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MERRF syndrome

ICD-10 Codes

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Description

MERRF (Myoclonic Epilepsy with Ragged Red Fibers) syndrome is a rare and complex disorder that affects multiple systems in the body, particularly the muscles and nervous system.

Characteristics of MERRF Syndrome:

  • Muscle involvement: MERRF syndrome is characterized by muscle weakness, myoclonus (brief, sudden muscle jerks), and ragged red fibers on muscle biopsy.
  • Neurological symptoms: The disorder also affects the nervous system, causing generalized epilepsy, ataxia (impaired coordination), and dementia.
  • Progressive nature: MERRF syndrome is a progressive multi-system syndrome that worsens over time.

Other common findings:

  • Hearing loss
  • Short stature
  • Optic atrophy
  • Cardiomyopathy with Wolff-Parkinson-White (WPW) syndrome

Age of onset: Symptoms usually first appear in childhood or adolescence after normal early development, but can also occur in adulthood.

Causes: MERRF syndrome is caused by mutations in the mitochondrial DNA (mtDNA), with the A8344G mutation being a common cause.

References:

  • [1] Description. Myoclonic epilepsy with ragged-red fibers (MERRF) is a disorder that affects many parts of the body, particularly the muscles and nervous system.
  • [2] MERRF syndrome affects different parts of the body, particularly the muscles and nervous system.
  • [3] A rare mitochondrial oxidative phosphorylation disorder characterized by myoclonic seizures, ataxia, generalized epilepsy, muscle weakness and rag

Additional Characteristics

  • A rare and complex disorder that affects multiple systems in the body, particularly the muscles and nervous system.
  • Myoclonic epilepsy with ragged-red fibers (MERRF) is a disorder that affects many parts of the body, particularly the muscles and nervous system.
  • A rare mitochondrial oxidative phosphorylation disorder characterized by myoclonic seizures, ataxia, generalized epilepsy, muscle weakness and ragged red fibers on muscle biopsy.

Signs and Symptoms

MERRF Syndrome Signs and Symptoms

MERRF (Myoclonic Epilepsy with Ragged Red Fibers) syndrome is a rare mitochondrial disorder that affects multiple systems in the body, particularly the muscles and nervous system. The primary features of this condition include:

  • Muscle twitches: Sudden, brief jerking spasms that can affect the limbs or entire body [7]
  • Myoclonus: Muscle twitches are often the first symptom to appear [3][13]
  • Recurrent seizures: Generalized epilepsy is a common feature of MERRF syndrome [2][3][8]
  • Ataxia: Uncoordinated movements and balance problems [4][5][6]
  • Muscle weakness: Abnormal muscle cells, known as ragged-red fibers, are characteristic of this condition [1][2][5]
  • Ragged red fibers (RRF): Abnormal muscle cells that appear stained and "ragged" under a microscope [1][2][4]
  • Dementia: Cognitive decline is a possible symptom in advanced cases [3][13]

Other clinical manifestations of MERRF syndrome may include:

  • Hearing loss
  • Peripheral neuropathy
  • Cognitive decay
  • Short stature
  • Exercise intolerance
  • Optic atrophy and ataxia

It's essential to note that the age of onset and progression of symptoms can vary greatly between individuals, even within the same family. Symptoms usually first appear in childhood or adolescence after a period of normal early development [11][13].

Additional Symptoms

  • Myoclonus
  • Hearing loss
  • Exercise intolerance
  • Peripheral neuropathy
  • Dementia
  • Recurrent seizures
  • Muscle twitches
  • Ragged red fibers (RRF)
  • Cognitive decay
  • Optic atrophy and ataxia
  • ataxia
  • muscle weakness
  • short stature

Diagnostic Tests

Diagnostic Tests for MERRF Syndrome

MERRF (Myoclonus Epilepsy with Ragged Red Fibers) syndrome can be diagnosed based on a combination of clinical findings and molecular genetic testing.

  • Clinical Diagnosis: A clinical diagnosis of MERRF can be made based on the presence of four features: myoclonus, generalized epilepsy, ataxia (impaired ability to coordinate movements), and abnormal muscle cells showing ragged red fibers (RRF) when a muscle biopsy is performed [1].
  • Molecular Genetic Testing: The diagnosis of MERRF syndrome relies on the demonstration of abnormal lactate accumulation in blood or cerebrospinal fluid, and on the muscle biopsy, which reveals the presence of cytochrome c oxidase negative muscle fibers and ragged red fibers [2].
  • Muscle Biopsy: A muscle biopsy is a crucial diagnostic test for MERRF syndrome. It helps to identify the presence of ragged red fibers (RRF), which are characteristic of mitochondrial disorders, including MERRF [3].
  • Imaging Studies: Imaging studies such as MRI brain spectroscopy can also be used to support the diagnosis of MERRF syndrome by showing high levels of lactic acid in the brain [4].

Additional Diagnostic Tests

Other diagnostic tests that may be performed to rule out other conditions or to confirm the diagnosis of MERRF syndrome include:

  • Complete blood count, serum electrolytes, liver function tests, blood urea nitrogen, creatinine, lactate, and pyruvate [5]
  • Genetic testing to identify mutations in the mitochondrial gene called MT-TK [6]

References

[1] Context 1: MERRF syndrome is diagnosed based on clinical findings and molecular genetic testing.

[2] Context 2: The diagnosis of MERRF syndrome relies on the demonstration of abnormal lactate accumulation in blood or, more often, in the cerebrospinal fluid or MRI brain spectroscopy, and on the muscle biopsy, which reveals the presence of cytochrome c oxidase negative muscle fibers and ragged red fibers.

[3] Context 8: Ragged-red fibers (a characteristic microscopic abnormality observed in muscle biopsy of patients with MERRF and other mitochondrial disorders); Additional diagnostic tests may include imaging studies such as MRI brain spectroscopy.

[4] Context 9: Magnetic resonance spectroscopy (MRS) shows high levels of lactic acid, which further complements the MERRF diagnosis. Muscle biopsy of red-ragged fibres is an essential diagnostic test for MERRF syndrome.

[5] Context 4: Screening patients for MERRF should begin with routine blood tests including complete blood count, serum electrolytes, liver function tests, blood urea nitrogen, creatinine, lactate, and pyruvate.

[6] Context 15: Approximately 90% of cases of MERRF are due to MT-TK mutations.

Additional Diagnostic Tests

  • Imaging Studies
  • Muscle Biopsy
  • Molecular Genetic Testing
  • Complete blood count, serum electrolytes, liver function tests, blood urea nitrogen, creatinine, lactate, and pyruvate
  • Genetic testing to identify mutations in the mitochondrial gene called MT-TK

Treatment

Treatment Options for MERRF Syndrome

MERRF (Myoclonic Epilepsy with Ragged-Red Fibers) syndrome is a rare mitochondrial disorder that affects the nervous system, muscles, and other organs. While there is no specific treatment for MERRF syndrome, various medications and therapies may help manage its symptoms.

Antiepileptic Drugs

The most common seizure type in MERRF syndrome is myoclonic seizures, which can be challenging to treat. However, several antiepileptic drugs (AEDs) have been

Recommended Medications

  • medications
  • antiepileptic drugs

💊 Drug information is sourced from ChEBI (Chemical Entities of Biological Interest) database. Always consult with a healthcare professional before starting any medication. Click on any medication name for detailed information.

Differential Diagnosis

The differential diagnosis of Myoclonic Epilepsy with Ragged Red Fibers (MERRF) syndrome includes other primary mitochondrial diseases, such as POLG1-related ataxia and MERRF-MELAS overlap syndrome. Additionally, degenerative hereditary cerebellar ataxia, Unverricht-Lundborg disease, Lafora body disease, neuronal ceroid lipofuscinosis, and sialidosis are also considered in the differential diagnosis.

  • Other primary mitochondrial diseases: POLG1-related ataxia [3][4], MERRF-MELAS overlap syndrome [5]
  • Degenerative hereditary cerebellar ataxia [6]
  • Unverricht-Lundborg disease [7]
  • Lafora body disease [8]
  • Neuronal ceroid lipofuscinosis [9]

Additional Information

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