RESUMEN

BACKGROUND: Anopheles melas is an understudied malaria vector with a potential role in malaria transmission on the Bijagós Archipelago of Guinea-Bissau. This study presents the first whole-genome sequencing and population genetic analysis for this species from the Bijagós. To our knowledge, this also represents the largest population genetic analysis using WGS data from non-pooled An. melas mosquitoes. METHODS: WGS was conducted for 30 individual An. melas collected during the peak malaria transmission season in 2019 from six different islands on the Bijagós Archipelago. Bioinformatics tools were used to investigate the population structure and prevalence of insecticide resistance markers in this mosquito population. RESULTS: Insecticide resistance mutations associated with pyrethroid resistance in Anopheles gambiae s.s. from the Bijagós were absent in the An. melas population, and no signatures of selective sweeps were identified in insecticide resistance-associated genes. Analysis of structural variants identified a large duplication encompassing the cytochrome-P450 gene cyp9k1. Phylogenetic analysis using publicly available mitochondrial genomes indicated that An. melas from the Bijagós split into two phylogenetic groups because of differentiation on the mitochondrial genome attributed to the cytochrome C oxidase subunits COX I and COX II and the NADH dehydrogenase subunits 1, 4, 4L and 5. CONCLUSIONS: This study identified an absence of insecticide-resistant SNPs common to An. gambiae in the An. melas population, but did identify structural variation over insecticide resistance-associated genes. Furthermore, this study presents novel insights into the population structure of this malaria vector using WGS analysis. Additional studies are required to further understand the role of this vector in malaria transmission.

Asunto(s)

RESUMEN

BACKGROUND: Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes and nemaline myopathy are two rare genetic conditions. We report the first case reported in world literature with coexistence of both these rare disorders. CASE PRESENTATION: A 11-year-old previously healthy Sri Lankan male child, product of a nonconsanguineous marriage with normal development presented with acute onset short lasting recurring episodes of right-sided eye deviation with impaired consciousness. In between episodes he regained consciousness. Family history revealed a similar presentation in the mother at 36 years of age. Examination was significant for short stature and proximal upper and lower limb weakness. His plasma and cerebrospinal fluid lactate were elevated. Magnetic resonance imaging brain had evidence of an acute infarction in the right occipital territory. Sanger sequencing for common mitochondrial variants of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes confirmed this diagnosis. Whole exome sequencing revealed pathogenic compound heterozygous variants in NEB gene implicating in coexisting nemaline myopathy. Acute presentation was managed with supportive care, antiepileptics, and mitochondrial supplementation. Currently he is stable on daily supplementation of arginine and limb-strengthening physiotherapy. He is being monitored closely clinically and with serum lactate level. CONCLUSION: Genetic diseases are rare. Coexistence of two genetic conditions is even rarer. Genetic confirmation of diagnosis is imperative for prediction of complications, accurate management, and genetic counseling.

Asunto(s)

RESUMEN

Mitochondrial cytopathies, predominantly MT-TL1 mutations and, to a lesser extent, MT-ND5, have been associated with mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS), manifesting as multi-organ dysfunction. This is just the second instance of MELAS secondary to the pathogenic novel m.13091T>C variant of MT-ND5. Moreover, nephropathy associated with MT-ND5 mutation has only been reported in nine cases so far. A middle-aged man presented in a state of acute confusion with speech difficulty with both receptive and expressive aphasia. He had a background of refractory seizures, chronic atypical migraine, childhood-onset optic neuropathy, and end-stage renal disease requiring renal transplant. During admission, he had episodes of aggression and paranoid beliefs. Magnetic resonance (MR) imaging of the head showed multiple areas of cortical abnormality, unusual for age, including a large frontal infarct crossing arterial boundaries. Cerebrospinal fluid (CSF) protein and lactate were high, whereas, the electroencephalography (EEG) result was normal. Muscle biopsy mitochondrial DNA gene sequencing derived novel MT-ND5 gene variant m.13091T>C p.(Met252Thr). Kidney biopsy previously had shown interstitial fibrosis and tubular atrophy. He was managed as acute ischaemic stroke along with a combination of clobazam, levetiracetam, and eslicarbazepine for seizures. MELAS typically presents with seizures, stroke-like episodes, cortical visual loss, and recurrent migraine headaches. The previous reported case of m.13091T>C mutation followed a similar progression, however, there was no associated nephropathy and normal visual acuity. Kidney transplants in affected patients of MELAS have been associated with a high survival rate. MT-ND5 mutation-associated nephropathy has shown a variable manifestation, either as focal segmental glomerular sclerosis (FSGS) or tubulo-interstitial disease.

RESUMEN

This study reported a case of MELAS syndrome presenting as the initial imaging characteristics of Fahr's syndrome with "near" sudden unexpected death in epilepsy (SUDEP) and lateralized periodic discharges (LPD). The patient, a young boy, experienced loss of consciousness 2 days prior, which was followed by two limb and facial convulsions. He was later found in cardiac arrest during hospitalization, but regained consciousness gradually after receiving cardiopulmonary resuscitation and tracheal intubation. The patient exhibited short stature, intellectual disability, poor sports abilities, and academic performance since childhood, but had no family history. Emergency head computed tomography (CT) revealed high density calcification in bilateral caudate nucleus, lentiform nucleus, thalamus, and dentate nucleus with evidence of an acute process. The patient was transferred to the neurology department where he continued to recover consciousness, though he experienced dysarthria, left limb hemiplegia, and hemiparesthesia. Changes in head magnetic resonance imaging (MRI) findings were noted at admission, 1 month later, and 6 months later. LPD were observed in his video electroencephalogram. The CT urography indicated a narrow left ureteropelvic junction with left hydronephrosis, which was suggestive of ureteropelvic junction obstruction. Ultimately, a diagnosis of near-SUDEP was suspected in this patient, indicating a rare case of MELAS syndrome with near-SUDEP and LPD. The gene tests results revealed the presence of the mitochondrial DNA A3243G mutation, leading to the final diagnosis of MELAS syndrome. This case expands the clinical disease spectrum of the MELAS syndrome.

RESUMEN

Wolff-Parkinson-White (WPW) syndrome is a condition associated with tachycardia due to accessory pathways in the heart, and it is one of the most common causes of tachycardia in infants and children. WPW may also be associated with mitochondrial encephalomyopathy, lactic acidosis, stroke-like episodes (MELAS syndrome) or LEOPARD syndrome (LS). We report a case of pre-excitation WPW syndrome in a 17-year-old man who was brought to the hospital by ambulance following the collapse. WPW syndrome type A was diagnosed from precordial leads. Electrocardiography (ECG) revealed a short PR interval, delta waves, and positive waves with dominant R in all pericardial leads. Blood test results showed an isolated elevated ALT level. Subsequent echocardiography was unremarkable, with an ejection fraction of 55%, apart from septal and inferior wall dyssynchrony. With regard to the past medical history, he had sensorineural deafness (SND) since childhood and had a family history of SND. Consequently, the patient was transferred to the cardiac electrophysiology department at another hospital after consultation and underwent ablation. A successful post-ablation electrocardiogram revealed the resolution of the WPW syndrome signs and post-ablation features, such as peak T waves.

RESUMEN

Mitochondrial DNA (mtDNA) mutations, including the m.3243A>G mutation that causes mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS), are associated with secondary coenzyme Q10 (CoQ10) deficiency. We previously demonstrated that PPARGC1A knockdown repressed the expression of PDSS2 and several COQ genes. In the present study, we compared the mitochondrial function, CoQ10 status, and levels of PDSS and COQ proteins and genes between mutant cybrids harboring the m.3243A>G mutation and wild-type cybrids. Decreased mitochondrial energy production, defective respiratory function, and reduced CoQ10 levels were observed in the mutant cybrids. The ubiquinol-10:ubiquinone-10 ratio was lower in the mutant cybrids, indicating blockage of the electron transfer upstream of CoQ, as evident from the reduced ratio upon rotenone treatment and increased ratio upon antimycin A treatment in 143B cells. The mutant cybrids exhibited downregulation of PDSS2 and several COQ genes and upregulation of COQ8A. In these cybrids, the levels of PDSS2, COQ3-a isoform, COQ4, and COQ9 were reduced, whereas those of COQ3-b and COQ8A were elevated. The mutant cybrids had repressed PPARGC1A expression, elevated ATP5A levels, and reduced levels of mtDNA-encoded proteins, nuclear DNA-encoded subunits of respiratory enzyme complexes, MNRR1, cytochrome c, and DHODH, but no change in TFAM, TOM20, and VDAC1 levels. Alterations in the CoQ10 level in MELAS may be associated with mitochondrial energy deficiency and abnormal gene regulation. The finding of a reduction in the ubiquinol-10:ubiquinone-10 ratio in the MELAS mutant cybrids differs from our previous discovery that cybrids harboring the m.8344A>G mutation exhibit a high ubiquinol-10:ubiquinone-10 ratio.

Asunto(s)

RESUMEN

Mitochondrial disease is a devastating genetic disorder, with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) and m.3243A>G being the most common phenotype and genotype, respectively. The treatment for MELAS patients is still less effective. Here, we performed transcriptomic and proteomic analysis in muscle tissue of MELAS patients, and discovered that the expression of molecules involved in serine catabolism were significantly upregulated, and serine hydroxymethyltransferase 2 (SHMT2) increased significantly in both the mRNA and protein levels. The SHMT2 protein level was also increased in myoblasts with m.3243A>G mutation, which was transdifferentiated from patients derived fibroblasts, accompanying with the decreased nicotinamide adenine dinucleotide (NAD+)/reduced NAD+ (NADH) ratio and cell viability. After treating with SHMT2 inhibitor (SHIN1), the NAD+/NADH ratio and cell viability in MELAS myoblasts increased significantly. Taken together, our study indicates that enhanced serine catabolism plays an important role in the pathogenesis of MELAS and that SHIN1 can be a potential small molecule for the treatment of this disease.

Asunto(s)

Asunto(s)

RESUMEN

Hyperlipidemia is not uncommon in patients with hereditary myopathies who get older and also in several conditions in which it is frequently observed. Thus, using the common cholesterol reducing medications of the stains group could be considered. However, the side effects of these drugs include myalgia, myopathy and rhabdomyolysis typically associated with high serum creatine kinase (CK). Because high CK levels are very frequently found in hereditary myopathies, physicians are reluctant to use statins in such patients. Reviewing the literature about statin side effects in hereditary myopathies does not provide a clear evidence about the true risk of these drugs. This review critically describes the reported cases of statin side effects in several genetic myopathies and suggests some guidelines for conditions that are contra indicated for statin usage (particularly in mitochondrial disorders, metabolic myopathies, myotonic dystrophy type 2). Possible solutions to the dilemma of whether to use statins in hereditary myopathies are discussed (prescribing other cholesterol lowering agents and a carefully monitored treatment initiation of statins).

Asunto(s)

RESUMEN

This study investigates transfer ribonucleic acid (tRNA) conformational dynamics in the context of MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) using solid-state silicon nitride (SiN) nanopore technology. SiN nanopores in thin membranes with specific dimensions exhibit high signal resolution, enabling real-time and single-molecule electronic detection of tRNA conformational changes. We focus on human mitochondrial tRNALeu(UAA) (mt-Leu(UAA)) that decodes Leu codons UUA/UUG (UUR) during protein synthesis on the mt-ribosome. The single A14G substitution in mt-Leu(UAA) is the major cause of MELAS disease. Measurements of current blockades and dwell times reveal distinct conformational dynamics of the wild-type (WT) and the A14G variant of mt-Leu(UAA) in response to the conserved post-transcriptional m1G9 methylation. While the m1G9-modified WT transcript adopts a more stable structure relative to the unmodified transcript, the m1G9-modified MELAS transcript adopts a less stable structure relative to the unmodified transcript. Notably, these differential features were observed at 0.4 M KCl, but not at 3 M KCl, highlighting the importance of experimental settings that are closer to physiological conditions. This work demonstrates the feasibility of the nanopore platform to discern tRNA molecules that differ by a single-nucleotide substitution or by a single methylation event, providing an important step forward to explore changes in the conformational dynamics of other RNA molecules in human diseases.

Asunto(s)

RESUMEN

Background: Patients with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) usually present with multisystemic dysfunction with a wide range of clinical manifestations. When the tests for common mitochondrial DNA (mtDNA) point mutations are negative and the mtDNA defects hypothesis remains, urine epithelial cells can be used to screen the mitochondrial genome for unknown mutations to confirm the diagnosis. Case presentation: A 66-year-old Chinese woman presented with symptoms of MELAS and was initially misdiagnosed with acute encephalitis at another institution. Although genetic analysis of blood lymphocyte DNA was negative, brain imaging, including magnetic resonance imaging, magnetic resonance spectroscopy, and clinical and laboratory findings, were all suggestive of MELAS. Finally, the patient was eventually diagnosed with MELAS with the mtDNA 5783G>A mutation in the MT-TC gene with a urinary sediment genetic test. Conclusion: This case report expands the genetic repertoire associated with MELAS syndrome and highlights the importance that full mtDNA sequencing should be warranted beside the analysis of classical variants when a mitochondrial disorder is highly suspected. Furthermore, urine sediment genetic testing has played a crucial role in the diagnosis of MELAS.

RESUMEN

Purpose: To describe examination and findings in a case of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) with particular focus on the ocular sequelae from diabetes. Observations: Neovascular glaucoma is not a common manifestation of MELAS. Conclusions and Importance: We present a rare case of neovascular glaucoma in a patient with MELAS with a history of diabetes, hearing loss, and macular dystrophy. MELAS should be suspected in patients with this constellation of symptoms.

RESUMEN

This case report presents a description of a hypertrophic left ventricle with reduced ejection fraction in a man in his mid-twenties with clinical, radiologic, and biochemical features of a rare syndrome called mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS). A literature review of this uncommon syndrome and MELAS cardiomyopathy has been conducted.

RESUMEN

MELAS syndrome, characterized by mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes, represents a devastating mitochondrial disease, with the stroke-like episodes being its primary manifestation. Arginine supplementation has been used and recommended as a treatment for these acute attacks; however, insufficient evidence exists to support this treatment for MELAS. The mechanisms underlying the effect of arginine on MELAS pathophysiology remain unclear, although it is hypothesized that arginine could increase nitric oxide availability and, consequently, enhance blood supply to the brain. A more comprehensive understanding of these mechanisms is necessary to improve treatment strategies, such as dose and regimen adjustments; identify which patients could benefit the most; and establish potential markers for follow-up. This review aims to analyze the existing evidence concerning the mechanisms through which arginine supplementation impacts MELAS pathophysiology and provide the current scenario and perspectives for future investigations.

Asunto(s)

RESUMEN

GDF15 (growth differentiation factor 15) is a marker of cellular energetic stress linked to physical-mental illness, aging, and mortality. However, questions remain about its dynamic properties and measurability in human biofluids other than blood. Here, we examine the natural dynamics and psychobiological regulation of plasma and saliva GDF15 in four human studies representing 4,749 samples from 188 individuals. We show that GDF15 protein is detectable in saliva (8% of plasma concentration), likely produced by salivary glands secretory duct cells. Using a brief laboratory socio-evaluative stressor paradigm, we find that psychosocial stress increases plasma (+3.5-5.9%) and saliva GDF15 (+43%) with distinct kinetics, within minutes. Moreover, saliva GDF15 exhibits a robust awakening response, declining by ~40-89% within 30-45 minutes from its peak level at the time of waking up. Clinically, individuals with genetic mitochondrial OxPhos diseases show elevated baseline plasma and saliva GDF15, and post-stress GDF15 levels in both biofluids correlate with multi-system disease severity, exercise intolerance, and the subjective experience of fatigue. Taken together, our data establish that saliva GDF15 is dynamic, sensitive to psychological states, a clinically relevant endocrine marker of mitochondrial diseases. These findings also point to a shared psychobiological pathway integrating metabolic and mental stress.

RESUMEN

T cells have been shown to maintain a lower percentage (heteroplasmy) of the pathogenic m.3243A>G variant (MT-TL1, associated with maternally inherited diabetes and deafness [MIDD] and mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes [MELAS]). The mechanism(s) underlying this purifying selection, however, remain unknown. Here we report that purified patient memory CD4+ T cells have lower bulk m.3243A>G heteroplasmy compared to naïve CD4+ T cells. In vitro activation of naïve CD4+ m.3243A>G patient T cells results in lower bulk m.3243A>G heteroplasmy after proliferation. Finally, m.3243A>G patient T cell receptor repertoire sequencing reveals relative oligoclonality compared to controls. These data support a role for T cell activation in peripheral, purifying selection against high m.3243A>G heteroplasmy T cells at the level of the cell, in a likely cell-autonomous fashion.

Asunto(s)