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We retrospectively reviewed the data of 140 female pediatric patients with rare mitochondrial diseases (MDs) confirmed using muscle biopsy. We evaluated patients who were diagnosed with central precocious puberty (PP) with early pubertal development to determine whether PP is a clinical manifestation of MDs. We also examined the clinical, auxiological, laboratory, and radiological parameters after 1 year of gonadotropin-releasing hormone treatment for central PP. Among the 140 girls with MDs, 29 had early pubertal development and underwent endocrine evaluation. Ten (7.1%) patients were diagnosed with central PP; the prevalence of central PP was higher than was that previously thought. Patients with central PP exhibited bone age advancement over 1 year and increased sex hormone levels despite their young age at diagnosis. Serum estradiol levels were significantly higher in younger patients than in older patients (P = 0.004). Patients with central PP treated with gonadotropin-releasing hormone had favorable outcomes, and their pubertal development was suppressed for 1 year.Conclusion: Central PP may be a manifestation of endocrine dysfunction in young girls with MDs. What is Known: • The general characteristics of mitochondrial diseases include developmental delays and retarded growth. • Precocious puberty has rarely been suggested as a clinical manifestation of mitochondrial diseases. What is New: • Among the 140 girls with mitochondrial diseases, 10 (7.1%) were diagnosed with central precocious puberty. • Serum estradiol levels were significantly higher in younger patients than in older patients.

Purpose: Previous studies have shown that neurologic symptoms are dominant in patients with mitochondrial diseases, and most of these patients have seizure-related disorders. The epileptic classification of these patients as Lennox-Gastaut syndrome (LGS) is as high as 25%. This study aimed to investigate the clinical manifestations, diagnoses, treatments, and epilepsy in LGS, which is associated with mitochondrial disease., Materials and Methods: A retrospective study was conducted on 372 patients who were diagnosed with mitochondrial disease between 2006 and 2016. Of these 372 patients, 40 patients diagnosed with LGS were selected, and they were classified into two groups based on the history of West syndrome. Patient characteristics were reviewed, and associations between clinical factors and outcomes after the treatment were analyzed., Results: The proportion of individuals with mitochondrial disease with LGS with a history of West syndrome was 32.5%. Among the patients with mitochondrial disease with LGS, neonatal seizure ( p =0.029), seizure as the first symptom ( p =0.018), and generalized paroxysmal fast activity frequency on electroencephalogram ( p =0.018) in the group with a history of West syndrome were statistically significantly high. The first symptom onset (0.6±0.4 yrs vs. 1.6±0.9 yrs, p =0.003) and first seizure onset (0.9±0.7 yrs vs. 3.9±3.1 yrs, p <0.001) were significantly faster in patients with a history of West syndrome., Conclusion: Close monitoring of the medical condition and early intervention might improve the prognosis of individuals with mitochondrial disease with LGS and a history of West syndrome., Competing Interests: The authors have no potential conflicts of interest to disclose., (© Copyright: Yonsei University College of Medicine 2019.)

Purpose: Children with mitochondrial disease (MD) have clinical phenotypes that are more severe than those found in adults. In this study, we assessed cardiac function in children with MD using conventional and advanced echocardiographic measurements, explored any unique patterns present, and investigated the development of early cardiomyopathy (CMP)., Materials and Methods: We retrospectively reviewed the medical records of 33 children with MD. All patients underwent transthoracic echocardiography with conventional and advanced myocardial analysis. We compared all data between patients and an age-matched healthy control group., Results: Conventional echocardiographic diastolic measurements of mitral E, E/A, and tissue Doppler E' were significantly lower and E/E' was significantly higher in children with MD, compared with the measurements from the control group. There was no significant difference in longitudinal and radial strain between the groups. Circumferential strain in the endocardium (p=0.161), middle myocardium (p=0.008), and epicardium (p=0.042) were lower in patients, compared to the values in controls. Circumferential strain was correlated with E' (p<0.01, r>0.60)., Conclusion: In children with MD, myocardial circumferential strain may develop early in all three layers, even with normally preserved longitudinal and radial strain. This may be an early diagnostic indicator with which to predict CMP in this patient population., Competing Interests: The authors have no financial conflicts of interest., (© Copyright: Yonsei University College of Medicine 2018)

We investigated the effects of enteral tube feeding in Korean children with mitochondrial diseases. We performed a retrospective chart review of 68 paediatric patients with mitochondrial diseases on enteral tube feeding at a tertiary referral centre. The outcome of enteral nutrition was evaluated by decrease in gastrointestinal (GI) symptoms, weight gain, and increase in developmental quotient (DQ) among patients with data available. Among 68 patients, 56 (82%) were on gastrostomy and 12 (18%) were on prolonged nasogastric (NG) tube feeding. Decrease of GI symptoms was present in 37 of 48 patients (77%). Weight gain was present in 18 of 64 patients (28%) and was more prominent in the gastrostomy group (n = 17/54, 32%). Increase in DQ was similar between the NG tube and gastrostomy groups (total n = 10/48, 21%). Complications occurred in 42% (n = 5/12) of the NG tube group and 64% (n = 36/56) of the gastrostomy group. They varied in range, from mild to severe. Most complications were minor; there were 5 cases (9%) requiring gastrostomy removal or additional procedure and 2 cases (4%) of gastrostomy-related morbidity. Our results show that in paediatric patients with mitochondrial diseases, enteral tube feeding could help enhance quality of life by relieving GI symptoms, ameliorate growth failure and enhance development.

Background: Little is known regarding the neuropsychological profiles of pediatric patients with mitochondrial diseases or their parents, information that is crucial for improving the quality of life (QOL) for both patients and parents. We aimed to delineate neurodevelopment and psychological comorbidity in children with mitochondrial diseases in the preliminary investigation of adequate intervention methods, better prognoses, and improved QOL for both patients and parents., Methods: Seventy children diagnosed with mitochondrial diseases were neuropsychologically evaluated. Neurocognitive (development, intelligence) and psychological (behavior, daily living function, maternal depression, parenting stress) functions were analyzed. Clinical variables, including the first symptom, epileptic classification, organ involvement, lactic acidosis, brain magnetic resonance imaging findings, muscle pathology, biochemical enzyme assay results, and syndromic diagnosis of mitochondrial diseases, were also reviewed., Results: Prediagnostic assessments indicated that cognitive and psychomotor developments were significantly delayed. Group mean full scale intelligence quotient (IQ) scores indicated mild levels of intellectual disability, borderline levels of verbal IQ impairment, and mild levels of intellectual disability on performance IQ. Many children exhibited clinically significant levels of behavioral problems, whereas mothers of children with mitochondrial diseases exhibited significant increases in parenting stress relative to mothers of healthy children. Furthermore, 65% of mothers exhibited significant levels of depression. Early onset of the first symptoms, diffuse brain atrophy, and drug-resistant epilepsy negatively influenced neurodevelopmental and adaptive functions., Conclusion: Better understanding of the functional levels and profiles of neurodevelopment and psychological comorbidity in children with mitochondrial diseases in the prediagnostic period is essential for adequate support and QOL of children with mitochondrial diseases and their parents., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: We investigated the clinical characteristics that represent risk factors for death in pediatric patients with mitochondrial diseases., Methods: The medical records of mitochondrial disease pediatric patients attended between 2006 and 2015 (n = 221) were reviewed for clinical characteristics, diagnosis, hospitalization, follow-up, survival, and cause of death., Results: The global mortality rate in the cohort was 14% (average age at death, six years). By syndromic diagnosis, the mortality rates were as follows: Leigh syndrome, 17% (15 of 88); mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes, 50% (two of four); and nonspecific mitochondrial disease, 11% (14 of 129). Data regarding 31 patients (17 males) were included in the analysis of cause of death. The age at symptom onset, lead time to diagnosis, duration of illness, and duration of life were 1.8 ± 2.0, 1.7 ± 1.5, 4.3 ± 2.7, and 6.1 ± 2.9 years, respectively. The most common causes of death were sepsis, pneumonia, disseminated intravascular coagulation, and sudden unexpected death (55%, 42%, 29%, and 29%, respectively). Early death (age six years or younger) was associated with lesions in the thalamus, number of organs involved, and Leigh syndrome., Conclusions: Careful monitoring of the medical condition and early intervention are key to improving survival in pediatric patients with mitochondrial disease., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: To describe the ophthalmological manifestations in patients with childhood onset Leigh syndrome (LS) and investigate the correlation between genotypes and phenotypes in patients with LS., Methods: Childhood onset LS was clinically and enzymatically confirmed in a total of 63 patients. Among them, 44 patients who underwent ophthalmologic consultation were included in this study. Patients with LS underwent genotyping for the whole genome of mitochondrial DNA and SURF1 mutations. The clinical demographic and ophthalmologic phenotypes were compared between the good prognosis group and the poor prognosis group., Results: Strabismus (40.9%) was the most frequently observed ophthalmologic manifestation, followed by pigmentary retinopathy (22.5%), optic atrophy (22.5%), ptosis (15.9%), and nystagmus (13.6%). Thirteen patients were exotropes and five patients were esotropes. The mean exodeviation was 29.6±12.5 prism dioptres (PD) and the mean esodeviation was 24.0±8.9 PD. All patients with esotropia reported disease onset at <1 year old. Among 26 patients older than 4 years, eight (30.8%) patients had better than 0.4 in the best eye was noted. Eyelid ptosis was a main presenting sign in four patients (9.1%). Among these patients, two patients had m.13513G>A mutation in the MT-ND5 gene. Age at onset was 2.47±2.06 years in the good prognosis group and 0.92±0.98 years in the poor prognosis group (p=0.002). Serum lactate peak concentration was 3.23±1.36 mmol/L in the good prognosis group and 4.54±2.31 mmol/L in the poor prognosis group (p=0.051)., Conclusions: LS is a group of mitochondrial disorders with variable ophthalmologic manifestations, the most frequent being strabismus in this study. Ptosis could be an initial sign in patients with LS and these patients can be easily misdiagnosed as having juvenile myasthenia gravis., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)

Aims: We evaluated echocardiography and electrocardiography (ECG) results in children with non-specific mitochondrial disease (MD) in order to study early cardiac involvement, a well-known complication of the disease., Methods: Among non-specific MD children whose isolated mitochondrial respiratory chain complex I defect was confirmed by muscle biopsy and satisfied the criteria of MD, 27 who had no cardiac symptoms were evaluated by echocardiography and ECG., Results: Three (11.1%) out of the 27 non-specific MD patients had left ventricular ejection fraction of less than 55% and two of them (7.4%) had fractional shortening of less than 26%. ECG abnormalities were observed in 16 of the non-specific MD patients (59.3%). Prolongation of heart rate-corrected QT interval was seen in 11 (40.7%) and widening of the QRS interval in eight (29.6%). Left ventricular ejection fraction and fractional shortening of the patients were significantly decreased compared with those in the control group while heart rate-corrected QT interval was prolonged in the former group. QRS interval was more widened in non-specific MD patients, but without statistical significance., Conclusion: The potentially severe cardiac involvement observed in our subjects suggests that early cardiac evaluation after confirming the diagnosis of MD and regular follow-up tests should be strongly recommended in children even in cases without typical cardiac manifestations., (© 2012 The Authors. Journal of Paediatrics and Child Health © 2012 Paediatrics and Child Health Division (Royal Australasian College of Physicians).)

Mitochondrial disease is an energy metabolic disorder with various organ involvement. Iron is widely known to be one of the most important nutriments required for normal brain development and several essential metabolic functions. We retrospectively studied the laboratory data on iron deficiency (ID) in 69 children with mitochondrial respiratory chain complex (MRC) defects by biochemical enzyme assay using muscle tissue. We analyzed the differences between groups of mitochondrial disease based on the presence of ID. ID has higher prevalence in children with mitochondrial disease than in the normal population. There were 6 (9%) patients with low hemoglobin, 12 (17%) with low serum ferrtin, and 22 (32%) with low transferrin saturation levels among children with MRC defects. In comparisons between the ID and the non-ID group of MRC-defect patients, the frequency of MRC I defect was significantly higher in the ID group while that of MRC IV defect was higher in the non-ID group. Abnormal brain magnetic resonance imaging (MRI) findings were more frequently detected in the ID group. The incidence of failure to thrive and gastrointestinal symptoms were significantly higher in the ID group. Early diagnosis and proper treatment of ID are recommended. Especially in cases with risk factors such as failure to thrive or gastrointestinal manifestation, active evaluation of ID should be encouraged.

A child's health inevitably affects the parents' psychologic health and quality of life, especially for mothers of disabled children. Caregiver burden and health-related quality of life were investigated in mothers of children with mitochondrial disease, compared with mothers of children with intractable epilepsy. Mothers of children with mitochondrial disease (n = 33) and intractable epilepsy (n = 32) were recruited. The Zarit Burden Inventory, the Medical Outcomes Short Form 36, short version of the World Health Organization Quality of Life, Beck Depression Inventory, and Beck Anxiety Inventory were administered to all participants. Except for duration of illness and number of previous hospitalizations, there was no significant difference in recorded variables between the two groups. Mothers of children with mitochondrial disease had significantly higher caregiver burden and poorer health-related quality of life, particularly related to role limitations, vitality, and mental health. They also had greater levels of depression and anxiety. After adjustment for all covariates, caregiver anxiety was the most important factor affecting overall caregiver burden. With mitochondrial disease, the possibility of maternal inheritance and scarcity of information about the disease might increase anxiety and thus eventually also the caregiver burden. Accurate information about rare diseases provided to caregivers could be helpful in reducing their anxiety., (Copyright 2010 Elsevier Inc. All rights reserved.)

Ohtahara syndrome (OS) is known as an intractable epileptic syndrome in neonatal and early infantile period, differentiated from early myoclonic encephalopathy (EME) in its etiology. We report a patient with OS associated with mitochondrial respiratory chain complex (MRC) I defect. With ketogenic diet and mitochondrial cocktail therapy, seizures were completely controlled and suppression-burst patterns disappeared 3 months after starting treatment. It is suggested that OS could be caused by specific metabolic disorder such as MRC defect and the intensive therapies including ketogenic diet, vitamin and coenzyme therapy and antioxidant treatment might be helpful for some patients.

Aim: Mitochondrial disease is a heterogeneous disorder entity induced by defects in mitochondrial respiratory chain complex (MRC). A significant portion of patients with MRC defect will not conform to a specific, known syndrome. We have analysed the clinical features of 108 Korean paediatric patients with non-specific and non-categorized mitochondrial disease., Methods: We retrospectively reviewed the clinical and laboratory features of 108 paediatrics patients with non-specific and non-categorized mitochondrial diseases who showed defects in MRC activity, confirmed by spectrophotometric biochemical enzyme assay of their muscles., Results: Neuromuscular involvement was noted in all patients, with developmental delay and seizure accounting for 92.6% and 77.8% of total patients respectively. Various extraneurological symptoms were observed. Most patients exhibited MRC I defect, accounting for 100 (92.6%) patients. The most common brain magnetic resonance imaging (MRI) finding was diffuse cerebral atrophy. However, in 23.1% of patients, no notable changes were visible on MRI., Conclusions: Mitochondrial respiratory chain complex I defect was the most common finding in this study. Though neuromuscular symptoms predominated, with presence of numerous extraneurological findings, we could not find any novel symptoms that might be unique to this category of mitochondrial disease. But, comparatively, more patients presented with unremarkable birth histories and normal brain MRI findings.

Aim: Mitochondrial disorders with respiratory chain complex defect are known to show a broad spectrum of clinical phenotypes, though their contribution to renal disease has not received much attention. The aim of this study was to evaluate renal function using different markers of the glomerular filtration rate (GFR) in children with mitochondrial respiratory chain complex (MRC) defects., Methods: Twenty-two patients with MRC I defect confirmed by biochemical enzyme assays using muscle tissue, were evaluated for renal function with diethylenetriaminepentaacetic acid (DTPA) renal scintigraphy, urine creatinine clearance, serum creatinine (Scr) and cystatin C (Cys C) levels., Results: All patients showed lower levels within normal range of Scr (0.4-0.7 mg/dL, mean 0.47 mg/dL), and with no significant correlation with DTPA-GFR. Cys C showed significant correlation with DTPA-GFR (p < 0.01) providing higher diagnostic accuracy than creatinine in patients with MRC defect., Conclusion: In mitochondrial disorder with MRC defect, Scr could not fully reflect renal function due to the relatively small body mass of patients. Considering the limited clinical availability of DTPA renal scintigraphy, Cys C should be taken as the first step to evaluate GFR in mitochondrial disorders.

Mitochondrial disorders are a heterogeneous group of disorders affecting energy metabolism that can present at any age with a wide variety of clinical symptoms. We investigated brain magnetic resonance (MR) findings in 40 children with defects of the mitochondrial respiratory chain (MRC) complex and correlated them with the type of MRC defects. Enrolled were 40 children with MRC defects in biochemical enzyme assay of the muscle specimen. Twenty-one children were found to have classical syndromes of mitochondrial disorders and 19 children presented nonspecific mitochondrial encephalomyopathies. Their brain MR imaging findings were retrospectively reviewed and correlated with the biochemical defect in the MRC complex. Children with MRC defects showed various neuroradiologic features on brain MR imaging that resulted from a complex genetic background and a heterogeneous phenotype. Rapid progression of atrophy involving all structures of the brain with variable involvement of deep gray and white matter are the most frequent MR findings in children with MRC defects in both classical syndromes of mitochondrial disorder and nonspecific mitochondrial encephalomyopathies. The type of biochemical defect in the MRC complex enzyme did not correlate with brain MR findings in child patients.

Purpose: To determine if defects in mitochondrial respiratory chain enzyme complexes (MRCs) contribute to the etiology of childhood epilepsy., Methods: We reviewed the clinical and laboratory features of 48 epileptic patients (23 male, 25 female) with MRC defects that were confirmed by biochemical assays using muscle biopsies., Results: (1) Thirty-five cases (72.9%) were MRC I deficient, one case (2.1%) was MRC II deficient, 11 cases (22.9%) were MRC IV deficient, and one case (2.1%) had combined MRC I and IV deficiencies. (2) In our clinical diagnosis, there were 10 cases (20.8%) with Leigh disease and one case each with myopathy, encephalopathy, lactic acidosis, stroke-like episodes (MELAS) or Alpers' disease (2.1%). Most of the remaining cases (75.0%) had uncategorized mitochondrial cytopathy with nonspecific encephalopathy. (3) For epileptic classification, there were two cases (4.2%) of Ohtahara syndrome, 10 cases (20.8%) of West syndrome, 12 cases (25.0%) of Lennox-Gastaut syndrome, two cases (4.2%) of Landau-Kleffner syndrome, 14 cases (29.2%) of generalized epilepsy, and eight cases (16.7%) of partial epilepsy. (4) The mean age of seizure onset was 2.68 +/- 2.21 (range: 1 month - 5.5 years). (5) Magnetic resonance imaging (MRI) showed diffuse cortical atrophy in 34 cases (70.8%), basal ganglia signal changes in 18 cases (37.5%) and thalamus signal changes in 12 cases (25.0%). (6) A ketogenic diet produced clinical improvements, including seizure reduction and global functional improvement in 75% of 24 patients., Conclusions: MRC defects are one of the important causes of probably symptomatic childhood epilepsy. A ketogenic diet should be carefully considered for treatment of intractable epilepsy related to MRC defects.

Objectives: This study sought to characterize epileptic phenotypes in children with nonspecific mitochondrial disease (MD) and to evaluate MD diagnostic approaches., Methods: A retrospective analysis of the medical, electroencephalogram, and laboratory records of 142 patients with epilepsy was performed. The patients were evaluated for MD, and 124 patients were included in the final cohort. The MD criteria used included an oral glucose lactate stimulation test (OGLST) and urine organic acid/plasma amino acid (UOA/PAA) assays as metabolic indicators of modified Walker criteria, as suggested by Bernier et al. (Neurology 59:1406-1411, 2002)., Results: Twenty-two patients were classified as having definite MD (9), probable MD (5), possible MD (6), or pyruvate dehydrogenase (PDH) deficiency (3), including one patient which showed a respiratory chain (RC) defect and PDH deficiency. Seven out of eight patients in whom significant RC defects were observed showed complex I defects. In 14 patients, epileptic seizures start at infantile ages. Of 17 patients who substantially presented generalized seizures, 4 patients started with partial seizures. Five patients consistently presented only partial seizures. The OGLST and UOA/PAA assays were useful for a more precise diagnosis of MD, although low positive predictive value of the OGLST was regrettable. No patient was classified as definite MD by Walker's original criteria, but the use of our revised MD criteria resulted in the classification of nine additional patients as definite MD., Conclusions: MD manifested considerable diverse epileptic phenotypes and should be considered in the differential diagnosis of epilepsy in children with unexplained encephalomyopathy and progressive and fluctuating clinical courses.

Purpose: To evaluate the clinical efficacy and safety of the ketogenic diet (KD) for patients with intractable childhood epilepsy and mitochondrial respiratory chain (RC) complex defects., Methods: A retrospective analysis evaluated outcomes in 14 children with intractable epilepsy and RC complex defects who were treated with the classic KD involving a 4:1 lipid to nonlipid ratio (% by weight), but without an initial fast and fluid restriction. Outcome measures included seizure frequency, electroencephalography (EEG) findings, the number of antiepileptic drugs, and adverse reactions., Results: Of the 14 patients, 9 had Complex I defects, 1 had a Complex II defect, 3 had Complex IV defects, and 1 had combined Complex I and IV defects. Two patients with Complex IV defects showed clinical progress compatible with the Leigh disease. The epileptic diagnoses were as follows: 5 patients were diagnosed with infantile spasms, 4 with the Lennox-Gastaut syndrome, 1 with the Landau-Kleffner syndrome, 1 with nonspecific generalized seizure disorder, and 3 with partial seizure disorder. The study found that 7 patients became seizure-free after commencing the KD, three of whom successfully completed the diet without relapse. One patient with a greater than 90% seizure reduction, and 2 patients with seizure reductions between 50% and 90%, remained on the diet. Four patients, including two diagnosed with the Leigh disease, did not show any favorable responses to the diet or ceased the diet due to complications., Conclusions: The KD was a safe and effective therapy for seizures in children with intractable epilepsy and RC complex defects.

Background: Mitochondrial DNA (mtDNA)-associated Leigh syndrome is influenced by mutant pathogenicity and corresponding heteroplasmic loads; however, the manner in which heteroplasmic mutant load affects patient phenotypes and the relationship between mutant types and heteroplasmic mutant loads remain unknown. We aimed to investigate the distribution of the mutant load of different mtDNA mutations in a single-center cohort.Methods: We used next-generation sequencing to confirm mtDNA mutations in 31 patients with Leigh syndrome. Subsequently, we counted the number of mtDNA reads to quantitatively analyze the heteroplasmic mutant load and categorize the patients according to the mtDNA mutations they harbored. Confirmed cases of mtDNA-associated Leigh syndrome were classified according to the mutations observed in six genes and 10 nucleotides.Results: Of the 31 patients with Leigh syndrome, 27 harbored known pathogenic mutations. We discovered that MT-ATP6 was the most commonly mutated gene (n = 13 patients), followed by MT-ND3 (n = 7) and MT-ND5 (n = 4). MT-ATP6 had a significantly higher mutant load than MT-ND3 and MT-ND5 (P < 0.001, each). By contrast, MT-ND5 had a significantly lower mutant load than MT-ND3 (P = 0.007). Notably, the mutation loads varied significantly among patients carrying the MT-ATP6, MT-ND3, and MT-ND5 mutations.Conclusions: Our study illustrated the heteroplasmic diversity and phenotypic expression threshold of mutated mitochondrial genes in mtDNA-associated Leigh syndrome. The results provide promising insights into the genotype-phenotype correlation in mtDNA-associated Leigh syndrome that are expected to guide the development of tailored treatments for Leigh syndrome. [ABSTRACT FROM AUTHOR]

Purpose: Diagnosing Leigh syndrome (LS), a representative mitochondrial disease, remains challenging. Mitochondrial DNA (mtDNA)-associated LS, which is maternally inherited, has relatively well-known genetic variants. We evaluated the usefulness of brain magnetic resonance spectroscopy (MRS) for the initial diagnosis of mtDNA-associated LS using data from LS patients. Methods: The study involved LS patients who visited Gangnam Severance Hospital between 2006 and 2018. Based on patients' clinical findings, genetic evaluations, brain magnetic resonance imaging, and brain MRS findings, 24 mtDNA-associated and 49 gene-negative LS patients were included in the current study. Lactate peaks and decreased N-acetyl aspartate (NAA) peaks in brain MRS were compared between both groups. Results: In total, 11 mtDNA mutation subtypes were detected. Our findings showed a higher proportion of brain MRS abnormalities in mtDNA-associated LS patients than in gene-negative LS patients, but no statistically significant differences were observed between the two groups (lactate peak, P=0.080; decreased NAA peak, P=0.115). Conclusion: Brain MRS is currently limited as an initial diagnostic test for mtDNA-associated LS. However, it may be a useful non-invasive test for the follow-up evaluation of mtDNA-associated LS treatment. Ultra-high-field MRS technology is expected in the future. [ABSTRACT FROM AUTHOR]

Purpose: Magnetic resonance spectroscopy (MRS) is a diagnostic tool used to detect abnormal accumulation of lactate in the brain parenchyma in various metabolic diseases. This study evaluated the clinical roles of brain MRS in the initial assessment of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) caused by impairment of the mitochondrial respiratory chain. Methods: Twenty-five patients with the A3243G mutation among 34 MELAS patients referred to the pediatric neurology clinic of Gangnam Severance Hospital between January 2006 and December 2020 were included. In this retrospective study, demographic, clinical, laboratory (serum lactate and lactate-to-pyruvate ratio), magnetic resonance imaging (MRI), and initial MRS (presence of lactate peak and abnormal N-acetylaspartate [NAA]) data were reviewed. Results: Brain MRI showed cortical lesions in 24 of 25 genetically confirmed A3243G MELAS patients with neurologic symptoms in this study. On MRS, 18 patients (72%) had increased lactate peaks, depicting anaerobic energy metabolism, and 17 patients (68%) had decreased NAA levels, indicating neuronal integrity. Ten patients underwent MRS in the acute stage (within 2 weeks of symptoms). Unlike patients who underwent MRS more than 2 weeks after symptom onset, a lactate peak on MRS was observed in all patients in the acute stage (P=0.011). Conclusion: Elevated lactate peaks in acute cerebral infarctions are highly suggestive of mitochondrial encephalopathy. MRS alone is insufficient to diagnose MELAS, but it is valuable as a noninvasive supplemental diagnostic tool in combination with genetic testing. [ABSTRACT FROM AUTHOR]