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Mitochondrial 3243 A-->G mutation (MELAS mutation) associated with painful muscle stiffness
M Deschauer1, T Wieser, S Neudecker
1Department of Neurology, Martin-Luther-Universität Halle-Wittenberg, Germany.
Abstract:
The mitochondrial mutation A-->G at nucleotide position 3243 is associated with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and other mitochondrial encephalomyopathies. We found this mutation in a 61-year-old patient who developed at the age of 54 a myopathy with painful muscle stiffness as the predominant symptom. Additionally hypacusis, a mild hemisensory syndrome and impaired glucose tolerance were present. Muscle histopathology showed few ragged red fibers. The mutation was detected heteroplasmatically in DNA from muscle and blood. So far painful muscle stiffness has not been a known phenotype of the 3243 mutation.
Insights
The mitochondrial 3243 A-->G mutation, typically linked to MELAS, presented unusually with painful muscle stiffness in a 61-year-old patient. This case expands the known phenotype of this common mitochondrial disorder.
Area of Science:
- Genetics
- Neurology
- Mitochondrial Diseases
Background:
- The mitochondrial DNA (mtDNA) A-->G mutation at nucleotide position 3243 is a well-established cause of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS).
- Mitochondrial encephalomyopathies are a heterogeneous group of disorders arising from mutations in mitochondrial DNA or nuclear DNA affecting cellular energy production.
Observation:
- A 61-year-old patient presented at age 54 with a myopathy characterized predominantly by painful muscle stiffness.
- Associated symptoms included hearing loss (hypacusis), a mild hemisensory syndrome, and impaired glucose tolerance.
- Muscle biopsy revealed a small number of ragged red fibers, indicative of mitochondrial dysfunction.
Findings:
- The specific mitochondrial mutation A-->G at position 3243 was heteroplasmically detected in both muscle and blood DNA samples from the patient.
- This finding confirms the genetic basis of the observed symptoms.
Implications:
- This case broadens the clinical spectrum associated with the mitochondrial 3243 A-->G mutation, highlighting painful muscle stiffness as a previously unrecognized phenotype.
- Understanding this expanded phenotype is crucial for accurate diagnosis and management of patients with mitochondrial disorders.
- Further research may elucidate the mechanisms underlying the variable expressivity of this common mtDNA mutation.