Impaired nitric oxide production in children with MELAS syndrome and the effect of arginine and citrulline supplementation

Late onset MELAS with m.3243A > G mutation and its association with aneurysm formation

We reported a 53-year-old with late-onset mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) accompanied by aneurysm and large vessel dilations. Most studies have focused on microangiopathy causing stroke-like episodes. We report a case to describe large vessel involvement in clinical considerations, and possible mechanisms of aneurysm formation. We recommended regular angiographic examination for patients with MELAS.

Arginine and citrulline for the treatment of MELAS syndrome

MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) syndrome is a maternally inherited mitochondrial disease with a broad spectrum of manifestations. In addition to impaired energy production, nitric oxide (NO) deficiency occurs in MELAS syndrome and leads to impaired blood perfusion in microvasculature that can contribute to several complications including stroke-like episodes, myopathy, and lactic acidosis. The supplementation of NO precursors, L-arginine and L-citrulline, increases NO production and hence can potentially have therapeutic utility in MELAS syndrome. L-citrulline raises NO production to a greater extent than L-arginine; therefore, L-citrulline may have a better therapeutic effect. The clinical effect of L-citrulline has not yet been studied and clinical studies on L-arginine, which are limited, only evaluated the stroke-like episodes aspect of the disease. Controlled studies are still needed to assess the clinical effects of L-arginine and L-citrulline on different aspects of MELAS syndrome.

Case report: 5 year follow-up of adult late-onset mitochondrial encephalomyopathy with lactic acid and stroke-like episodes (MELAS)

Mitochondrial encephalomyopathy with lactic acid and stroke-like episodes (MELAS) is a multisystem mitochondrial disorder that typically presents in childhood. We describe the follow-up of a patient who was diagnosed with late-onset MELAS at the age of 49. Her clinical course includes sensorineural hearing loss, seizures, and multiple episodes of stroke-like metabolic crises. Molecular genetic testing on whole blood revealed 31% heteroplasmy of a m.3243A > G variant in the mtDNA, the causative variant in approximately 80% of MELAS cases. The original diagnostic criteria for MELAS required the onset of stroke-like episodes prior to 40 years of age but this case and others demonstrate that onset may be delayed in certain individuals. Therefore, MELAS should be included in the differential diagnosis of stroke-like episodes in patients of any age.