Browse
Submit Data
Databases
API
Help

Dataset Information

17 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

A novel variant m.8561C>T in the overlapping region of MT-ATP6 and MT-ATP8 in a child with early-onset severe neurological signs.

ABSTRACT: Among mitochondrial diseases, isolated complex V (CV) deficiency represents a rare cause of respiratory chain (RC) dysfunction. In mammalian mitochondrial DNA (mtDNA), MT-ATP6 partly overlaps with MT-ATP8 making double mutations possible, yet extremely rarely reported principally in patients with cardiomyopathy. Here, we report a novel m.8561 C>T substitution in the overlapping region of MT-ATP6 and MT-ATP8 in a child with early-onset ataxia, psychomotor delay and microcephaly, enlarging the clinical manifestations spectrum associated with CV deficiency.

SUBMITTER: Fragaki K

PROVIDER: S-EPMC6879992 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

A novel variant m.8561C>T in the overlapping region of MT-ATP6 and MT-ATP8 in a child with early-onset severe neurological signs.

Fragaki Konstantina K Chaussenot Annabelle A Serre Valerie V Acquaviva Cecile C Bannwarth Sylvie S Rouzier Cecile C Chabrol Brigitte B Paquis-Flucklinger Veronique V

Molecular genetics and metabolism reports 20191121

Among mitochondrial diseases, isolated complex V (CV) deficiency represents a rare cause of respiratory chain (RC) dysfunction. In mammalian mitochondrial DNA (mtDNA), MT-ATP6 partly overlaps with MT-ATP8 making double mutations possible, yet extremely rarely reported principally in patients with cardiomyopathy. Here, we report a novel m.8561 C>T substitution in the overlapping region of MT-ATP6 and MT-ATP8 in a child with early-onset ataxia, psychomotor delay and mic ...[more]

PMID: 31788426

Similar Datasets

The mitochondrial DNA variant m.9032T > C in MT-ATP6 encoding p.(Leu169Pro) causes a complex mitochondrial neurological syndrome.

Project description:Diagnosing complex V deficiencies caused by new variants in mitochondrial DNA is challenging due to the rarity, phenotypic diversity, and limited functional assessments. We describe a child with the m.9032T > C variant in MT-ATP6 encoding p.(Leu169Pro), with primary presentation of microcephaly, ataxia, hearing loss, and lactic acidosis. Functional studies reveal abnormal fragment F1 of complex V on blue native gel electrophoresis. Respirometry showed excessively tight coupling through complex V depressing oxygen consumption upon ADP stimulation and an excessive increase following uncoupling, in the presence of upregulation of mitochondrial biogenesis. These data add evidence about pathogenicity and functional impact of this variant.

| S-EPMC7669648 | biostudies-literature

Clinical Heterogeneity in MT-ATP6 Pathogenic Variants: Same Genotype-Different Onset.

Project description:Human mitochondrial disease exhibits large variation of clinical phenotypes, even in patients with the same causative gene defect. We illustrate this heterogeneity by confronting clinical and biochemical data of two patients with the uncommon pathogenic homoplasmic NC_012920.1(MT-ATP6):m.9035T>C variant in MT-ATP6. Patient 1 presented as a toddler with severe motor and speech delay and spastic ataxia without extra-neurologic involvement. Patient 2 presented in adolescence with ataxia and ophthalmoplegia without cognitive or motor impairment. Respiratory chain complex activities were normal in cultured skin fibroblasts from both patients when calculated as ratios over citrate synthase activity. Native gels found presence of subcomplexes of complex V in fibroblast and/or skeletal muscle. Bioenergetic measurements in fibroblasts from both patients detected reduced spare respiratory capacities and altered extracellular acidification rates, revealing a switch from mitochondrial respiration to glycolysis to uphold ATP production. Thus, in contrast to the differing disease presentation, biochemical evidence of mitochondrial deficiency turned out quite similar. We conclude that biochemical analysis remains a valuable tool to confirm the genetic diagnosis of mitochondrial disease, especially in patients with new gene variants or atypical clinical presentation.

| S-EPMC8834419 | biostudies-literature

Mutations in MT-ATP6 are a frequent cause of adult-onset spinocerebellar ataxia.

Project description:Adult-onset ataxias are a genetically and clinically heterogeneous group of movement disorders. In addition to nuclear gene mutations, sequence changes have also been described in the mitochondrial genome. Here, we present findings of mutation analysis of the mitochondrial gene MT-ATP6. We analyzed 94 patients with adult-onset spinocerebellar ataxia (SCA), including 34 sporadic cases. In all patients, common sequence changes found in SCAs such as repeat expansions and point mutations had been excluded previously. We found pathogenic MT-ATP variants in five of these patients (5.32%), two of whom were sporadic. Four of the five mutations have not previously been described in ataxias. All but one of these mutations affect transmembrane helices of subunit-α of ATP synthase. Two mutations (p.G16S, and p.P18S) disrupt transmembrane helix 1 (TMH1), one mutation (p.G167D) affects TMH5, and another one (p.L217P) TMH6. The fifth mutation (p.T96A) describes an amino acid change in close proximity to transmembrane helix 3 (TMH3). The level of heteroplasmy was either complete or very high ranging from 87 to 99%. The high prevalence of pathogenic MT-ATP6 variants suggests that analysis of this gene should be included in the routine workup of both hereditary and sporadic ataxias.

| S-EPMC8563540 | biostudies-literature

Reversible Valproate-Induced Subacute Encephalopathy Associated With a MT-ATP8 Variant in the Mitochondrial Genome.

Project description:Introduction: There are several reported cases of patients developing motor and cognitive neurological impairment under treatment with valproic acid (VPA). We describe a woman who developed a subacute encephalopathy after VPA intake, harboring a mitochondrial DNA variant, previously described as causing VPA sensitivity in one pediatric patient. Material and Methods: A 65-year old woman developed a progressive, severe neurological deterioration after a 3 month treatment with valproate sodium, 800 mg daily. Magnetic resonance spectroscopy (MRS), muscle histochemical analysis and assay of mitochondrial enzymatic activities, and mitochondrial DNA sequencing were performed. Results: Neurological examination showed drowsiness, vertical gaze palsy, inability to either stand or walk, diffuse weakness, increased tendon reflexes. Blood lactate was increased, EEG showed diffuse theta and delta activity, MRI subcortical atrophy and leukoencephalopathy, MRS marked reduction of the NAA spectrum, with a small signal compatible with presence of lactate. Muscle biopsy evidenced presence of ragged red fibers (20%) and reduced COX reactivity. Assay of the muscle enzymatic activities showed multiple deficiencies of the electron transport chain and reduced ATP production. The mt.8393C>T variant in the MT-ATP8 gene was found in homoplasmy. The patient considerably improved after valproate withdrawal. Conclusion: The variant we found has been reported both as a polymorphism and, in a single patient, as related to the valproate-induced encephalopathy. The present case is the first bearing this mutation in homoplasmy. In case of neurological symptoms after starting VPA therapy, once hyperammonemia and liver failure have been ruled out, mtDNA abnormalities should be considered.

| S-EPMC6125373 | biostudies-literature

Novel mitochondrial mutations in the ATP6 and ATP8 genes in patients with breast cancer.

Project description:The role of the mitochondria in the process of carcinogenesis, mainly oxidative phosphorylation, mostly concerns their participation in the production of free radicals and ATP and in the process of apoptosis. The purpose of this study was to detect potential changes in the genes encoding the subunits 6 and 8 of the ATP synthase and their impact on the enzyme's biochemical properties, structure and function in patients with breast tumors. The tested material was mitochondrial DNA (mtDNA) isolated from specimens of ductal carcinoma (carcinoma ductale) Tp1-2Np0-1Mp0, blood and non-cancerous tissue of mammary gland (control), sampled from 50 patients who had been operated for breast cancer. In the case of missense-type changes in the mtDNA, protein prediction software was used to assess their effect on the biochemical properties of the protein, its structure and function. We identified 8 changes in the ATP6 gene in 36/50 examined breast cancer cell samples and 5 changes in the ATP8 gene (10/50). Most of them were homoplasmic changes of missense type. Four of the changes (A8439C, G8858C, C9130G and T9119G) had not been described in the literature before. The identified mutations and polymorphisms, especially those of missense type, can affect mitochondrial functions, especially if the conservative domain of the protein is concerned. Replacement of 'wild-type' mtDNA by mutated mtDNA can be an important event in carcinogenesis.

| S-EPMC4148381 | biostudies-literature

Stable nuclear expression of ATP8 and ATP6 genes rescues a mtDNA Complex V null mutant.

Project description:We explore the possibility of re-engineering mitochondrial genes and expressing them from the nucleus as an approach to rescue defects arising from mitochondrial DNA mutations. We have used a patient cybrid cell line with a single point mutation in the overlap region of the ATP8 and ATP6 genes of the human mitochondrial genome. These cells are null for the ATP8 protein, have significantly lowered ATP6 protein levels and no Complex V function. Nuclear expression of only the ATP8 gene with the ATP5G1 mitochondrial targeting sequence appended restored viability on Krebs cycle substrates and ATP synthesis capabilities but, failed to restore ATP hydrolysis and was insensitive to various inhibitors of oxidative phosphorylation. Co-expressing both ATP8 and ATP6 genes under similar conditions resulted in stable protein expression leading to successful integration into Complex V of the oxidative phosphorylation machinery. Tests for ATP hydrolysis / synthesis, oxygen consumption, glycolytic metabolism and viability all indicate a significant functional rescue of the mutant phenotype (including re-assembly of Complex V) following stable co-expression of ATP8 and ATP6 Thus, we report the stable allotopic expression, import and function of two mitochondria encoded genes, ATP8 and ATP6, resulting in simultaneous rescue of the loss of both mitochondrial proteins.

| S-EPMC5100594 | biostudies-literature

The m.9143T>C Variant: Recurrent Infections and Immunodeficiency as an Extension of the Phenotypic Spectrum in MT-ATP6 Mutations?

Project description:Pathogenic variants in the MT-ATP6 are a well-known cause for maternally inherited mitochondrial disorders associated with a wide range of clinical phenotypes. Here, we present a 31- year old female with insulin-dependent diabetes mellitus, recurrent lactic acidosis and ketoacidosis recurrent infections with suspected immunodeficiency with T cell lymphopenia and hypogammaglobulinemia as well as proximal tetraparesis with severe muscle and limb pain and rapid physical exhaustion. Muscle biopsy and respiratory chain activities were normal. Single-exome sequencing revealed a variant in the MT-ATP6 gene: m.9143T>C. Analysis of further specimen of the index and mother (segregation studies) revealed the highest mutation load in muscle (99% level of mtDNA heteroplasmy) of the index patient. Interestingly, acute metabolic and physical decompensation during recurrent illness was documented to be a common clinical feature in patients with MT-ATP6 variants. However, it was not mentioned as a key symptom. Thus, we suggest that the clinical spectrum might be expanded in ATP6-associated diseases.

| S-EPMC7348873 | biostudies-literature

Prospective diagnosis of MT-ATP6-related mitochondrial disease by newborn screening.

Project description:Elevated citrulline and C5-OH levels are reported as part of the newborn screening of core and secondary disorders on the Recommended Uniform Screening Panel (RUSP). Additionally, some state laboratory newborn screening programs report low citrulline levels, which may be observed in proximal urea cycle disorders. We report six patients who were found on newborn screening to have low citrulline and/or elevated C5-OH levels in whom confirmatory testing showed the combination of these two abnormal analytes. Mitochondrial sequencing revealed known pathogenic variants in MT-ATP6 at high heteroplasmy levels in all cases. MT-ATP6 at these heteroplasmy levels is associated with Leigh syndrome, a progressive neurodegenerative disease. Patients were treated with supplemental citrulline and, in some cases, mitochondrial cofactor therapy. These six patients have not experienced metabolic crises or developmental regression, and early diagnosis and management may help prevent the neurological sequelae of Leigh syndrome. The affected mothers and siblings are asymptomatic or paucisymptomatic (e.g. intellectual disability, depression, migraines, obsessive-compulsive disorder, and poor balance) despite high heteroplasmy or apparent homoplasmy of the familial variant, thus expanding the clinical spectrum seen in pathogenic variants of MT-ATP6. Confirmatory plasma amino acid analysis and acylcarnitine profiling should be ordered in a patient with either low citrulline and/or elevated C5-OH, as this combination appears specific for pathogenic variants in MT-ATP6.

| S-EPMC8578202 | biostudies-literature

Genetic dysfunction of MT-ATP6 causes axonal Charcot-Marie-Tooth disease.

Project description:ObjectiveCharcot-Marie-Tooth (CMT) disease is the most common inherited neuromuscular disorder, affecting 1 in 2,500 individuals. Mitochondrial DNA (mtDNA) mutations are not generally considered within the differential diagnosis of patients with uncomplicated inherited neuropathy, despite the essential requirement of ATP for axonal function. We identified the mtDNA mutation m.9185T>C in MT-ATP6, encoding the ATP6 subunit of the mitochondrial ATP synthase (OXPHOS complex V), at homoplasmic levels in a family with mitochondrial disease in whom a severe motor axonal neuropathy was a striking feature. This led us to hypothesize that mutations in the 2 mtDNA complex V subunit encoding genes, MT-ATP6 and MT-ATP8, might be an unrecognized cause of isolated axonal CMT and distal hereditary motor neuropathy (dHMN).MethodsA total of 442 probands with CMT type 2 (CMT2) (270) and dHMN (172) were screened for MT-ATP6/8 mutations after exclusion of mutations in known CMT2/dHMN genes. Mutation load was quantified using restriction endonuclease analysis. Blue-native gel electrophoresis (BN-PAGE) was performed to analyze the effects of m.9185T>C on complex V structure and function.ResultsThree further probands with CMT2 harbored the m.9185T>C mutation. Some relatives had been classified as having dHMN. Patients could be separated into 4 groups according to their mutant m.9185T>C levels. BN-PAGE demonstrated both impaired assembly and reduced activity of the complex V holoenzyme.ConclusionsWe have shown that m.9185T>C in MT-ATP6 causes CMT2 in 1.1% of genetically undefined cases. This has important implications for diagnosis and genetic counseling. Recognition that mutations in MT-ATP6 cause CMT2 enhances current understanding of the pathogenic basis of axonal neuropathy.

| S-EPMC3525307 | biostudies-literature

Alterations of plasma cytokine biomarkers for identifying age at onset of schizophrenia with neurological soft signs.

Project description:Several studies have been suggested that immunity plays a part in neurodevelopment and schizophrenia pathogenesis. Early age of onset in schizophrenia is associated with genetic factors which affect neurodevelopment. This study aims to identify immune abnormalities associated with neurodevelopmental impairments in early-onset schizophrenia (EOS) and adult-onset schizophrenia (AOS) patients. We determined the plasma levels of six cytokines (IL-1β, IL-4, IL-6, IL-10, IL-12 and TNF-α) in schizophrenia patients and healthy controls. Measurements included neurological soft signs (NSS) to distinguish and subgroup those with neurodevelopmental impairments. The study included 210 schizophrenia patients, which were divided into 84 EOS and 126 AOS patients, as well as 122 healthy controls. We observed significant differences in levels of IL-4, IL-6 and IL-10 between EOS and AOS patients. The results demonstrated the area under ROC curve (AUC) of the IL-4 in EOS and healthy controls was 0.81. Moreover, these results indicated that AUC of the IL-4 and the combination of IL-4, IL-6 and IL-12 in EOS with NSS and healthy controls were 0.91 and 0.95. These cytokines are altered in EOS and schizophrenia patients with neurodevelopmental impairments and demonstrated good classification abilities. These findings manifested that both pro- and anti-inflammatory cytokines are contributed to the clinical and pathophysiological features of schizophrenia. Future works are expected to explore potential genetic effectors and predictors as well as therapeutic directions in personalized medicine for early-onset schizophrenia.

| S-EPMC6990880 | biostudies-literature