MELAS is Usually an Early Onset Disease Volume 2 - Issue 5

Josef Finsterer*

• Krankenanstalt Rudolfstiftung, Messerli Institute, Veterinary University of Vienna, Vienna, Austria

Received: January 01, 2019;   Published: January 04, 2019

*Corresponding author: Josef Finsterer, Postfach 20, 1180 Vienna, Austria, Europe

DOI: 10.32474/LOJMS.2019.02.000149

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Keywords: mtDNA; Mitochondrial; Mutation; Stroke-Like Episode; Seizure; Stroke-Like Lesion

In a recent article, Fang et al. [1] reported about a Chinese female, pretended to have developed mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) not earlier than at age 63y. We have the following comments and concerns. We do not agree that the patient had developed MELAS not earlier than at age 63y [1]. The patient was of short stature, most likely since childhood. Thus, short stature, a classical manifestation of a mitochondrial disorder (MID), must be regarded as a manifestation of the MID and most likely one of the initial manifestations. Furthermore, the patient suffered from hypoacusis since age 2y [1]. Hearing impairment is also a classical manifestation of a MID. In this line, we should be informed about the onset of diabetes and arterial hypertension. Considering manifestations of a MID other than stroke-like episodes (SLEs), the patient had an early onset MID and not at all a late onset MID.

We also do not agree with the statement that MELAS is the most frequent among the specific MIDs [1]. MELAS is a rare subtype of a MID and frequently missed. However, MIDs in general are frequent or even epidemic, which can be attributed to the frequent occurrence of nonspecific mitochondrial multiorgan disorder syndromes (MIMODSs), which do not fit to one of the specific MIDs tagged with an acronym. A further shortcoming of the study is that the low heteroplasmy rate of 20% in blood lymphocytes does not explain the phenotype and that heteroplasmy rates were not investigated in tissues more severely affected. Thus, we should be informed if heteroplasmy rates were higher in hair follicles, skin fibroblasts, buccal mucosa cells, muscle cells, or urinary epithelial cells. Missing in this respect is an investigation of first-degree relatives for the presence or absence of the mtDNA mutation, since the majority of the MELAS cases is maternally inherited [2]. Since sister and mother had experienced also juvenile “stroke”, maternal inheritance is quite likely.

A further shortcoming is that no ADC-maps were provided. SLEs manifest on imaging as stroke-like lesion (SLLs), which typically present as hyperintensity on DWI and on ADC in a nonvascular distribution [3]. Since SLLs take a variable course and may completely disappear or end up as white matter lesion, laminar cortical necrosis, focal atrophy, cysts, or toenail-sign, we should know if repeated imaging studies were carried out and how the first SLL, 2y prior to presentation, and the second SLL developed over time. Since SLEs are frequently associated with seizures, [4] we should know if the patient ever developed seizures, or if epileptiform discharges in the absence of clinical manifestations were ever recorded on EEG. Knowing if there were seizures or asymptomatic paroxysmal activity on EEG is crucial, as patients with SLE and seizures may profit from administration of antiepileptic drugs during the acute stage of a SLE [5]. It is even speculated that seizure activity is responsible for the development of a SLE [5]. Overall, this interesting case could be more meaningful if the above-mentioned shortcomings would have been addressed.

1. Fang GL, Zheng Y, Zhang YX (2018) Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes in an older adult mimicking cerebral infarction: a Chinese case report. Clin Interv Aging 13: 2421- 2424.
2. Poulton J, Finsterer J, Yu-Wai-Man P (2017) Genetic Counselling for Maternally Inherited Mitochondrial Disorders. Mol Diagn Ther 21(4): 419-429.
3. Kim JH, Lim MK, Jeon TY, Rha JH, Eo H, et al. (2011) Diffusion and perfusion characteristics of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episode) in thirteen patients. Korean J Radiol 12(1): 15-24.
4. Iizuka T, Sakai F, Suzuki N, Hata T, Tsukahara S, et al. (2002) Neuronal hyperexcitability in stroke-like episodes of MELAS syndrome. Neurology 59(6): 816-824.
5. Fryer RH, Bain JM, De Vivo DC (2016) Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-Like Episodes (MELAS): A Case Report and Critical Reappraisal of Treatment Options. Pediatr Neurol 56: 59-61.