Suspect MELAS early to prevent unnecessary costs and burdens for the affected

Abstract

With interest we read the article by Trang et al . about a 34 years old female who was diagnosed with mitochondrial encephalopathy, lactic acidosis, and stroke-like episode (MELAS) syndrome upon application of the Hirano criteria. She manifested clinically with short stature, pigmentary retinopathy, hearing loss, lactic acidosis, basal ganglia calcification, dementia, recurrent stroke-like episodes at ages 27 years, 32 years, cerebellar atrophy, and 34 years respectively, and epilepsy [1] . The diagnosis was confirmed by documentation of the m.3243A > G variant [1] . It was concluded that MELAS needs to be delineated from herpes-simplex encephalitis, ischemic stroke, and posterior reversible encephalopathy syndrome [1] . The study is appealing but raises concerns. The first limitation is that no heteroplasmy rates of clinically affected tissues were provided. Knowing heteroplasmy rates is crucial as they may determine the phenotype, the severity, and thus the outcome of the condition [2] . It would be also helpful to know if mtDNA copy number was normal or decreased in the index patient. The second limitation is that the 3 stroke-like lesions (SLLs) were only poorly characterized on imaging. The typical features of a SLL, the morphological equivalent of a strokelike episode on imaging, are hyperintensity on T2/fluidattenuated inversion recovery, diffusion-weighted imaging, and perfusion-weighted imaging, hypointensity on oxygenextraction fraction-MRI, and hypometabolism on FDG-PET [3] . SLLs most frequently originate from the cortex and spread progressively to the subcortical white matter and adjacent cortical areas. MR-spectroscopy frequently depicts an increased lactate peak, which can be confirmed by investigations of the cerebro-spinal fluid (CSF) showing elevated CSF lactate. A third limitation is that the current medication and the treatment for the third SLL, which was correctly identified, was not provided. Knowing the treatment of the acute SLL and the chronic medication is crucial as several drugs can be