MELAS syndrome diagnosed in ICU in a 56-year-old patient presenting with status epilepticus

Resolving complexity in mitochondrial disease: Towards precision medicine

Mitochondrial diseases, caused by mutations in either the nuclear or mitochondrial genomes (mtDNA), are the most common form of inherited neurometabolic disorders. They are remarkably heterogeneous, both in their clinical presentation and genetic etiology, presenting challenges for diagnosis, clinical management and elucidation of molecular mechanism. The multifaceted nature of these diseases, compounded by the unique characteristics of mitochondrial genetics, cement their space in the field of complex disease. In this review we examine the m.3243A>G variant, one of the most prevalent mitochondrial DNA mutations, using it as an exemplar to demonstrate the challenges presented by these complex disorders. Disease caused by m.3243A>G is one of the most phenotypically diverse of all mitochondrial diseases; we outline known causes of this heterogeneity including mtDNA heteroplasmy, mtDNA copy number and nuclear genetic factors. We consider the impact that this has in the clinic, discussing the personalized management of common manifestations attributed to this pathogenic mtDNA variant, including hearing impairment, diabetes mellitus, myopathy, cardiac disease, stroke-like episodes and gastrointestinal disturbances. Future research into this complex disorder must account for this heterogeneity, benefitting from the use of large patient cohorts to build upon current clinical expertise. Through multi-disciplinary collaboration, the complexities of this mitochondrial disease can be addressed with the variety of diagnostic, prognostic, and treatment approaches that are moulded to best fit the needs of each individual patient.

Mitochondrial diseases and status epilepticus

This narrative review focuses on the pathophysiology, diagnosis, and management of status epilepticus in the context of primary mitochondrial disease. Epilepsy is common in mitochondrial disease, reported in >20% of adult cases and 40%-60% of pediatric cohorts. Status epilepticus is less frequently reported and appears to be associated with particular subgroups of mitochondrial disorders, namely defects of the mitochondrial DNA and its maintenance, and disorders of mitochondrial translation and dynamics. Mechanisms underlying mitochondrial status epilepticus are incompletely understood, and may include bioenergetic failure, oxidative stress, immune dysfunction, and impaired mitochondrial dynamics. Treatments tried in mitochondrial status epilepticus include antiepileptic drugs, anesthetic agents, magnesium, high-dose steroids, immune globulins, vagus nerve stimulation, and surgical procedures, all with variable success. The outcome of mitochondrial status epilepticus is extremely poor, and effective therapeutic options have not been reported. Improved understanding of the mechanisms underpinning mitochondrial status epilepticus is needed in order to develop more effective treatments.

A Mitochondrial Disorder in a Middle Age Iranian Patient: Report of a Rare Case

Introduction

Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) can involve multiple systems and cause stroke-like episodes and status epilepticus.

Case Presentation

A 48-year-old female with history of early fatigability, migraine-type headaches, and bilateral sensory-neural hearing loss presented 3 episodes of serial seizures. On admission she was affected by Wernicke aphasia and, then, right hemiparesis. Investigations showed elevated arterial lactate and ragged red fibers on muscle biopsy.

Conclusion

Though more commonly diagnosed during childhood, some cases of adult-onset MELAS syndrome are reported. This syndrome should be considered in patients with stroke-like events in adults without cerebrovascular risk factors and difficult-to-treat seizures.

Mitochondrial disease: genetics and management

Mitochondrial disease is one of the most common groups of genetic diseases with a minimum prevalence of greater than 1 in 5000 in adults. Whilst multi-system involvement is often evident, neurological manifestation is the principal presentation in most cases. The multiple clinical phenotypes and the involvement of both the mitochondrial and nuclear genome make mitochondrial disease particularly challenging for the clinician. In this review article we cover mitochondrial genetics and common neurological presentations associated with adult mitochondrial disease. In addition, specific and supportive treatments are discussed.