MT-ND1 Gene Research Articles

Alternations in mitochondrial genome in carcinogenesis of HPV positive cervix

ObjectiveIt is well known that mitochondrial dysfunctions are involved in tumorigenesis. A special interest of scientists is mitochondrial ND1 gene (mtND1). Recently detected mutations in the mtND1 can disrupt the normal activity of complex I and affect oxidative phosphorylation, thus leading to increase reactive oxygen species production. This study was undertaken to determine the alternations in the mtND1 and evaluate their association with development of precancerous lesions and cervical cancer. MethodsIn the study 29 cervical cancer, 28 low grade squamous intraepithelial lesion (L-SIL) and 30 high grade squamous intraepithelial lesion (H-SIL) HPV positive fragments tissue were screened for the presence of mtND1 mutations. ResultsOur study showed that mutations in the mtND1 gene were detected in patients with precancerous stage, as well as cervical cancer. We have identified 12 point mutations in 116 analyzed precancerous and cancer samples HPV positive. Most detected missense mutations were previously described, except one (p. M156K) with Grantham value 95. The lower expression of mRNA ND1 was detected in cervical cancer cases and in all samples in which mtND1 mutations were identified. Our analyses revealed that level of ROS production was higher in cervical cancer tissues and all cases characterized by mtND1 mutations. ConclusionsWe hypothesize that mutations in MT-ND1 observed in H-SIL and cancer could activate cervical carcinogenesis by increased ROS production.

Clostridium perfringens phospholipase C impairs innate immune response by inducing integrated stress response and mitochondrial-induced epigenetic modifications

Clostridium perfringens, a rod-shaped, gram-positive, anaerobic, spore-forming bacterium is one of the most widely occurring bacterial pathogens, associated with a spectrum of diseases in humans. A major virulence factor during its infection is the enzyme phospholipase C encoded by the plc gene, known as Clostridium perfringens phospholipase C (CpPLC). The present study was designed to understand the role of CpPLC in inducing survival mechanisms and mitochondrial-induced epigenetic changes in a human lymphocyte cell culture model. Following exposure to CpPLC, a significant generation of mitochondrial reactive oxygen species was observed, which coincided with the changes in the expression of vital components of MAP/ERK/RTK signaling cascade that regulates the downstream cellular functions. These disturbances further led to alterations in the mitochondrial genome and functioning. This was supported by the observed upregulation in the expression of mitochondrial fission genes Drp1, Fis1, and Mff, and mitochondrial fusion genes MFN1, MFN2, and OPA1 following CpPLC exposure. CpPLC exposed cells showed upregulation of OMA1, DELE1, and HRI genes involved in the integrated stress response (ISR), which suggests that it may induce the ISR that provides a pro-survival mechanism to the host cell. CpPLC also initiated immune patho-physiologic mechanisms including mitochondrial-induced epigenetic modifications through a mitochondrial-ROS driven signaling pathway. Interestingly, epigenetic machinery not only play a pivotal role in lymphocyte homeostasis by contributing to cell-fate decisions but thought to be one of the mechanisms by which intracellular pathogens survive within the host cells. Importantly, the impairment of mtDNA repair among the CpPLC exposed cells, induced alterations within mtDNA methylation, and led to the deregulation of MT-CO1, MT-ND6, MT-ATPase 6, and MT-ATPase8 gene expression profiles that are important for mitochondrial bioenergetics and subsequent metabolic pathways. This was further confirmed by the changes in the activity of mitochondrial electron chain complexes (complex I, II, III, IV and V). The altered mtDNA methylation profile was also found to be closely associated with the varied expression of mitomiRs and their targets. CpPLC exposed cells showed up-regulation of miR24 expression and down-regulation of miR34a, miR150, and miR155, while the increased expression of mitomiR target genes i.e. of K-Ras, MYC, EGFR, and NF-kβ was also observed in these cells. Altogether, our findings provide novel insights into the derailment of redox signaling machinery in CpPLC treated lymphocytes and its role in the induction of survival mechanisms and mitochondrial-induced epigenetic modifications.

The mitochondrial genome sequence of the BS-C-1 cell line is at odds with the reported derivation from Cercopithecus aethiops

The BS-C-1 cell line widely used in virological research was reportedly derived from the African green monkey Cercopithecus (Chlorocebus) aethiops. We used Sanger sequencing to determine the full nucleotide sequence of mtDNA in BS-C-1 cells. The mitochondrial genome in this cell line is 16,456 bp long and has an organization typical of that in other mammalian genomes with 37 genes, including 2 rRNAs, 22 tRNAs, and 13 polypeptide-encoding genes. Surprisingly, this genome is most closely related to that of Chlorocebus pygerythrus, which does not agree with the reported derivation of this cell line from C. aethiops. Another unexpected observation is the presence of mtDNA length heteroplasmy within the MT-ND6 gene, with the variant containing a stretch of 8 Cs encoding a functional gene, whereas the variant containing 9 Cs encodes a frameshifted gene. It is unclear whether the latter variant is nonfunctional or whether it is corrected by programmed translational ribosomal −1 frameshifting. The availability of the full mtDNA sequence for the BS-C-1 cell line should increase its utility by enabling studies on mtDNA transcription and replication.

Analysis of codon usage pattern of mitochondrial ND genes in Platyhelminthes

Codon usage bias (CUB) is the nonrandom usage of synonymous codons in which some codons are more preferred to others.CUB can be determined by mutation pressure and selection. Various approaches have been used to understand the pattern of CUB in the mitochondrial ND (MT-ND or ND) genes involved in complex I of respiratory chain in five different classes of Platyhelminthes as no work was reported yet. The present study revealed that the CUB varies across MT-ND genes and the coding sequences showed the richness of A and T. Correspondence analysis implied the effect of mutational pressure and also the pattern of codon usage was different in different classes of platyhelminthes for MT-ND genes. Highly significant correlation was observed between overall nucleotide composition and its 3rd codon position in most of the homogeneous nucleotides such as A% and A3%, T% and T3%, G% and G3%, C% and C3%, GC% and GC3% and also some significant correlations observed among heterogeneous nucleotides in all the five classes for MT-ND genes suggested the role of mutational pressure as well as natural selection in affecting the CUB. Neutrality plot suggested that the contributions of natural selection and mutational pressure varied across different classes of platyhelminthes and also differed in different MT-ND genes.

The mitochondrial DNA copy number of cumulus granulosa cells may be related to the maturity of oocyte cytoplasm.

The mitochondrial DNA copy number of cumulus granulosa cells may be related to the maturity of oocyte cytoplasm.

Clinical and molecular characterization of pediatric mitochondrial disorders in south of China.

Mitochondrial disorders (MDs) are genetic ailments affecting all age groups. Epidemiological data and frequencies of gene mutations in pediatric patients in China are scarce. This retrospective study assessed 101 patients with suspected MDs treated at the Neurology Department of Children's Hospital, Fudan University, in 2011-2017. Mitochondrial (mtDNA) and nuclear (nDNA) samples were assessed by long-range polymerase chain reaction (PCR)-based whole mtDNA sequencing and whole exome sequencing (WES) for identifying pathogenic mutations. Muscle samples underwent various staining protocols and immunofluorescence for detecting selected proteins. Seventeen mutations in the MT-TL1, MT-COX2, MT-ND4, MT, tRNA TRNE, MT-TN, MT-TK, MT-ATP6, MT-ND6, MT-ND3 and MT-CO3 genes were identified in 39 patients, of which m.3243A > G, m.3303C > T, m.8993T > C/G, m.9176T > C, and m.10191T > C were most common. Mitochondrial myopathy and MELAS were most common for m.3243A > G mutation. Four novel mutations were detected, including m.9478insT, m.5666T > C, m.8265T > C, and m.8380-13600 deletion mutations related to Leigh syndrome, mitochondrial myopathy and KSS, respectively. Thirty-three mutations in the TK2, POLG, IBA57, HADHB, FBXL4, ALDH5A1, FOXRED1, TPK1, NDUFAF5, NDUFAF7, NDUFV1, CARS2, PDHA1, and HIBCH genes were identified in 19 patients, including 23 currently unknown. Higher rates of TK2, POLG, IBA57, and HADHB mutations were found in nDNA-mutated MD compared with the remaining individuals. Besides, IBA57 c.286T > C (p.Y96H), TK2 c.497A > T (p.D166V) founder mutations critically contributed to MDs. Comprehensive genomic analysis plays a critical role in pediatric MD diagnosis. These data summarize the relative frequencies of different gene mutations in a large Chinese population, and identified 23 novel MD-associated nDNA and 4 novel mtDNA mutations.

Mitochondrial transport mediates survival of retinal ganglion cells in affected LHON patients.

The mutations in the genes encoding the subunits of complex I of the mitochondrial electron transport chain are the most common cause of Leber's hereditary optic neuropathy (LHON), a maternal hereditary disease characterized by retinal ganglion cell (RGC) degeneration. The characteristics of incomplete penetrance indicate that nuclear genetic and environmental factors also determine phenotypic expression of LHON. Therefore, further understanding of the role of mutant mitochondrial nicotinamide adenine dinucleotide dehydrogenase subunit proteins and nuclear genetic factors/environmental effects in the etiology of LHON is needed. In this study, we generated human-induced pluripotent stem cells (hiPSCs) from healthy control, unaffected LHON mutation carrier, and affected LHON patient. hiPSC-derived RGCs were used to study the differences between affected and unaffected carriers of mitochondrial DNA point mutation m.11778G > A in the MT-ND4 gene. We found that both mutated cell lines were characterized by increase in reactive oxygen species production, however, only affected cell line had increased levels of apoptotic cells. We found a significant increase in retrograde mitochondria and a decrease in stationary mitochondria in the affected RGC axons. In addition, the messenger RNA and protein levels of KIF5A in the LHON-affected RGCs were significantly reduced. Antioxidant N-acetyl-L-cysteine could restore the expression of KIF5A and the normal pattern of mitochondrial movement in the affected RGCs. To conclude, we found essential differences in the mutually dependent processes of oxidative stress, mitochondrial transport and apoptosis between two LHON-specific mutation carrier RGC cell lines, asymptomatic carrier and disease-affected, and identified KIF5A as a central modulator of these differences.

Multisystem mitochondrial diseases due to mutations in mtDNA-encoded subunits of complex I

BackgroundMaternally inherited complex I deficiencies due to mutations in MT-ND genes represent a heterogeneous group of multisystem mitochondrial disorders (MD) with a unfavourable prognosis. The aim of the study was to characterize the impact of the mutations in MT-ND genes, including the novel m.13091 T > C variant, on the course of the disease, and to analyse the activities of respiratory chain complexes, the amount of protein subunits, and the mitochondrial energy-generating system (MEGS) in available muscle biopsies and cultivated fibroblasts.MethodsThe respiratory chain complex activities were measured by spectrophotometry, MEGS were analysed using radiolabelled substrates, and protein amount by SDS-PAGE or BN-PAGE in muscle or fibroblasts.ResultsIn our cohort of 106 unrelated families carrying different mtDNA mutations, we found heteroplasmic mutations in the genes MT-ND1, MT-ND3, and MT-ND5, including the novel variant m.13091 T > C, in 13 patients with MD from 12 families. First symptoms developed between early childhood and adolescence and progressed to multisystem disease with a phenotype of Leigh or MELAS syndromes. MRI revealed bilateral symmetrical involvement of deep grey matter typical of Leigh syndrome in 6 children, cortical/white matter stroke-like lesions suggesting MELAS syndrome in 3 patients, and a combination of cortico-subcortical lesions and grey matter involvement in 4 patients. MEGS indicated mitochondrial disturbances in all available muscle samples, as well as a significantly decreased oxidation of [1-14C] pyruvate in fibroblasts. Spectrophotometric analyses revealed a low activity of complex I and/or complex I + III in all muscle samples except one, but the activities in fibroblasts were mostly normal. No correlation was found between complex I activities and mtDNA mutation load, but higher levels of heteroplasmy were generally found in more severely affected patients.ConclusionsMaternally inherited complex I deficiencies were found in 11% of families with mitochondrial diseases in our region. Six patients manifested with Leigh, three with MELAS. The remaining four patients presented with an overlap between these two syndromes. MEGS, especially the oxidation of [1-14C] pyruvate in fibroblasts might serve as a sensitive indicator of functional impairment due to MT-ND mutations. Early onset of the disease and higher level of mtDNA heteroplasmy were associated with a worse prognosis.

Leber Hereditary Optic Neuropathy - Idebenone, Hope of Treatment

Leber hereditary optical neuropathy (LHON) is part of the class of optic neuropathies in which the mitochondrial function is impaired and is characterized by a painless, subacute, bilateral decrease of the central vision. We shall present the case of two brothers AM aged 31 and AT aged 40 who were diagnosed with LHON and whom we initiated treatment with idebenone 900 mg / day with monitoring at one month and 6 months. The mitochondrial DNA analysis demonstrated the existence of mutations 11778G>A for the mtND4 gene in both patients. Idebenone is a synthetic benzoquinone, analogue of ubiquinone. We found a slight but significant improvement in the visual field in patient AM at one month of treatment. We have not found another case in the literature with an improvement in vision so fast after this treatment, and this has led us to write this article. Keywords: Leber hereditary optical neuropathy (LHON), idebenone, mutations 11778G>A, mtND4 gene

Mitochondrial and Nuclear Mitochondrial Variants in Allergic Diseases.

The mitochondrial genome encodes core catalytic peptides that affect major metabolic processes within a cell. Here, we investigated the association between mitochondrial DNA (mtDNA) variants and allergic diseases, including atopic dermatitis (AD) and asthma, alongside heteroplasmy within the mtDNA in subjects with allergic sensitization. We collected genotype data from 973 subjects with allergic sensitization, consisting of 632 children with AD, 498 children with asthma, and 481 healthy controls by extracting DNA from their blood samples. Fisher's exact test was used to investigate mtDNA and nuclear DNA variants related to mitochondrial function (MT-nDNA) to identify their association with allergic diseases. Among the 69 mtDNA variants, rs28357671 located on the MT-ND6 gene displayed statistically significant associations with allergic diseases (Bonferroni-corrected P < 7.25E-4), while 6, 4, and 2 genes were associated with allergic sensitization, AD, and asthma, respectively (P < 0.0002), including NLRX1, OCA2, and CHCHD3 among the MT-nDNA genes. Heteroplasmy of mitochondrial DNA associated with allergic sensitization was evaluated in a separate cohort of patients consisting of 59 subjects with allergic sensitization and 52 controls. Heteroplasmy was verified when a patient carried both alleles of a mitochondrial single-nucleotide polymorphism (SNP) when clustered. One of the 134 mitochondrial SNPs showed heteroplasmy at a level of 0.4313 when clustering was applied. The probe sequence located at mitochondrial position 16217 and within the D-loop, which acts as a major control site for mtDNA expression. This is the first study to evaluate the association between mitochondrial DNA variants and allergic diseases. A harmonized effect of genes related to mitochondrial function may contribute to the risk of allergic diseases.

Three rare pathogenic mtDNA substitutions in LHON patients with low heteroplasmy

In this article we present clinical, molecular and biochemical investigations of three patients with LHON caused by rare point substitutions in mtDNA. One patient harbours the known mtDNA mutation (m.13513 G>A), the others have new variants (m.13379 A>G in MT-ND5 gene and m.14597 A>G in MT-ND6 gene, which has never been previously associated with LHON). NGS analysis of a whole mtDNA derived from patient’s blood revealed a low mutation load (24%, 47%, 23% respectively). Our data, including family segregation analysis, measurement of reactive oxygen species (ROS) production and cytotoxic effect of paraquat and high-resolution respirometry, showed that nucleotide variant m.14597 A>G can be classified as pathogenic mutation.

A novel mutation in the mitochondrial MT-ND5 gene in a family with MELAS. The relevance of genetic analysis on targeted tissues

We report the case of two members of the same family with a novel mitochondrial DNA (mtDNA) gene variant in the MT-ND5 gene associated with MELAS syndrome and discuss limitations of genetics studies. The m.13045A > G mutation was detected at very low load in the daughter’s urine cells (5%) and at different levels in the skeletal muscle of both mother (50%) and daughter (84%), being absent in blood, hair and saliva.Our findings suggest that non-invasive genetic assessment in urine cells may not be a sensitive diagnostic method neither a good predictor of disease development in relatives of some families with mtDNA-associated MELAS, particularly if involving MT-ND5 gene.

Frequency and spectrum of MT-TT variants associated with Leber’s hereditary optic neuropathy in a Chinese cohort of subjects

Leber’s hereditary optic neuropathy (LHON) is a maternally inherited eye disease. In our previous investigations, we have reported the spectrum and frequency of mitochondrial MT-ND1, MT-ND4 and MT-ND6 gene in Chinese LHON population. This study aimed to assess the molecular epidemiology of MT-TT mutations in Chinese families with LHON. A cohort of 352 Chinese Han probands lacking the known LHON-associated mtDNA mutations and 376 control subjects underwent molecular analysis of mtDNA. All variants were evaluated for evolutionary conservation, structural and functional consequences. Fifteen variants were identified in the MT-TT gene by mitochondrial genome analysis of LHON pedigrees, which was substantially higher than that of individuals from general Chinese populations. The incidences of the two known LHON-associated mutations, m.15927G > A and m.15951A > G, were 2.27% and 1.14%, respectively. Nine putative LHON-associated variants were identified in 20 probands, translated into 2.1% cases of this cohort. Moreover, mtDNAs in 41 probands carrying the MT-TT mutation(s) were widely dispersed among nine Eastern Asian haplogroups. Our results suggest that the MT-TT gene is a mutational hotspot for these 352 Chinese families lacking the known LHON-associated mutations. These data further showed the molecular epidemiology of MT-TT mutations in Chinese Han LHON pedigrees.

Glutamate Stimulation Dysregulates AMPA Receptors-Induced Signal Transduction Pathway in Leber's Inherited Optic Neuropathy Patient-Specific hiPSC-Derived Retinal Ganglion Cells.

The mitochondrial genetic disorder, Leber’s hereditary optic neuropathy (LHON), is caused by a mutation in MT-ND4 gene, encoding NADH dehydrogenase subunit 4. It leads to the progressive death of retinal ganglion cells (RGCs) and causes visual impairment or even blindness. However, the precise mechanisms of LHON disease penetrance and progression are not completely elucidated. Human-induced pluripotent stem cells (hiPSCs) offer unique opportunities to investigate disease-relevant phenotypes and regulatory mechanisms underlying LHON pathogenesis at the cellular level. In this study, we successfully generated RGCs by differentiation of LHON patient-specific hiPSCs. We modified the protocol of differentiation to obtain a more enriched population of single-cell RGCs for LHON study. Based on assessing morphology, expression of specific markers and electrophysiological activity, we found that LHON-specific hiPSC-derived were more defective in comparison with normal wild-type RGCs. Based on our previous study, whereby by using microarray analysis we identified that the components of glutamatergic synapse signaling pathway were significantly downregulated in LHON-specific RGCs, we focused our study on glutamate-associated α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors. We found that the protein expression levels of the subunits of the AMPA receptor, GluR1 and GluR2, and their associated scaffold proteins were decreased in LHON-RGCs. By performing the co-immunoprecipitation assay, we found several differences in the efficiencies of interaction between AMPA subunits and scaffold proteins between normal and LHON-specific RGCs.

Analysis of Inherited Optic Neuropathies.

Inherited optic neuropathies (IONs) cover a spectrum of clinically and genetically heterogenic conditions. Genetic evaluation of patients with IONs may enable their better clinico-diagnostic assessment and management of the disease. The aim of the present study was to determine the genetic condition related to the phenotype in patients with diverse inherited optic neuropathies. A retrospective study was performed in 12 adults and 8 children of 8 non-related families. Clinical phenotyping, supported by color fundus, FAF, and OCT imaging, was performed. Genetic testing was obtained for all family members suspected for ION. Identification of pathogenic mutations in eight non-related families helped to confirm the diagnosis of ION. Affected from ION were ten patients (eight adults and two children; four women and six men). Bilateral Leber's hereditary optic neuropathy (LHON) was linked to the m.11778G>A mutation in two families (two affected and five carriers). Secondary homoplasmic LHON mutations in MT-ND1 (m.4216T>C) and MT-CO3 genes (m.9804G>A) were confirmed in two families (each one subject, three eyes affected), without detection of a primary LHON mutation. One member presented a picture of right-sited optic neuropathy associated with a c.220C>G mutation in the ACO2 gene and a heterozygous c.185C>T mutation in the LDLR gene. Autosomal dominant optic atrophy was confirmed in three non-related families (five subjects with bilateral ION), where molecular genetic analyses confirmed four different heterozygous mutations in OPA1: c.1847+1G>T; c.2497-1G>A, 297A>G and c.(2983+1_2984-1)_(c.*3211) (2 splicing mutations, 1 missense mutation, and 1 gross deletion encompassing exons 30 and 31). Combining clinics and molecular genetics when evaluating patients with IONs helps in characterizing disease and, therefore, is strongly recommended for such patients.

Novel pathogenic heteroplasmic substitution m.14597 A>G in the MT-ND6 gene in female with Leber’s hereditary optic neuropathy

Novel pathogenic heteroplasmic substitution m.14597 A>G in the MT-ND6 gene in female with Leber’s hereditary optic neuropathy

Investigation of frequent somatic mutations of MTND5 gene in gastric cancer cell lines and tissues

The present study investigated the single nucleotide variants (SNVs) in mitochondrial DNA (mtDNA) of 13 paired gastric cancer tissue samples and seven gastric cancer cell lines using direct sequencing analysis of the MTND5 region. Results showed that nuclear mitochondrial pseudogenes (NUMTs) and mitochondrial copy number affected the detection of the SNV frequency in gastric cancer tissue and cell line samples using high-throughput sequencing technique. The heteroplasmic point mutation C12474T and G12835A happened in AGS and BGC823 cell lines, respectively. A total of seven SNVs were found in three paired gastric cancer tissue samples, including five heteroplasmic point mutations (A12406G, C12705T, T12882C, G12501A, and A12584G) and two homoplasmic point mutations (G12561A and C13590T). Gastric cancer tissue sample 16 exhibited the highest SNVs frequency with four SNVs (np 12406, np 12705, np 12882, and np 12501), whereas no SNVs or SNPs were detected in the tissue sample 4. SNP 12705 turned out to be an SNV in gastric cancer tissue sample 16. SNV 12338 detected by exome sequencing approach appeared to be an SNP in this study.

Ассоциация гетероплазмии мутаций митохондриального генома с ишемической болезнью сердца

Цель исследования. Усовершенствование алгоритма оценки генетической предрасположенности к развитию ишемической болезни сердца (ИБС), инфаркта миокарда (ИМ). Методика. Для оценки диагностической значимости степени гетероплазмии митохондриального было выполнено определение этого показателя у 100 здоровых лиц и 325 больных ИБС, в том числе у 225 больных ИБС с перенесенным инфарктом миокарда. Методом полимеразной цепной реакции в режиме реального времени (ПЦР-РВ) было проанализировано девять мутаций митохондриального генома, которые имеют корреляцию со степенью выраженности каротидного атеросклероза. Результаты. В настоящей работе проведена сравнительная оценка результатов генотипирования образцов ДНК участников исследования без клинических проявлений атеросклероза (условно здоровых лиц) и больных ИБС. В итоге была разработана математическая модель определения генетического риска ишемической болезни сердца, включающая анализ степени гетероплазмии четырех наиболее информативных генетических маркеров (m.15059G&gt;A, m.3256C&gt;T, m.12315G&gt;A и m.13513G&gt;A) и оценку полученных результатов с помощью ряда статистических методов. Данная модель объясняла не менее 60% вариабельности клинических проявлений атеросклероза (таких, как ИБС и ИМ) и не зависела от других факторов риска сердечно-сосудистых заболеваний. Заключение. На основе анализа суммарной мутационной нагрузки митохондриального генома была разработана математическая модель определения генетической предрасположенности к ишемической болезни сердца и инфаркту миокарда. Aim. To improve the algorithm for assessing the genetic predisposition to development of cardiovascular diseases. Methods. To evaluate the diagnostic value of the degree of mitochondrial heteroplasmy, this index was determined for 100 healthy individuals and 325 patients with coronary heart disease (CHD), including 225 CHD patients after myocardial infarction. The method of real-time polymerase chain reaction (RT-PCR) was used to analyze 9 mutations in the mitochondrial genome, which correlated with the extent of carotid atherosclerosis. Results. A mathematical model was developed to determine the genetic risk of CHD based on calculation of the total mutational load in the mitochondrial genome by mtDNA variants m.12315G&gt;A in MT-TL2 gene, m.15059G&gt;A in MT-CYB gene, m.3256C&gt;T in MT-TL1 gene, and m.13513G&gt;A in MT-ND5 gene. This model explained at least 60% of the variability in clinical manifestations of atherosclerosis and did not depend on other cardiovascular risk factors. Conclusion. Based on the analysis of total mutational load in the mitochondrial genome, a method was developed to assess the genetic risk for development of CHD and myocardial infarction.

Accumulation of Mitochondrial DNA Common Deletion Since The Preataxic Stage of Machado-Joseph Disease.

Molecular alterations reflecting pathophysiologic changes thought to occur many years before the clinical onset of Machado-Joseph disease (MJD)/spinocerebellar ataxia type 3 (SCA3), a late-onset polyglutamine disorder, remain unidentified. The absence of molecular biomarkers hampers clinical trials, which lack sensitive measures of disease progression, preventing the identification of events occurring prior to clinical onset. Our aim was to analyse the mtDNA content and the amount of the common deletion (m.8482_13460del4977) in a cohort of 16 preataxic MJD mutation carriers, 85 MJD patients and 101 apparently healthy age-matched controls. Relative expression levels of RPPH1, MT-ND1 and MT-ND4 genes were assessed by quantitative real-time PCR. The mtDNA content was calculated as the difference between the expression levels of a mitochondrial gene (MT-ND1) and a nuclear gene (RPPH1); the amount of mtDNA common deletion was calculated as the difference between expression levels of a deleted (MT-ND4) and an undeleted (MT-ND1) mitochondrial genes. mtDNA content in MJD carriers was similar to that of healthy age-matched controls, whereas the percentage of the common deletion was significantly increased in MJD subjects, and more pronounced in the preclinical stage (p < 0.05). The BCL2/BAX ratio was decreased in preataxic carriers compared to controls, suggesting that the mitochondrial-mediated apoptotic pathway is altered in MJD. Our findings demonstrate for the first time that accumulation of common deletion starts in the preclinical stage. Such early alterations provide support to the current understanding that any therapeutic intervention in MJD should start before the overt clinical phenotype.

Leber’s hereditary optic neuropathy - Case report

LHON = Leber's hereditary optic neuropathy, mtDNA = mitochondrial DNA, VA = visual acuity, CF = count fingers, OCT = optical coherence tomography, RNFL = retinal nerve fiber layer, GCL = ganglion cells layer, MS = multiple sclerosis, MRI = magnetic resonance imaging, MTI = magnetization transfer imaging, MTR = magnetization transfer ratio.