Symmetric DWI hyperintensities in CMT1X patients after SARS-CoV-2 vaccination should not be classified as stroke-like lesions

The interesting case report by Zhang et al on a 39 years-old male with Charcot-Marie-Tooth disease type 1X has several limitations.The causal relation between the two episodes of asyndesis,dysphagia,and dyspnea 37 d after the second dose of the inactivated severe acute respiratory syndrome-coronavirus-2(SARS-CoV-2)vaccine(Beijing Institute of Biological Products Co.,Ltd.,Beijing,China)remains unproven.SARS-CoV-2 vaccination cannot trigger a genetic disorder.It also remains unsupported that the patient had a stroke-like episode(SLE).SLEs occur in mitochondrial disorders but not in hereditary neuropathies.Because of the episodic nature of the neurological symptoms,it is critical to rule out seizures.Overall,the causal relation between vaccination and the neurological complications remains unsupported and the interpretation of symmetric diffusionweighted imaging lesions on cerebral magnetic resonance imaging should be carefully revised.

Cluster headache as a manifestation of a stroke-like episode in a carrier of the MT-ND3 variant m.10158T>C

In a recent article Fu et al reported about a 52 years old female with a mitochondrial disorder due to the variant m.10158T>C in the mtDNA located gene MT-ND3.The study has a number of shortcomings.The study would particularly profit from providing more data about multisystem disease,from providing the current medication,the cerebro-spinal fluid findings,the detailed phenotypic presentation,and the genotype of first-degree relatives.Since the index patient had experienced recurrent seizures it is crucial to know the current and previous anti-seizure medication as it may strongly determine the outcome.Some of them are mitochondrion-toxic and particularly valproic acid may exhibit fatal side effects.The outcome may also depend on the degree of multisystem involvement why it is crucial to prospectively investigate the patient for subclinical involvement of organs not obviously affected.Additionally,the outcome of the stroke-like lesions on imaging would be interesting to see.Strokelike lesions may completely disappear or may end up as white matter lesion,laminar cortical necrosis,focal atrophy,cyst,or as the so-called toenail sign.There is also a need of discussing more profoundly the imaging findings and their diagnostic significance and to investigate first degree relatives of the index patient clinically and genetically.Though highly interesting,the presentation of this case of a mitochondrial disorder lacks clinical and genetic data of the patient and his relatives.Outcome parameters,such as severity of disease,degree of progression,drugs,pathogenicity of the mutation,and multisystem involvement require a profound discussion.

Retinal nerve fiber and ganglion cell layer thinning in hereditary and acquired mitochondrial optic neuropathies

Dear Editor,With interest we read the article by Teng et al[1]about a study of the retinal nerve and ganglion cell layers by means of optic coherence tomography(OCT)in 32 patients with a mitochondrial optic neuropathy(MON).Included were 20 patients with hereditary MON[Leber’s hereditary optic neuropathy(LHON)],12 patients with acquired MON[ethambutol-induced optic neuropathy(EION)],and 41 healthy controls.Retinal nerve fiber layer(RNFL)thickness was reduced in the nasal,superior,temporal,and inferior quadrants in LHON patients but only in the temporal quadrant in the EION patients.Thickness of the retinal ganglion cell layer(RGCL)was similarly reduced in LHON and EION patients.We have the following comments and concerns.

Mitochondrial vasculopathy

Mitochondrial disorders(MIDs)are usually multisystem disorders(mitochondrial multiorgan disorder syndrome)either on from onset or starting at a point during the disease course.Most frequently affected tissues are those with a high oxygen demand such as the central nervous system,the muscle,endocrine glands,or the myocardium.Recently,it has been shown that rarely alsothe arteries may be affected(mitochondrial arteriopathy).This review focuses on the type,diagnosis,and treat-ment of mitochondrial vasculopathy in MID patients.A literature search using appropriate search terms was carried out.Mitochondrial vasculopathy manifests as either microangiopathy or macroangiopathy.Clinical manifestations of mitochondrial microangiopathy include leukoencephalopathy,migraine-like headache,stroke-like episodes,or peripheral retinopathy.Mitochondrial macroangiopathy manifests as atherosclerosis,ectasia of arteries,aneurysm formation,dissection,or spontan-eous rupture of arteries.The diagnosis relies on the documentation and confirmation of the mitochondrial metabolic defect or the genetic cause after exclusion of non-MID causes.Treatment is not at variance compared to treatment of vasculopathy due to non-MID causes.Mitochondrial vasculopathy exists and manifests as micro-or macroangiopathy.Diagnosing mitochondrial vasculopathy is crucial since appropriate treatment may prevent from severe complications.

Are foveal thickness, pit depth, and slopes truly abnormal in unaffected carriers of the LHON variant m.11778G>G?

Dear Editor,We read with interest the article by Liu et al[1]about an optical coherence tomography(OCT)study of five patients(10 eyes)with Leber’s hereditary optic neuropathy(LHON)due to the variant m.11778 G>A in MT-ND4 which were compared with 11 clinically unaffected carriers(22 eyes)of the variant and with 20 healthy controls.

Repurposing the antioxidant and anti-inflammatory agent N-acetyl cysteine for treating COVID-19

Although several considerations have been raised suggesting a beneficial effect of N-acetyl cysteine(NAC)for the treatment of severe acute respiratory syndrome coronavirus 2 infection,there is currently no clinical evidence that NAC truly prevents coronavirus disease 2019(COVID-19),reduces the severity of the disease,or improves the outcome.Appropriately designed clinical trials are warranted to prove or disprove a therapeutic effect of NAC for COVID-19 patients.

Beneficiality of combined levetiracetam, clonazepam for myoclonus in MERRF requires further confirmation

To the Editor: With interest, we read the article by Su et al[1] about the antiepileptic drug (AED) treatment of 17 patients with genetically confirmed myoclonic epilepsy with ragged-red fibers (MERRF) syndrome. It was found that monotherapy with either levetiracetam (LEV), clonazepam (CZP), valproic acid (VPA).

Mortality in mitochondrial encephalomyopathy,lactic acidosis,and stroke-like episodes does not depend on levetirazetam alone

We appreciated reading the article by Zhang et al[1] about a retrospective study of 102 mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) patients with epilepsy in which disability and outcome were assessed (median follow-up: 4 years). Administration of levetirazetam (LEV) was associated with a better outcome compared to other antiepileptic drugs (AEDs).[1] The study has several shortcomings requiring discussion.

Genetic heterogeneity of noncompaction

To the Editor： With interest we read the article by Wu et all on a 53-year male with agenesia of the right lung and left-ventricular hypertrabeculation / noncompaction （LVHT）. The paper raises the following concerns.

Phenotypic and genotypic peculiarities in Chinese patients with Leigh syndrome

To the Editor: With interest we read the article by Yu et al[1] about a retrospective study of 13 pediatric patients with Leigh syndrome from a single center in China collected over a period of 17 years. The authors concluded that patients with ophthalmoplegia, muscle weakness, ataxia, and respiratory insufficiency should be screened for mutations in genes located on the mtDNA.[1] Patients with suspected Leigh syndrome are recommended to undergo determination of cerebrospinal fluid (CSF) lactate and cerebral imaging.[1] We have the following comment and concerns.

Diagnosing Kearns-Sayre Syndrome Requires Genetic Confirmation

To the Editor： With interest, we read the article by Kwon et al. about a single patient with Kearns-Sayre syndrome （KSS）, who successfully and without complications underwent peripheral nerve block for multiple muscle biopsies. We have the following comments and concerns.

Rathbun syndrome(hypophosphatasia)due to the heterozygous variant c.297+5G>A in alkaline phosphatase with unusual phenotype

To the Editor:Hypophosphatasia(HPP)is a musculoskeletal inborn error-of-metabolism caused by variants in alkaline phosphatase(ALPL)with reduced activity of the serum tissue-non-specific alkaline phosphatase,[1]which is predominantly expressed in brain,muscle,bones,liver,and kidneys.[2]Accordingly,HPP is a multi-system disorder affecting bones and more rarely extra-osseus organs.[2]Osseus features of HPP include decreased bone quality,osteoid accumulations,reduced bone-mineralization,increased incidence of fractures,premature closure of sutures,bone deformities,dwarfism,Bechterew disease,early loss of teeth,intracranial hypertension,and prolonged bone healing.[1]Extra-osseous features of HPP include seizures,[3]myopathy,[2]hepatopathy,and renal insufficiency.HPP responds favorably to enzyme replacement therapy with asfotase-α.[1]

Asymmetric parietal and temporal lobe atrophy due to the variant m.8363G>A in transfer ribonucleic acid(Lysine)

To the Editor:With interest,we read the article by Xu et al[1]about a 54-year old man with a multisystem mitochondrial disorder(MID)affecting the brain,ears,and muscle.Clinical manifestations were attributed to the variant m.8363G>A in tRNA(Lys).[1]We have the following comments and concerns.

Is the MT-TN variant m.5703G>A truly causative for myoclonic epilepsy with ragged red fibers syndrome plus?

To the Editor:With interest we read the article by Fu et al[1] about a 35-year-old male patient with late-onset myoclonic epilepsy with ragged red fibers syndrome (MERRF) plus syndrome being attributed to the MT-TN variant m.5703G>A,We have the following comments and concerns.

Parkinson's disease, heart disease and propolis consumption

It is reported that neurodegeneration is a process that is implicated in both neuropharmacological disorders and brain aging [1].Research has shown that natural products have a wide range of pharmacological and biological activities, some of which have the potential for use in the treatment of Parkinson’s disease (PD)[1].

Impaired Hearing in Mitochondrial Disorders

To the Editor： With interest, we read the article reported by Liu et al. about the frequency of central and peripheral auditory system affection in 73 patients with a mitochondrial disorder （MID） due to mitochondrial DNA （rntDNA） point mutations or a single mtDNA deletion. We had the following comments and concerns.

Diagnosis of Kearns-Sayre Syndrome Requires Comprehensive Work-up

To the Editor：With interest,we read the article by Yu et al.[1] about the clinical presentation and central nervous system （CNS） imaging in 19 patients with Kearns-Sayre syndrome （KSS）,of whom 12 were genetically confirmed.We have the following comments and concerns.@@The main disadvantage of the study was that the diagnosis was not genetically confirmed in all patients and mitochondrial DNA （mtDNA） deletion was detected in only 63% patients,[1] What was the reason for seven KSS patients not undergoing genetic testing？Did not all patients undergo muscle biopsy？

Pathogenicity of the Homoplasmic m.8701A〉 G Variant Requires Confirmation

To the Editor： We read with interest the article by Zhu et al. about a family with dilated cardiomyopathy （dCMP） and arterial hypertension （AHT） in four members being attributed to the m.8701A〉G variant in the ATP6 gene. We have the following comments and concerns.

Mitochondrial tRNA Glutamic Acid Variant 14709T〉C Manifesting as Myoclonic Epilepsy with Ragged Red Fibers

We read with interest the case report by Ban et al. about a 17-year-old male with myoclonic epilepsy with ragged red fibers （MERRF） syndrome being attributed to the mitochondrial tRNA glutamic acid （tRNA [Glu]） variant mitochondrial 14709T〉C. The authors claimed that the variant occurred sporadically and has not been reported in association with a MERRF phenotype so far. We have the following comments and concerns.