome is called MERRF/MELAS overlap syndrome. The prevalence of mitochondriopathies for children is 1:5000 or 17 per 100000 inhabitants. The exact proportion of the MERRF syndrome has not yet been clarified.


MERRF syndrome is based on a mutation. Most commonly, patients suffer from a point mutation that causes tRNA misexpression. In the majority of cases, the point mutations occur on the tRNA-Lys gene at position 8344 and thus affect the mitochondrial DNA. The mutation is a maternally inherited mutation. The point mutation of A8344G causes disruptions in codon-anticodon recognition. Undisturbed codon-anticodon recognition is crucial for post-transcriptional modification.

Due to the mutation, the modification of the tRNA-Lys at the wobble base U34 is disrupted for patients with the MERRF syndrome. One consequence of this is a disturbed synthesis of mitochondrial proteins. Since mitochondrial proteins are responsible for oxidative phosphorylation, the patients suffer from disturbed phosphorylation processes. Cell destruction is the result. In addition, there is usually reduced activity of respiratory chain complexes.

Heteroplasmy is also characteristic. In addition to the mutated DNA, there is also a certain amount of normal DNA. The relationship between these components changes as the disease progresses.

Symptoms, Ailments & Signs

Neuromuscular complaints are the main symptom of the MERRF syndrome. These conditions include myoclonus and muscle weakness. The myoclonus manifests itself in the form of involuntary twitching of individual muscle groups or muscles. Central nervous failures of various kinds can also occur. Epileptic seizures, which develop progressively, are also characteristic.

The frequency and severity of seizures increases accordingly as the disease progresses. Deafness may be an accompanying symptom. Cerebellar ataxia and other movement impairments are also conceivable. Both fine motor skills and gross motor skills and balance are impaired. In addition to polyneuropathies, short stature, cardiac insufficiency and reduced respiratory drive can be present.

Endocrine disorders or lipomas can also be considered as accompanying symptoms. Those affected also often suffer from mental retardation or dementia brain changes. The patient’s musculature is affected by the characteristic changes in the form of “ragged red fibers”. Shaggy red fibers are therefore found in individual muscle groups.

As an encephalopathy, MERRF syndrome affects the brain as a whole. This applies above all to the degenerative mitochondrial cell deaths. If there is an overlap with the MELAS syndrome, other symptoms can be added.

Diagnosis & course of disease

The diagnosis of MERRF syndrome is a complex process. In addition to a family history, the neurological status of the patient is recorded. The laboratory findings show an increased lactate level with an increase in the stress test. The MRI image may show lesions or atrophies in the cerebellum, brainstem, or basal ganglia. With a muscle biopsy, diffusely limited, reddish muscle fibers can be detected.

Genetic diagnostics by means of molecular genetic examinations provide definitive certainty. PCR amplification and gel electrophoretic sequence analyzes are used for molecular genetic diagnostics. Molecular genetic studies enable a particularly early diagnosis. Prenatal diagnosis is conceivable.

In the case of a diagnosis after birth, the doctor assesses the overlap with other mitochondriopathies and gets an overview of the previously affected brain regions. For prenatal diagnosis, prognosis is often difficult. However, the MERRF syndrome is generally associated with severe disability or even death. The exact prognosis depends heavily on the individual course of the disease of the patient.


First and foremost, the MERRF syndrome leads to severe muscle weakness. As a result, those affected can no longer easily carry out certain everyday activities or various sports and are also dependent on the help of other people for some activities. The quality of life is significantly reduced by the MERRF syndrome.

The resilience also decreases. Most patients also suffer from epilepsy due to the syndrome. In the worst case, this can lead to the death of the patient. Furthermore, limitations in movement and balance disorders occur. Those affected also suffer from heart defects and short stature.

It is not uncommon for MERRF syndrome to also cause mental complaints, so that those affected usually also suffer from severe mental retardation. The syndrome can also lead to psychological problems or depressive moods for relatives and parents. A causal treatment of the MERRF syndrome is not possible.

The symptoms themselves are limited with the help of medication and therapy. In most cases, MERRF syndrome does not lead to a reduction in life expectancy. However, not all complaints can be cured.

When should you go to the doctor?

If the person concerned suffers from problems with the muscles, this is considered unusual. If the symptoms persist or increase in intensity, a doctor is needed. In the case of muscle fiber twitching, impaired muscle strength or pain, a doctor’s visit is required. If muscle weakness is noticed or if there is an incomprehensible reduction in muscle strength, there is a need for action. To determine the cause of the disturbances, a doctor should be consulted. A doctor should be consulted in the event of restricted mobility, gross motor movements or balance disorders.

If the person concerned suffers from hearing loss, changes in memory or a decrease in mental performance, a doctor should be consulted. A loss of memory is a warning signal from the organism for an existing disease that needs to be clarified. Short stature, heart rhythm problems and breathing disorders are further indications of an irregularity. Medical investigations must be initiated to determine the cause.

If breathing stops, sleep disorders or fears due to the existing health problems, a doctor is needed. If epileptic seizures occur, an emergency service must be alerted immediately. Until his arrival, first aid measures must be taken to ensure the survival of the person concerned. A loss of consciousness and disturbances in voluntary movements are signs of a seizure disorder that must be treated by a doctor as soon as possible.

Treatment & Therapy

So far, the MERRF syndrome is incurable. A causal therapy does not exist. Supportive and symptomatic treatments are available. The aim of these treatments is primarily to improve the quality of life. This goal is primarily intended to reduce the number of epileptic seizures in patients. The administration of antiepileptic drugs and muscle relaxants is obligatory. The muscular symptoms can be improved in particular by administering high-dose coenzyme Q10.

Various general treatments are recommended for mitochondria. In this context, for example, drugs such as carbamazepine, levetiracetam and oxcarbazepine are recommended. Drugs such as valproate can increase the symptoms of mitochondrial diseases and are therefore controversial. Patients with MERRF syndrome are also often recommended physical therapy and early intervention.

Physiotherapeutic measures ideally reduce movement restrictions. Early support aims to counteract cognitive impairments. Affected families can also seek psychotherapy to learn how to better deal with the disease. Various therapies for MERRF syndrome are currently the subject of medical research. Through gene therapy, medicine will probably be able to positively influence the causative mutation in the future.

Outlook & Forecast

With the MERRF syndrome, patients cannot expect a cure from the disease given the current medical and legal standards. The cause of the disease can be traced back to a mutation in a gene. Doctors treat the congenital disorder symptomatically. Since human genetics cannot be modified for legal reasons, physicians and medical professionals have so far had no other option to improve the situation.

Despite all efforts, the affected person experiences a severe impairment of his quality of life. In addition to physical abnormalities, depending on the intensity of the existing irregularities, cognitive losses can also occur. Despite early intervention programs, most ailments do not achieve complete healing or the mental level of an average person. The treatment plan drawn up consists of the administration of medication and support for the muscular system. The patient has to undergo long-term therapy with this disease. The course of the disease is significantly improved if self-help measures are used independently in everyday life.

Physiotherapeutic exercises should achieve an optimized range of motion. The results show a clear improvement when the training sessions are also carried out outside of the session taking place. Due to the large number of possible disorders, it can lead to a strong emotional burden. Therefore, the risk of developing a mental illness is increased in the MERRF syndrome.


So far, the MRRF syndrome can only be prevented as part of family planning. For example, a couple with an increased risk may decide not to have children of their own. After a prenatal diagnosis, the option of an abortion should be considered.


As a rule, various complications and symptoms can occur as a result of the MERRF syndrome, which can make life significantly more difficult for those affected and thus also reduce the patient’s quality of life. Since the disease is a congenital condition, follow-up care focuses on managing the symptoms well.

Most of those affected can no longer cope with their everyday life on their own and are therefore dependent on constant help. Due to the mental retardation, the development of the child is usually severely delayed. Due to the severe mental stress, the patient’s parents and relatives often suffer from psychological problems or depression. Professional psychological help can reduce the suffering and offer strategies to better understand and accept the situation. Since the MERRF syndrome cannot be completely cured, those affected are dependent on appropriate, purely symptomatic treatment.

You can do that yourself

In the case of MERRF syndrome, the most important self-help measure is to have all symptoms and complaints clarified immediately by a specialist. The individual symptoms can be very acute, which is why close medical monitoring is indicated.

At the same time, measures to improve the quality of life must be taken, such as physical activity and diets, but also the administration of drugs. Physiotherapeutic measures support the drug treatment. If possible, support should begin in childhood, as this can effectively counteract cognitive impairments. Parents and relatives often need therapeutic support. The responsible doctor can refer the parents to a suitable psychologist and, if necessary, also establish contact with other affected persons.

If a seizure or an epileptic fit occurs, the emergency doctor must be called immediately. Until medical help arrives, the affected person should be sedated and, if possible, placed in a lying position. In order to ensure smooth treatment, the emergency doctor must be informed immediately about the illness. After a hospital stay, rest and protection are necessary. A doctor needs to determine the cause of the symptoms to reduce the risk of future attacks.

MERRF Syndrome