MELAS syndrome: Clinical manifestations, pathogenesis, and treatment options

Topic: Risk, prevention and care in population studies

Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is one of the most frequent maternally inherited mitochondrial disorders. MELAS syndrome is a multi-organ disease with broad manifestations including stroke-like episodes, dementia, epilepsy, lactic acidemia, myopathy, recurrent headaches, hearing impairment, diabetes, and short stature. The most common mutation associated with MELAS syndrome is the m.3243A>G mutation in the MT-TL1 gene encoding the mitochondrial tRNA(Leu(UUR)). The m.3243A>G mutation results in impaired mitochondrial translation and protein synthesis including the mitochondrial electron transport chain complex subunits leading to impaired mitochondrial energy production. The inability of dysfunctional mitochondria to generate sufficient energy to meet the needs of various organs results in the multi-organ dysfunction observed in MELAS syndrome. Energy deficiency can also stimulate mitochondrial proliferation in the smooth muscle and endothelial cells of small blood vessels leading to angiopathy and impaired blood perfusion in the microvasculature of several organs. These events will contribute to the complications observed in MELAS syndrome particularly the stroke-like episodes. In addition, nitric oxide deficiency occurs in MELAS syndrome and can contribute to its complications. There is no specific consensus approach for treating MELAS syndrome. Management is largely symptomatic and should involve a multidisciplinary team. Unblinded studies showed that l-arginine therapy improves stroke-like episode symptoms and decreases the frequency and severity of these episodes. Additionally, carnitine and coenzyme Q10 are commonly used in MELAS syndrome without proven efficacy.

Key findings

• The most common mutation associated with MELAS syndrome is the m.3243A>G mutation in the MT-TL1 gene encoding the mitochondrial tRNA(Leu(UUR)).
• The m.3243A>G mutation results in impaired mitochondrial translation and protein synthesis including the mitochondrial electron transport chain complex subunits leading to impaired mitochondrial energy production.
• The inability of dysfunctional mitochondria to generate sufficient energy to meet the needs of various organs results in the multi-organ dysfunction observed in MELAS syndrome.
• Unblinded studies showed that l-arginine therapy improves stroke-like episode symptoms and decreases the frequency and severity of these episodes.

Why it matters

This review describes MELAS syndrome, a maternally inherited mitochondrial disorder whose manifestations include dementia, and explains how the m.3243A>G mutation impairs mitochondrial energy production. It states there is no specific consensus approach, and reports no treatment, cure or prevention for Alzheimer's disease.

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Study details

• Evidence strengthLow

Read the original

• DOI: 10.1016/j.ymgme.2015.06.004
• PubMed: 26095523
• Original source →

May need a subscription OpenAlex found no free copy of the full text (checked 6 Feb 1020), so the publisher may charge for it. The PubMed abstract is free.

@article{elhattab2015-26095523,
  author  = {El-Hattab, A. W. and Adesina, A. M. and Jones, J. and Scaglia, F.},
  title   = {{MELAS syndrome: Clinical manifestations, pathogenesis, and treatment options}},
  journal = {Molecular genetics and metabolism},
  year    = {2015},
  doi     = {10.1016/j.ymgme.2015.06.004},
  pmid    = {26095523},
  url     = {https://doi.org/10.1016/j.ymgme.2015.06.004}
}

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