MT-ND1 Gene Research Articles

Respiratory Chain Complex I Deficiency in Leber Hereditary Optic Neuropathy: Insights from Ophthalmologic and Molecular Investigations in Tunisia

BackgroundLeber hereditary optic neuropathy (LHON) is a mitochondrial DNA (mtDNA) rare disease due to the pathogenic variant of the NADH dehydrogenase enzyme. LHON is characterized by a sudden central vision loss due to focal degeneration of the retinal ganglion cell layer and optic nerve. Symptoms usually appear between the age of 18 and 35 years. Some individuals present the mtDNA mutations but not presented the LHON clinical features. The heteroplasmic or homoplasmic character of the mutations among patients explains why they develop the disease or not even though they carry the pathogenic variant.MethodsThis study was performed in collaboration with the department of ophthalmology of Farhat Hached Hospital, Sousse, Tunisia. Screening for the common mutations in Mt-ND1 gene (m.3460G > A), Mt-ND4 gene (m.11778G > A) and Mt-ND6 gene (m.14484T > C) was performed in five Tunisian families by standard RFLP PCR, followed by direct sequencing of the entire of these genes. Indeed, bioinformatics tools were used to predict the potential functional impact of the identified mutations on the Human mitochondrial respiratory complex I protein.Resultsone novel p.L601M (m.1413 C > A) and four previously reported mutations were identified in this study including: rs199476112G > A (m.11778G > A); rs202227543G > A (m.14258G > A); rs1603224763 (m.14510 dup) and NC_012920.1: m.3244G > C. In this present report, only one patient was found carrying the primary point mutation (m. 11778G > A). The ophthalmologic findings showing major fundus changes included hyperemic optic discs; disc pseudo-oedema and microangiopathy leading to optic disc atrophy. The analyses of the stability of protein upon identified mutations using DynaMut tool server demonstrated that these variations induce a rigidification in the region where they are located.ConclusionThis is the first Tunisian report of mtDNA mutations identified in Tunisia causing the LHON. The main factors involved in the pathophysiological mechanisms of this disease are genetic, epigenetic, hormonal and environmental influences.

Comprehensive phenotypic assessment of nonsense mutations in mitochondrial ND5 in mice

Mitochondrial dysfunction induced by mitochondrial DNA (mtDNA) mutations has been implicated in various human diseases. A comprehensive analysis of mitochondrial genetic disorders requires suitable animal models for human disease studies. While gene knockout via premature stop codons is a powerful method for investigating the unique functions of target genes, achieving knockout of mtDNA has been rare. Here, we report the genotypes and phenotypes of heteroplasmic MT-ND5 gene-knockout mice. These mutant mice presented damaged mitochondrial cristae in the cerebral cortex, hippocampal atrophy, and asymmetry, leading to learning and memory abnormalities. Moreover, mutant mice are susceptible to obesity and thermogenetic disorders. We propose that these mtDNA gene-knockdown mice could serve as valuable animal models for studying the MT-ND5 gene and developing therapies for human mitochondrial disorders in the future.

Characterization of mitochondrial DNA mutations in colorectal cancer progression by in silico approach and use as potential biomarkers for diagnosis and prognosis

BackgroundMitochondrial DNA variants are significant contributors to cancer progression, as evidenced by numerous findings. This study focuses on characterizing mitochondrial DNA mutations in colorectal cancer progression and their potential as biomarkers.MethodologyNext generation sequencing technology was employed to analyze mitochondrial DNA variants in tumor and adjacent normal tissues from 25 patients with colon/rectal cancer. In silico prediction tools (SIFT, Polyphen2, Mutation Assessor, and SNP&GO) were utilized to assess the pathogenicity of these variants. Additionally, homology modeling of mutated protein structures was conducted, and molecular dynamic simulations were performed to assess the impact of mutation on protein function.ResultsEighteen variants were identified across most tumor tissue samples, located in genes from Complex I, IV, and V. Among the identified variants, the V302M and S461 mutations in the MT-ND5 gene and L137F and L220P mutations in the ATP6 gene were predicted to be deleterious, potentially affecting protein function. 3D structural analysis of both wild-type and mutant proteins of MT-ND5 revealed changes in flexibility for the V302M and S461G mutations. The MT-ATP6 mutations L135F and L220P disrupt the interactions with surrounding residues and affect the overall function of protein. Further changes in protein dynamics of the mutated proteins by molecular dynamic simulations also indicate the effects; the mutations have on protein function.ConclusionMT-ND5 and MT-ATP6 variants could serve as potential biomarkers and drug targets in colorectal cancer. This study underscores the significance of mitochondrial DNA variants in cancer progression.

Potential role of heteroplasmic mitochondrial DNA mutations in modulating the subtype-specific adaptation of oral squamous cell carcinoma to cisplatin therapy

Cancer cells are constantly evolving to adapt to environmental changes, particularly during exposure to drug treatment. In this work, we aimed to characterize genetic and epigenetic changes in mitochondrial DNA (mtDNA) that may increase the resistance of oral squamous cell carcinoma (OSCC) to cisplatin. We first derived drug-resistant cells from two human OSCC cell lines, namely SAS and H103, by continual cisplatin treatments for about 4 months. To determine mtDNA changes induced by cisplatin, we performed nanopore sequencing and quantitative polymerase chain reaction analysis of mtDNA extracted from the cells pre- and post-treatment. We also assessed the mitochondrial functions of the cells and their capacity to generate intracellular reactive oxygen species (ROS). We found that in the cisplatin-resistant cells derived from SAS, there was a reduction in mtDNA content and significant enrichment of a m.3910G > C mutation in the MT-ND1 gene. However, such changes were not detected in cisplatin-resistant H103 cells. The cisplatin treatment also altered methylation patterns in both SAS and H103 cells and decreased their sensitivity to ROS-induced cytotoxicity. We suggest that the sequence alterations and epigenetic changes in mtDNA and the reduction in mtDNA content could be key drivers of cisplatin resistance in OSCC. These mtDNA alterations may participate in cellular adaptation that serves as a response to adverse changes in the environment, particularly exposure to cytotoxic agents. Importantly, the observed mtDNA changes may be influenced by the distinct genetic landscapes of various cancer subtypes. Overall, this study reveals significant insights into cisplatin resistance driven by complex mtDNA dynamics, particularly in OSCC. This underscores the need for targeted therapies tailored to the genetic profiles of individual OSCC patients to improve disease prognosis.

Evolutionary characteristics of the mitochondrial NADH dehydrogenase subunit 6 gene in some populations of four sympatric Mustela species (Mustelidae, Mammalia) from central Europe.

Selection on or reticulate evolution of mtDNA is documented in various mammalian taxa and could lead to misleading phylogenetic conclusions if not recognized. We sequenced the MT-ND6 gene of four sympatric Mustelid species of the genus Mustela from some central European populations. We hypothesised positive selection on MT-ND6, given its functional importance and the different body sizes and life histories of the species, even though climatic differences may be unimportant for adaptation in sympatry. MT-ND6 genes were sequenced in 187 sympatric specimens of weasels, Mustela nivalis, stoats, M. erminea, polecats, M. putorius, and steppe polecats, M. eversmannii, from eastern Austria and of fourteen allopatric polecats from eastern-central Germany. Median joining networks, neighbour joining and maximum likelihood analyses as well as Bayesian inference grouped all species according to earlier published phylogenetic models. However, polecats and steppe polecats, two very closely related species, shared the same two haplotypes. We found only negative selection within the Mustela sequences, including 131 downloaded ones covering thirteen species. Positive selection was observed on three MT-ND6 codons of other mustelid genera retrieved from GenBank. Negative selection for MT-ND6 within the genus Mustela suggests absence of both environmental and species-specific effects of cellular energy metabolism despite large species-specific differences in body size. The presently found shared polymorphism in European polecats and steppe polecats may result from ancestral polymorphism before speciation and historical or recent introgressive hybridization; it may indicate mtDNA capture of steppe polecats by M. putorius in Europe.

Mitochondrial genes modulate the phenotypic expression of congenital scoliosis syndrome caused by mutations in the TBXT gene

BackgroundCongenital scoliosis (CS) is a spinal disorder caused by genetic-congenital vertebral malformations and may be associated with other congenital defects or may occur alone. It is genetically heterogeneous and numerous genes contributing to this disease have been identified. In addition, CS has a wide range of phenotypic and genotypic variability, which has been explained by the intervention of genetic factors like modifiers and environment genes. The aim of the present study was to determine the possible cause of CS in a Tunisian patient and to examine the association between mtDNA mutations and mtDNA content and CS. MethodsHere we performed Whole-Exome Sequencing (WES) in a patient presenting clinical features suggestive of severe congenital scoliosis syndrome. Direct sequencing of the whole mitochondrial DNA (mtDNA) was also performed in addition to copy number quantification in the blood of the indexed case. In silico prediction tools, 3D modeling and molecular docking approaches were used. ResultsThe WES revealed the homozygous missense mutation c.512A > G (p.H171R) in the TBXT gene. Bioinformatic analysis demonstrated that the p.H171R variant was highly deleterious and caused the TBXT structure instability. Molecular docking revealed that the p.H171R mutation disrupted the monomer stability which seemed to be crucial for maintaining the stability of the homodimer and consequently to the destabilization of the homodimer-DNA complex. On the other hand, we hypothesized that mtDNA can be a modifier factor, so, the screening of the whole mtDNA showed a novel heteroplasmic m.10150T > A (p.M31K) variation in the MT-ND3 gene. Further, qPCR analyses of the patient’s blood excluded mtDNA depletion. Bioinformatic investigation revealed that the p.M31K mutation in the ND3 protein was highly deleterious and may cause the ND3 protein structure destabilization and could disturb the interaction between complex I subunits. ConclusionWe described the possible role of mtDNA genetics on the pathogenesis of congenital scoliosis by hypothesizing that the presence of the homozygous variant in TBXT accounts for the CS phenotype in our patient and the MT-ND3 gene may act as a modifier gene.

Identification of a novel MT-ND3 variant and restoring mitochondrial function by allotopic expression of MT-ND3 gene

Mitochondrial diseases are caused by nuclear, or mitochondrial DNA (mtDNA) variants and related co-factors. Here, we report a novel m.10197G > C variant in MT-ND3 in a patient, and two other patients with m.10191 T > C. MT-ND3 variants are known to cause Leigh syndrome or mitochondrial complex I deficiency. We performed the functional analyses of the novel m.10197G > C variant that significantly lowered MT-ND3 protein levels, causing complex I assembly and activity deficiency, and reduction of ATP synthesis. We adapted a previously described re-engineering technique of delivering mitochondrial genes into mitochondria through codon optimization for nuclear expression and translation by cytoplasmic ribosomes to rescue defects arising from the MT-ND3 variants. We constructed mitochondrial targeting sequences along with the codon-optimized MT-ND3 and imported them into the mitochondria. To achieve the goal, we imported codon-optimized MT-ND3 into mitochondria in three patients with m.10197G > C and m.10191 T > C missense variants in the MT-ND3. Nuclear expression of the MT-ND3 gene partially restored protein levels, complex I deficiency, and significant improvement of ATP production indicating a functional rescue of the mutant phenotype. The codon-optimized nuclear expression of mitochondrial protein and import inside the mitochondria can supplement the requirements for ATP in energy-deficient mitochondrial disease patients.

Alterations in leukocyte telomere length and mitochondrial DNA copy number in benzene poisoning patients.

The aim of this study is to examine and evaluate the impact of benzene poisoning on the relative content of the mitochondrial MT-ND1 gene and telomere length in individuals with occupational chronic benzene poisoning (CBP) compared to a control group. The study will analyze and gather data on the mitochondrial gene content and telomere length in cases of benzene poisoning, and investigate the relationship with blood routine parameters in order to contribute scientific experimental data for the prevention and treatment of CBP. The case group comprised 30 individuals diagnosed with occupational chronic benzene poisoning, whereas the control group consisted of 60 healthy individuals who underwent physical examinations at our hospital concurrently. Blood routine indicators were detected and analyzed, and the PCR method was employed to measure changes in mitochondrial MT-ND1 content and telomere length. Subsequently, a comparison and analysis of the aforementioned indicators was conducted. The case group exhibited a higher mitochondrial gene content (median 366.2, IQR 90.0 rate) compared to the control group (median 101.5, IQR 12.0 rate), with a statistically significant difference between the two groups (P < 0.05). Additionally, the case group demonstrated lower white blood cell levels (3.78 ± 1.387 × 109/L) compared to the control group (5.74 ± 1.41 × 109/L), with a significant difference between the two groups (P < 0.05). Furthermore, the case group displayed lower red blood cell levels (3.86 ± 0.65 × 1012/L) compared to the control group (4.89 ± 0.65 × 1012/L), with a significant difference between the two groups (P < 0.05). The hemoglobin level in the case group (113.33 ± 16.34g/L) was lower than that in the control group (138.22 ± 13.22g/L). There was a significant difference between the two groups (P < 0.05). Platelet levels in the case group (153.80 ± 58.31 × 109/L) is smaller than the control group (244.92 ± 51.99 × 109/L), there was a significant difference between the two groups (P < 0.05). The average telomere length of the normal control group was 1.451 ± 0.475 (rate); The mean telomere length of individuals in the case group diagnosed with benzene poisoning was determined to be 1.237 ± 0.457 (rate). No significant correlation was observed between telomere length and three blood routine parameters, namely white blood cells (WBC), hemoglobin (HB), and platelets (PLT). However, a significant correlation was found between telomere length and red blood cell count (RBC). Additionally, a negative correlation was observed between mitochondrial gene content and white blood cell count (r = - 0.314, P = 0.026), as well as between mitochondrial gene content and red blood cell count (r = - 0.226, P = 0.032). Furthermore, a negative correlation was identified between mitochondrial gene content and hemoglobin (r = - 0.314, P = 0.028), and platelets (r = - 0.445, P = 0.001). Individuals diagnosed with occupational chronic benzene poisoning exhibit a reduction in telomere length and an elevation in the relative content of the mitochondrial MT-ND1 gene. Moreover, a negative correlation is observed between the content of the mitochondrial MT-ND1 gene and four blood routine parameters, namely white blood cells (WBC), red blood cells (RBC), hemoglobin (HB), and platelets (PLT). Consequently, benzene exposure may potentially contribute to the onset of premature aging.

Abstract TP280: Monogenetic Stroke Syndrome Testing in Adults: A Single Center Experience

As access and coverage of genetic testing has increased, it is being used more commonly in adults with strokes. However, no clear guidelines exist for who should undergo genetic testing. Our retrospective review aims to provide guidance in this regard and show our experience. Genetic testing was ordered at our comprehensive stroke center between June 2022 and September 2023. Tests were ordered from GeneDx and genetic material was collected by buccal swab after consent was obtained. Most of the testing was done routinely in the outpatient setting, but was rarely performed inpatient when diagnosis would change acute management. Genetic testing was ordered for 41 patients. Tests ordered included whole exome sequencing, mitochondrial genome sequencing, Marfan syndrome and thoracic aortic aneurysm and dissection panel, Disorders of connective tissues panel and expedited whole genome sequencing. Indications for testing included evaluation of carotid and vertebral dissections, recurrent stroke, cryptogenic stroke, and leukoencephalopathy. The average age of tested patients was 47. Of these patients, 6 had not had a stroke and the testing was ordered to evaluate etiology of vertebral or carotid dissections. Of the 35 patients being evaluated for stroke etiology, 60% had at least one stroke or TIA prior to presentation. Of patients tested, 14 had evidence of dissection in the carotid arteries or vertebral arteries. At the time of analysis, 27 patients had results available, of which 15 had negative results. Positive results with pathogenic variant were seen in 4 patients. Pathologic variants detected included mutations in ABCC6, NOTCH3, MT-TL1, HBB, and MCCACHC genes. Variants of unknown significance were seen in 8 patients. These variants included mutations in MYLK, COL5A1, COL5A2, KRIT1, CCM2, XPR1, MT-CYB, MT-ND4, and MT-ATP6 genes. This study highlights that in the right clinical population, like young patients with recurrent stroke, genetic testing can be helpful to elucidate the etiology of cerebrovascular disease when standard stroke work up is inconclusive. With retrospective review, we aim to provide guidance on indications for genetic testing in adults with stroke and dissection.

Variability of the mitochondrial genome in young Yakut patients with breast cancer

Background. The Sakha (Yakutia) population, the indigenous population of Siberia living in Yakutia, has one of the lowest rates of breast cancer (BC) incidence worldwide. The low BC incidence among the indigenous population of Yakutia has been reported by several authors, but to date the reasons for this phenomenon have not been fully elucidated. It should be noted that the study of factors that reduce the risk of BC is important for its prevention. In several studies, no hereditary BC was found in the Yakuts, and no pathogenic variants of the BRCA1/2 genes associated with hereditary syndromes of breast and ovarian cancers were found. In this regard, we decided to shift the focus to studying the mitochondrial genome of Sakha BC patients using the sequencing method.The purpose of the study was to identify BC-associated mitochondrial genome variants in Sakha patients.Material and Methods. The study included 14 Sakha patients diagnosed with BC. The median age of the patients was 49 years. DNA isolation was performed using phenol-chloroform extraction. DNA libraries were prepared using the Nextera Flex kit (Illumina, USA).Whole-genome sequencing of the mitochondrial genome was performed on a MiSeq instrument (Illuminа, USA). in the Shared Use Centre of the Research Institute of Medical Genetics, Tomsk National Research Centre of the Russian Academy of Sciences. The results obtained in BC patients were compared with those of control subjects.Results. In Sakha women with BC, 159 mitochondrial genome variants that differed from the human mitochondrial DNA (mtDNA) reference sequence (rCRS) were identified. Likely pathogenic variants m.3736G&gt;A of the MT-ND1 gene and m.7279T&gt;C of the MT-CO1 gene were shown to be associated with BC. For the first time, variants predisposing to BC (m.10398A&gt;G; m.14783T&gt;C; m.15043G&gt;A; m.15301G&gt;A) were identified. A distinctive feature of the mitochondrial genome of populations with a low BC incidence is a high level of mtDNA variants with changes in the length of the polycytosine region in the D310 locus.Conclusion. For the first time, mtDNA variants with changes in the length of the polycytosine tract in the D310 locus and likely pathogenic variants m.3736G&gt;A of the MT-ND1 gene and m.7279T&gt;C of the MT-CO1 gene were identified in Sakha BC women. The data obtained indicate that further studies on the role of the identified mtDNA variants in the development of BC using a larger sample of Sakha patients are required.

Employment of Hidden Markov Model in Determining the Quality of Nitrogenous Base Substituted of MT-ND5 gene Sequence in Humans and Mice

Employment of Hidden Markov Model in Determining the Quality of Nitrogenous Base Substituted of MT-ND5 gene Sequence in Humans and Mice

Employment of Hidden Markov Model in Determining the Quality of Nitrogenous Base Substituted of MT-ND5 gene Sequence in Humans and Mice

Employment of Hidden Markov Model in Determining the Quality of Nitrogenous Base Substituted of MT-ND5 gene Sequence in Humans and Mice

Employment of Hidden Markov Model in Determining the Quality of Nitrogenous Base Substituted of MT-ND5 gene Sequence in Humans and Mice

Employment of Hidden Markov Model in Determining the Quality of Nitrogenous Base Substituted of MT-ND5 gene Sequence in Humans and Mice

NARFL deficiency caused mitochondrial dysfunction in lung cancer cells by HIF-1α–DNMT1 axis

NARFL was reported to be a component of cytosolic iron–sulfur cluster assembly pathway and a causative gene of the diffused pulmonary arteriovenous malformations (dPAVMs). NARFL knockout dramatically impaired mitochondrial integrity in mice, which might promote mitochondrial dysfunction and lead to worse survival rate of lung cancer. However, the underlying molecular mechanism of NARFL deficiency in non-small cell lung cancer (NSCLC) is unknown. Knockdown assay was performed in A549 and H1299 cells. The protein levels of HIF-1α and DNMT1 were measured, and then Complex I activity, mtDNA copy numbers and mRNA levels of mtND genes were determined. Cisplatin resistance and cell proliferation were conducted using CCK8 assay. Cell migration and invasion were detected using wound heal assay and transwell assay. Survival analysis of lung cancer patients and KM plotter database were used for evaluating the potential value of NARFL deficiency. NARFL protein was expressed in two cell lines and knockdown assay significantly reduced its levels. Knockdown NARFL increased the protein levels of HIF-1α and DNMT1, and downregulated the mRNA levels of ND genes, mitochondrial Complex I activity, mtDNA copy number, and ATP levels. The mitochondrial dysfunction caused by NARFL deficiency were ameliorated by siHIF-1α and DNMT1 inhibitor. Knockdown NARFL increased the drug resistance and cell migration, and siHIF-1α reversed this effect. Moreover, NSCLC patients with NARFL deficiency had a poor survival rate using a tissue array and KM plotter database, and it would be a target for cancer prognosis and treatment. NARFL deficiency caused dysregulation of energy metabolism in lung cancer cells via HIF-1α–DNMT1 axis, which promoted drug resistance and cell migration. It provided a potential target for treatment and prognosis of lung cancer.

Dangua Fang regulating tricarboxylic acid cycle and respiratory chain and its mechanism in diabetic rats.

To investigate the influence and possible targets of Dangua Fang on tricarboxylic acid (TCA) cycle and respiratory chain to enrich the prescription's mechanism of effective intervention on glycolipid metabolic diseases such as type 2 diabetes. After interventional rats were fed with high glucose and high fat diet ad libitum for 4 weeks, intraperitoneally injected streptozotocin to induce diabetic model. According to blood glucose level,28 diabetic rats were selected and continued to be fed with high glucose and high fat diet, were stratified by body weight, and divided randomly by blood glucose into Model group (was given sterile water by gastric perfusion and injected aquae pro injection intraperitoneally), Dangua group [Dangua liquor 20.5 g·kg-1·d-1 by perfusion and aquae pro injection intraperitoneally], Inhibitor group [sterile water by perfusion and nicotinamide phosphoribosyl transferase (Nampt) specific blocker GEN-617 1.25 mg/kg intraperitoneally], DanInhit group (Dangua liquor and GEN-617 synchronously). Control group were continuously fed with ordinary diet. The intervention was last for 10 weeks. Body weight (BW), liver index (LI), glycosylated hemoglobin (HbA1c), TC, TG, free fatty acids (FFA), creatinine (Cr), and A-ketoglutarate (α-KG), Iso-citric acid (ICA), oxaloacetic acid (OAA) were tested. The cytochrome C oxidase (COX) and Succinate dehydrogenase (SDH) were evaluated by Colorimetry; Nampt protein, Adenosine triphosphate (ATP) synthase (ATPs), Nicotinamide adenine dinucleotide (NAD+)and its reduced (NADH) in liver were measured by enzyme linked immunosorbent assay. The expressions of Nampt and mitochondrialnadhdehydrogenase-1 (mt-ND1) gene in liver was assessed by real-time polymerase chain reaction. Hepatic tissue staining was also completed. The levels of BW, ICA, α-KG and Nampt-mRNA in the Model group are lower than that in the Normal group (P < 0.05), conversely, liver weight, LI, TC, HbA1c, SDH and ATPs, mt-ND1-mRNA, and Nampt protein in the Model group are higher (P < 0.01, P < 0.05). Compared with Model group, the levels of ICA, Nampt-mRNA and Nampt in Dangua group are significantly increased, and FFA obviously raised (P < 0.01 and P < 0.05); liver weight, BW, SDH are obviously lower, and HbA1c decreased significantly (P < 0.01, P < 0.05). TG, FFA and Nampt protein increased in the DanInhit group, TC, TG, BW obviously increased in the Inhibitor group, but SDH is decreased in both the two groups (P < 0.05, P < 0.01). Compared with Dangua group, DanInhib group has the lower levels of ICA, mt-ND1-mRNA, Nampt-mRNA, and the higher level of BW, LI and HbA1c. In the Inhibitor group, ICA and Nampt protein decreased, BW and LI, HbA1c and TG increased (P < 0.01 or P < 0.05). Tissue staining display that, in the model group there is obvious pathologic changes ie: fibrosis, steatosis and inflammatory cell infiltration. Lesions in the Dangua group are mild, and those of Inhibitor group are more obvious than the Model group, and DanInhit group is intermediately affected compared to Dangua group and Inhibitor group. Dangua Fang increases the metabolic flux of TCA cycle and optimizes respiratory chain function by up-regulating Nampt expression.

Mitochondrial DNA 13513G>A Mutation Causing Leber Hereditary Optic Neuropathy Associated With Adult-Onset Renal Failure.

Leber hereditary optic neuropathy (LHON) is one of the more common mitochondrial diseases and is rarely associated with mitochondrial renal disease. We report 3 unrelated patients with a background of adult-onset renal failure who presented to us with LHON and were shown to have a heteroplasmic mitochondrial DNA mutation (m.13513G>A). Retrospective chart review. All 3 patients had a background of chronic renal failure and presented to us with bilateral optic neuropathy (sequential in 2) and were found to have heteroplasmic m.13513G>A mutations in the MT-ND5 gene. Two of the patients were females (aged 30 and 45 years) with chronic kidney disease from their 20s, attributed to pre-eclampsia, one of whom also had diabetes and sudden bilateral hearing loss. One patient was a male (aged 54 years) with chronic kidney disease from his 20s attributed to IgA nephropathy. His mother had diabetes and apparently sudden bilateral blindness in her 70s. Renal biopsy findings were variable and included interstitial fibrosis, acute tubular necrosis, focal segmental glomerulosclerosis, and IgA/C3 tubular casts on immunofluorescence. Mild improvements in vision followed treatment with either idebenone or a combination supplement including coenzyme Q10, alpha-lipoic acid, and B vitamins. Our cases expand the clinical syndromes associated with m.13513G>A to include bilateral optic neuropathy and adult-onset renal disease. This highlights that in patients with bilateral, especially sequential, optic neuropathy a broad approach to mitochondrial testing is more useful than a limited LHON panel. Mitochondrial diseases present a diagnostic challenge because of their clinical and genetic variability.

Morphological and Genetics Support for a Hitherto Undescribed Spotted Cat Species (Genus Leopardus; Felidae, Carnivora) from the Southern Colombian Andes.

In 1989, a skin of a small spotted cat, from the Galeras Volcano in southern Colombia (Nariño Department), was donated to the Instituto Alexander von Humboldt (identification, ID 5857) at Villa de Leyva (Boyacá Department, Colombia). Although originally classified as Leopardus tigrinus, its distinctiveness merits a new taxonomic designation. The skin is distinct from all known L. tigrinus holotypes as well as from other Leopardus species. Analysis of the complete mitochondrial genomes from 44 felid specimens (including 18 L. tigrinus and all the current known species of the genus Leopardus), the mtND5 gene from 84 felid specimens (including 30 L. tigrinus and all the species of the genus Leopardus), and six nuclear DNA microsatellites (113 felid specimens of all the current known species of the genus Leopardus) indicate that this specimen does not belong to any previously recognized Leopardus taxon. The mtND5 gene suggests this new lineage (the Nariño cat as we name it) is a sister taxon of Leopardus colocola. The mitogenomic and nuclear DNA microsatellite analyses suggest that this new lineage is the sister taxon to a clade formed by Central American and trans-Andean L. tigrinus + (Leopardus geoffroyi + Leopardus guigna). The temporal split between the ancestor of this new possible species and the most recent ancestor within Leopardus was dated to 1.2-1.9 million years ago. We consider that this new unique lineage is a new species, and we propose the scientific name Leopardus narinensis.

Progressive Longitudinally Extensive Myelopathy following Stroke in a Patient later found to have m.14484T&gt;C Mutation in Leber’s Hereditary Optic Neuropathy (LHON) gene. (P5-8.008)

<h3>Objective:</h3> To present a unique case of progressive myelopathy following stroke and its relationship to subsequently revealed LHON gene mutation (m.14484T&gt;C). <h3>Background:</h3> Leber’s Hereditary Optic Neuropathy (LHON) is a maternally inherited mitochondrial disease associated with acute or subacute bilateral painless vision loss. LHON can also present with non-optic nerve disorders, including longitudinal myelopathy and increased risk of multiple sclerosis, known as LHON plus or LHON-MS. LHON plus presenting as longitudinal myelopathy without preceding optic neuropathy has been rarely reported. <h3>Design/Methods:</h3> N/A <h3>Results:</h3> A 66-year-old woman with history of hypertension suffered an acute right hemispheric subcortical stroke at age 63 with resultant left sided hemiparesis. Months afterwards she began to experience progressive bilateral sensory symptoms and worsening hemiparesis, initially resembling Brown-Sequard syndrome. MRI demonstrated exuberant Wallerian degeneration of the corticospinal tract from the site of her stroke, extending through the brainstem to contralateral spinal cord. Extensive autoimmune, neoplastic, ischemic, and metabolic workups were largely unrevealing, aside from elevated ANA and vitamin B12 deficiency. Over the ensuing two years symptoms progressed to near-complete sensory loss of the lower extremities, right sided weakness, and ultimately development of orthopnea, intermittent diplopia, and dysphagia. This continued despite trials of high dose steroids and IVIG. MRI demonstrated new lesions in the contralateral medulla, bilateral posterior and lateral columns, and atrophy in previously affected areas. Whole exome sequencing revealed pathogenic homoplasmic m.14484T&gt;C mutation in the MT-ND6 gene. Patient has never endorsed visual loss. <h3>Conclusions:</h3> This case adds to the few reports of myelopathy as the presenting feature of LHON. Unique in our patient is the absence of visual symptomatology after three years of disease onset, possibly expanding the spectrum of pathology resulting from MT-ND6 mutation. <b>Disclosure:</b> Dr. Eszes has nothing to disclose. Dr. Samkoff has nothing to disclose. Ms. Bontrager has received personal compensation in the range of $500-$4,999 for serving as a Speaker with Muscular Dystrophy Association.

Leber Hereditary Optic Neuropathy in a Family of Carriers of MT-ND5 m.13042G>T (A236S) Novel Variant.

A Slovenian three-generation family with 3 individuals with bilateral optic neuropathy and 2 unaffected relatives with a novel homoplasmic missense variant m.13042G > T (A236S) in the ND5 gene is described. A detailed phenotype at initial diagnosis and a follow-up of bilateral optic neuropathy progression is presented for 2 affected individuals. A detailed phenotype analysis with clinical examination in the early and chronic phase with electrophysiology and OCT segmentation is presented. Genotype analysis with full mitochondrial genome sequencing was performed. Two affected male individuals (maternal cousins) had a profound visual loss at an early age (11 and 20 years) with no recovery. The maternal grandmother exhibited bilateral optic atrophy with a history of visual loss at the age 58 years. The visual loss of both affected male individuals was characterized by centrocecal scotoma, abnormal color vision, abnormal PERG N95, and VEP. Later with disease progression, retinal nerve fiber layer thinning was observed on OCT. We observed no other extraocular clinical features. Mitochondrial sequencing identified a homoplasmic novel variant m.13042G > T (A236S) in the MT-ND5 gene, belonging to a haplogroup K1a. Novel homoplasmic variant m.13042G > T (A236S) in the ND5 gene in our family was associated with Leber hereditary optic neuropathy-like phenotype. However, predicting the pathogenicity of a novel ultra-rare missense variant in the mitochondrial ND5 gene is challenging. Genetic counseling should consider genotypic and phenotypic heterogeneity, incomplete penetrance, haplogroup type, and tissue-specific thresholds.

The Interaction between Circulating Cell-Free Mitochondrial DNA and Inflammatory Cytokines in Predicting Human Mental Health Issue Risk in Adolescents: An Explorative Study.

Adolescence is often a challenging time in which psychiatric issues have a strong connection to mental health disorders later in life. The early identification of the problems can reduce the burden of disease. To date, the effective identification of adolescents at risk of developing mental health problems remains understudied. Altogether, the interaction between circulating cell-free mtDNA (ccf-mtDNA) and inflammatory cytokines in adolescents is insufficiently understood regarding experienced mental health difficulties. Our study selected the participants based on the Strength and Difficulty Questionnaire (SDQ) score using the cut-off points of 3 and 18 for the low and the high score groups, respectively. The answers of the SDQ at the age of 12.2-15.7 years contributed to the investigation of (i) whether ccf-mtDNA units are associated with cytokines, and (ii) if an interaction model for predicting risk of mental health issues is observed. We discovered a sex-specific correlation between the screened markers associated with mental health problems in the low and high SDQ score groups among the male participants and in the low SDQ score group among the female participants. The mitochondrial MT-ND4 and MT-CO1 genes correlated significantly with interleukin-12p70 (IL-12p70) in males and with monocyte chemoattractant protein-1 (MCP-1) in females. Due to the nature of the explorative study, the studied markers alone did not indicate statistical significance for the prediction of mental health problems. Our analysis provided new insight into potential plasma-based biomarkers to predict mental health issues.