RESUMEN
We report a neonatal patient with hypertrophic cardiomyopathy (HCM), lactic acidosis and isolated complex I deficiency. Using a customized next-generation sequencing panel, we identified a novel hemizygous variant c.338G>A in the X-linked NDUFB11 gene that encodes the NADH: ubiquinone oxidoreductase subunit B11 of the mitochondrial respiratory chain (MRC) complex I (CI). Molecular and functional assays performed in the proband's target tissuesskeletal and heart muscleshowed biochemical disturbances of the MRC, suggesting a pathogenic role for this variant. In silico analyses initially predicted an amino acid missense change p.(Arg113Lys) in the NDUFB11 CI subunit. However, we showed that the molecular effect of the c.338G>A variant, which is located at the last nucleotide of exon 2 of the NDUFB11 gene in the canonical 'short' transcript (sized 462 bp), instead causes a splicing defect triggering the up-regulation of the expression of an alternative 'long' transcript (sized 492 bp) that can also be detected in the control individuals. Our results support the hypothesis that the canonical 'short' transcript is required for the proper NDUFB11 protein synthesis, which is essential for optimal CI assembly and activity, whereas the longer alternative transcript seems to represent a non-functional, unprocessed splicing intermediate. Our results highlight the importance of characterizing the molecular effect of new variants in the affected patient's tissues to demonstrate their pathogenicity and association with the clinical phenotypes.
Asunto(s)
Cardiomiopatías , Cardiomiopatía Hipertrófica , Enfermedades Mitocondriales , Humanos , Cardiomiopatías/genética , Enfermedades Mitocondriales/genética , Complejo I de Transporte de Electrón/genética , Cardiomiopatía Hipertrófica/genética , Cardiomiopatía Hipertrófica/patología , Mutación , LinajeRESUMEN
BACKGROUND: Mitochondrial progressive external ophthalmoplegia (PEO) encompasses a broad spectrum of clinical and genetic disorders. We describe the phenotypic subtypes of PEO and its correlation with molecular defects and propose a diagnostic algorithm. METHODS: Retrospective analysis of the clinical, pathological and genetic features of 89 cases. RESULTS: Three main phenotypes were found: 'pure PEO' (42%), consisting of isolated palpebral ptosis with ophthalmoparesis; Kearns-Sayre syndrome (10%); and 'PEO plus', which associates extraocular symptoms, distinguishing the following subtypes: : myopathic (33%), bulbar (12%) and others (3%). Muscle biopsy was the most accurate test, showing mitochondrial changes in 95%. Genetic diagnosis was achieved in 96% of the patients. Single large-scale mitochondrial DNA (mtDNA) deletion was the most frequent finding (63%), followed by multiple mtDNA deletions (26%) due to mutations in TWNK (n=8), POLG (n=7), TK2 (n=6) or RRM2B (n=2) genes, and point mtDNA mutations (7%). Three new likely pathogenic mutations were identified in the TWNK and MT-TN genes. CONCLUSIONS: Phenotype-genotype correlations cannot be brought in mitochondrial PEO. Muscle biopsy should be the first step in the diagnostic flow of PEO when mitochondrial aetiology is suspected since it also enables the study of mtDNA rearrangements. If no mtDNA deletions are identified, whole mtDNA sequencing should be performed.
Asunto(s)
Proteínas de Ciclo Celular/genética , ADN Helicasas/genética , ADN Polimerasa gamma/genética , Mitocondrias/genética , Proteínas Mitocondriales/genética , Oftalmoplejía Externa Progresiva Crónica/genética , Ribonucleótido Reductasas/genética , Adolescente , Biopsia , Niño , Preescolar , ADN Mitocondrial/genética , Femenino , Humanos , Lactante , Recién Nacido , Síndrome de Kearns-Sayre/genética , Síndrome de Kearns-Sayre/patología , Masculino , Mitocondrias/patología , Enfermedades Mitocondriales/genética , Enfermedades Mitocondriales/patología , Músculo Esquelético/metabolismo , Músculo Esquelético/patología , Oftalmoplejía Externa Progresiva Crónica/patología , Fenotipo , Mutación Puntual/genética , Timidina QuinasaRESUMEN
Our goal was to analyze postmortem tissues of an adult patient with late-onset thymidine kinase 2 (TK2) deficiency who died of respiratory failure. Compared with control tissues, we found a low mtDNA content in the patient's skeletal muscle, liver, kidney, small intestine, and particularly in the diaphragm, whereas heart and brain tissue showed normal mtDNA levels. mtDNA deletions were present in skeletal muscle and diaphragm. All tissues showed a low content of OXPHOS subunits, and this was especially evident in diaphragm, which also exhibited an abnormal protein profile, expression of non-muscular ß-actin and loss of GAPDH and α-actin. MALDI-TOF/TOF mass spectrometry analysis demonstrated the loss of the enzyme fructose-bisphosphate aldolase, and enrichment for serum albumin in the patient's diaphragm tissue. The TK2-deficient patient's diaphragm showed a more profound loss of OXPHOS proteins, with lower levels of catalase, peroxiredoxin 6, cytosolic superoxide dismutase, p62 and the catalytic subunits of proteasome than diaphragms of ventilated controls. Strong overexpression of TK1 was observed in all tissues of the patient with diaphragm showing the highest levels. TK2 deficiency induces a more profound dysfunction of the diaphragm than of other tissues, which manifests as loss of OXPHOS and glycolytic proteins, sarcomeric components, antioxidants and overactivation of the TK1 salvage pathway that is not attributed to mechanical ventilation.
Asunto(s)
ADN Mitocondrial/genética , ADN Mitocondrial/metabolismo , Diafragma/metabolismo , Mitocondrias/metabolismo , Insuficiencia Respiratoria/metabolismo , Timidina Quinasa/deficiencia , Timidina Quinasa/genética , Actinas/metabolismo , Adulto , Autopsia , Encéfalo/metabolismo , Catalasa/metabolismo , Diafragma/enzimología , Femenino , Fructosa-Bifosfato Aldolasa/metabolismo , Gliceraldehído-3-Fosfato Deshidrogenasa (Fosforilante)/metabolismo , Humanos , Intestino Delgado/metabolismo , Riñón/metabolismo , Hígado/metabolismo , Espectrometría de Masas , Mitocondrias/enzimología , Mitocondrias/genética , Músculo Esquelético/metabolismo , Fosforilación Oxidativa , Peroxiredoxina VI/metabolismo , Complejo de la Endopetidasa Proteasomal , Proteoma/genética , Proteoma/metabolismo , Insuficiencia Respiratoria/genética , Insuficiencia Respiratoria/mortalidad , Superóxido Dismutasa/metabolismo , Timidina Quinasa/metabolismo , Regulación hacia ArribaRESUMEN
Uniparental disomy (UPD) is an underestimated cause of autosomal recessive disorders. In this study, we aim to raise awareness about the possibility of UPD in mitochondrial disorders - where it is a hardly described event -, by functionally characterizing a novel variant in a structural subunit of complex I (CI) of the mitochondrial oxidative phosphorylation system. Using next-generation sequencing, we identified a new intronic homozygous c.350â¯+â¯5Gâ¯>â¯A variant in the NDUFS4 gene in a one-year-old girl (being alive at the age of 7) belonging to a non-consanguineous family presenting with encephalopathy, psychomotor delay, lactic acidosis and a single CI deficiency, a less severe phenotype than those previously reported in most NDUFS4 patients. One parent lacked the variant, and microsatellite genotyping showed complete paternal uniparental isodisomy of the non-imprinted chromosome 5. We demonstrated in patient's skeletal muscle and fibroblasts splicing abnormalities, low expression of NDUFS4, undetectable NDUFS4 protein, defects in cellular respiration (decreased oxygen consumption and ATP production), and impaired assembly or stability of mitochondrial supercomplexes containing CI. Our findings support that c.350â¯+â¯5Gâ¯>â¯A variant is pathogenic, and reinforce that UPD, although rare, should be considered as a possible cause of mitochondrial diseases in order to provide accurate genetic counselling.
Asunto(s)
Complejo I de Transporte de Electrón/deficiencia , Complejo I de Transporte de Electrón/genética , Enfermedades Mitocondriales/genética , Disomía Uniparental/genética , Complejo I de Transporte de Electrón/metabolismo , Femenino , Predisposición Genética a la Enfermedad , Homocigoto , Humanos , Lactante , Enfermedades Mitocondriales/metabolismo , Enfermedades Mitocondriales/patología , Mutación/genética , Empalme del ARN/genética , Disomía Uniparental/patologíaRESUMEN
Lethal neonatal encephalopathies are heterogeneous congenital disorders that can be caused by mitochondrial dysfunction. Biallelic large deletions in the contiguous ATAD3B and ATAD3A genes, encoding mitochondrial inner membrane ATPases of unknown function, as well as compound heterozygous nonsense and missense mutations in the ATAD3A gene have been recently associated with fatal neonatal cerebellar hypoplasia. In this work, whole exome sequencing (WES) identified the novel homozygous variant c.1217â¯Tâ¯>â¯G in ATAD3A, predicting a p.(Leu406Arg) substitution, in four siblings from a consanguineous family presenting with fatal neonatal cerebellar hypoplasia, seizures, axial hypotonia, hypertrophic cardiomyopathy, hepatomegaly, congenital cataract, and dysmorphic facies. Biochemical phenotypes of the patients included hyperlactatemia and hypocholesterolemia. Healthy siblings and parents were heterozygous for this variant, which is predicted to introduce a polar chain within the catalytic domain of ATAD3A that shortens its beta-sheet structure, presumably affecting protein stability. Accordingly, patient's fibroblasts with the homozygous variant displayed a specific reduction in ATAD3A protein levels associated with profound ultrastructural alterations of mitochondrial cristae and morphology. Our findings exclude the causative role of ATAD3B on this severe phenotype, expand the phenotypical spectrum of ATAD3A pathogenic variants and emphasize the vital role of ATAD3A in mitochondrial biogenesis.
Asunto(s)
ATPasas Asociadas con Actividades Celulares Diversas/genética , Cerebelo/anomalías , Genes Recesivos , Predisposición Genética a la Enfermedad , Proteínas de la Membrana/genética , Proteínas Mitocondriales/genética , Mutación , Malformaciones del Sistema Nervioso/genética , Malformaciones del Sistema Nervioso/patología , ATPasas Asociadas con Actividades Celulares Diversas/química , Alelos , Sustitución de Aminoácidos , Cerebelo/diagnóstico por imagen , Cerebelo/patología , Niño , Preescolar , Discapacidades del Desarrollo/diagnóstico por imagen , Discapacidades del Desarrollo/genética , Discapacidades del Desarrollo/patología , Femenino , Estudios de Asociación Genética , Genotipo , Humanos , Lactante , Masculino , Proteínas de la Membrana/química , Mitocondrias/genética , Mitocondrias/metabolismo , Mitocondrias/ultraestructura , Proteínas Mitocondriales/química , Modelos Moleculares , Malformaciones del Sistema Nervioso/diagnóstico por imagen , Linaje , Conformación Proteica , Relación Estructura-Actividad , Ultrasonografía/métodos , Secuenciación del ExomaRESUMEN
Patients with acute ischemic stroke (AIS) suffer from infections associated with mortality. The relevance of the innate immune system, and monocytes in particular, has emerged as an important factor in the evolution of these infections. The study enrolled 14 patients with AIS, without previous treatment, and 10 healthy controls. In the present study, we show that monocytes from patients with AIS exhibit a refractory state or endotoxin tolerance. The patients were unable to orchestrate an inflammatory response against LPS and expressed three factors reported to control the evolution of human monocytes into a refractory state: IL-1R-associated kinase-M, NFkB2/p100, and hypoxia-inducible factor-1α. The levels of circulating mitochondrial DNA (mtDNA) in patients with AIS correlated with impaired inflammatory response of isolated monocytes. Interestingly, the patients could be classified into two groups: those who were infected and those who were not, according to circulating mtDNA levels. This finding was validated in an independent cohort of 23 patients with AIS. Additionally, monocytes from healthy controls, cultured in the presence of both sera from patients and mtDNA, reproduced a refractory state after endotoxin challenge. This effect was negated by either a TLR9 antagonist or DNase treatment. The present data further extend our understanding of endotoxin tolerance implications in AIS. A putative role of mtDNA as a new biomarker of stroke-associated infections, and thus a clinical target for preventing poststroke infection, has also been identified.
Asunto(s)
Biomarcadores/sangre , Células Sanguíneas/inmunología , ADN Mitocondrial/sangre , Infecciones/inmunología , Isquemia/inmunología , Monocitos/inmunología , Accidente Cerebrovascular/inmunología , Enfermedad Aguda , Anciano , Anciano de 80 o más Años , Células Cultivadas , Endotoxinas/inmunología , Femenino , Humanos , Tolerancia Inmunológica , Inmunidad Innata , Infecciones/etiología , Isquemia/complicaciones , Masculino , Persona de Mediana Edad , Accidente Cerebrovascular/complicacionesRESUMEN
PURPOSE: McArdle disease is a metabolic disorder caused by pathogenic mutations in the PYGM gene. Timely diagnosis can sometimes be difficult with direct genomic analysis, which requires additional studies of cDNA from muscle transcripts. Although the "nonsense-mediated mRNA decay" (NMD) eliminates tissue-specific aberrant transcripts, there is some residual transcription of tissue-specific genes in virtually all cells, such as peripheral blood mononuclear cells (PBMCs). METHODS: We studied a subset of the main types of PYGM mutations (deletions, missense, nonsense, silent, or splicing mutations) in cDNA from easily accessible cells (PBMCs) in 12 McArdle patients. RESULTS: Analysis of cDNA from PBMCs allowed detection of all mutations. Importantly, the effects of mutations with unknown pathogenicity (silent and splicing mutations) were characterized in PBMCs. Because the NMD mechanism does not seem to operate in nonspecific cells, PBMCs were more suitable than muscle biopsies for detecting the pathogenicity of some PYGM mutations, notably the silent mutation c.645G>A (p.K215=), whose effect in the splicing of intron 6 was unnoticed in previous muscle transcriptomic studies. CONCLUSION: We propose considering the use of PBMCs for detecting mutations that are thought to cause McArdle disease, particularly for studying their actual pathogenicity.Genet Med 18 11, 1128-1135.
Asunto(s)
Glucógeno Fosforilasa de Forma Muscular/sangre , Enfermedad del Almacenamiento de Glucógeno Tipo V/sangre , Enfermedad del Almacenamiento de Glucógeno Tipo V/genética , Patología Molecular/métodos , Adolescente , Adulto , Codón sin Sentido/genética , Femenino , Glucógeno Fosforilasa de Forma Muscular/genética , Enfermedad del Almacenamiento de Glucógeno Tipo V/patología , Humanos , Leucocitos Mononucleares , Masculino , Persona de Mediana Edad , Empalme del ARN/genética , Eliminación de Secuencia/genética , Adulto JovenRESUMEN
Oxidative phosphorylation system (OXPHOS) deficiencies are rare diseases but constitute the most frequent inborn errors of metabolism. We analyzed the autophagy route in 11 skin fibroblast cultures derived from patients with well characterized and distinct OXPHOS defects. Mitochondrial membrane potential determination revealed a tendency to decrease in 5 patients' cells but reached statistical significance only in 2 of them. The remaining cells showed either no change or a slight increase in this parameter. Colocalization analysis of mitochondria and autophagosomes failed to show evidence of increased selective elimination of mitochondria but revealed more intense autophagosome staining in patients' fibroblasts compared with controls. Despite the absence of increased mitophagy, Parkin recruitment to mitochondria was detected in both controls' and patients' cells and was slightly higher in cells harboring complex I defects. Western blot analysis of the autophagosome marker LC3B, confirmed significantly higher levels of the protein bound to autophagosomes, LC3B-II, in patients' cells, suggesting an increased bulk autophagy in OXPHOS defective fibroblasts. Inhibition of lysosomal proteases caused significant accumulation of LC3B-II in control cells, whereas in patients' cells this phenomenon was less pronounced. Electron microscopy studies showed higher content of late autophagic vacuoles and lysosomes in OXPHOS defective cells, accompanied by higher levels of the lysosomal marker LAMP-1. Our findings suggest that in OXPHOS deficient fibroblasts autophagic flux could be partially hampered leading to an accumulation of autophagic vacuoles and lysosomes.
Asunto(s)
Autofagia/fisiología , Mitocondrias/fisiología , Enfermedades Mitocondriales/patología , Mitofagia/fisiología , Adenosina Trifosfato/metabolismo , Células Cultivadas , Fibroblastos/metabolismo , Fibroblastos/fisiología , Humanos , Proteínas de Membrana de los Lisosomas/metabolismo , Lisosomas/metabolismo , Lisosomas/fisiología , Potencial de la Membrana Mitocondrial/fisiología , Proteínas Asociadas a Microtúbulos/metabolismo , Mitocondrias/metabolismo , Enfermedades Mitocondriales/metabolismo , Enfermedades Mitocondriales/fisiopatología , Fagosomas/metabolismo , Fagosomas/fisiologíaRESUMEN
OBJECTIVES: Thymidine kinase 2 deficiency (TK2d) is a rare autosomal recessive mitochondrial disorder. It manifests as a continuous clinical spectrum, from fatal infantile mitochondrial DNA depletion syndromes to adult-onset mitochondrial myopathies characterized by ophthalmoplegia-plus phenotypes with early respiratory involvement. Treatment with pyrimidine nucleosides has recently shown striking effects on survival and motor outcomes in the more severe infantile-onset clinical forms. We present the response to treatment in a patient with adult-onset TK2d. METHODS: An adult with ptosis, ophthalmoplegia, facial, neck, and proximal muscle weakness, non-invasive nocturnal mechanical ventilation, and dysphagia due to biallelic pathogenic variants in TK2 received treatment with 260 mg/kg/day of deoxycytidine (dC) and deoxythymidine (dT) under a Compassionate Use Program. Prospective motor and respiratory assessments are presented. RESULTS: After 27 months of follow-up, the North Star Ambulatory Assessment improved by 11 points, he walked 195 m more in the 6 Minute-Walking-Test, ran 10 s faster in the 100-meter time velocity test, and the Forced Vital Capacity stabilized. Growth Differentiation Factor-15 (GDF15) levels, a biomarker of respiratory chain dysfunction, normalized. The only reported side effect was dose-dependent diarrhea. DISCUSSION: Treatment with dC and dT can significantly improve motor performance and stabilize respiratory function safely in patients with adult-onset TK2d.
Asunto(s)
Timidina Quinasa , Humanos , Masculino , Timidina Quinasa/genética , Timidina Quinasa/deficiencia , Administración Oral , Adulto , Resultado del Tratamiento , Enfermedades Mitocondriales/tratamiento farmacológico , Enfermedades Mitocondriales/genética , Nucleósidos/uso terapéutico , Nucleósidos/administración & dosificaciónRESUMEN
Objectives: Thymidine kinase 2 deficiency (TK2d) is a rare autosomal recessive disorder that stems from a perturbation of the mitochondrial DNA maintenance. Nucleoside treatment has recently shown promise as a disease-modifying therapy. TK2d was initially associated with rapidly progressive fatal myopathy in children featuring mitochondrial DNA depletion. Subsequently, less severe variants of the disease were described, with onset of symptoms during adolescence or adulthood and associated with the presence of multiple mtDNA deletions. These less severe phenotypes have been reported in only 15% of the approximately 120 patients described worldwide. However, some reports suggest that these juvenile and adult-onset presentations may be more common. The objective of this study was to describe the clinical phenotype in a sample of patients from Spain. Methods: This study includes 53 patients harboring biallelic TK2 pathogenic variants, compiling data retrospectively from 7 Spanish centers. We analyzed allele frequency, investigated the most recent common ancestor of core haplotypes, and used the Runs of Homozygosity approach to investigate variant coalescence. Results: Symptom onset distribution revealed that 32 patients (60%) experienced symptoms beyond 12 years of age. Approximately 30% of patients died of respiratory insufficiency, while 56% of surviving patients needed mechanical ventilation. Genetic analysis identified 16 distinct variants in TK2. Two variants, p.Lys202del and p.Thr108Met, exhibited significantly higher prevalence in the Spanish population than that reported in gnomAD database (86-fold and 13-fold, respectively). These variants are estimated to have originated approximately 16.8 generations ago for p.Thr108Met and 95.2 generations ago for p.Lys202del within the Spanish population, with the increase in frequency attributed to various forms of inbreeding. In late-onset cases, 46.9% carried the p.Lys202del variant. Discussion: The higher frequency of TK2d in Spain can be partially attributed to the increased prevalence of 2 variants and consanguinity. Notably, in 60% of the cohort, the disease was late-onset, emphasizing the potential underdiagnosis of this subgroup of patients in other regions. Raising awareness of this potentially treatable disorder is of utmost importance because early interventions can significantly affect the quality of life and survival of affected individuals.
RESUMEN
BACKGROUND: Mitochondrial disorders (MD) are multisystem diseases that arise as a result of dysfunction of the oxidative phosphorylation system. The predominance of neuromuscular manifestations in MD could mask the presence of other clinical phenotypes such as cardiac dysfunction. Reported here is a retrospective study, the main objective of which was to characterize the clinical and molecular features of a cohort of patients with cardiomyopathy and MD. METHODS AND RESULTS: Hospital charts of 2,520 patients, evaluated for presumed MD were reviewed. The clinical criterion for inclusion in this study was the presence of a cardiac disturbance accompanied by a mitochondrial dysfunction. Only 71 patients met this criterion. The mitochondrial genome (mtDNA) could be sequenced only in 45 and the pathogenicity of 2 of the found changes was investigated using transmitochondrial cybrids. Three nucleotide changes in mtDNA that may be relevant and 3 with confirmed pathogenicity were identified but no mutations were found in the 13 nuclear genes analyzed. CONCLUSIONS: The mtDNA should be sequenced in patients with cardiac dysfunction accompanied by symptoms suggestive of MD; databases should be carefully and periodically screened to discard mitochondrial variants that could be associated with MD; functional assays are necessary to classify mitochondrial variants as pathogenic or polymorphic; and additional efforts must be made in order to identify nuclear genes that can explain some as yet uncharacterized molecular features of mitochondrial cardiomyopathy.
Asunto(s)
Cardiomiopatías , Genoma Mitocondrial , Enfermedades Mitocondriales , Polimorfismo Genético , Adolescente , Adulto , Cardiomiopatías/complicaciones , Cardiomiopatías/genética , Cardiomiopatías/metabolismo , Cardiomiopatías/patología , Niño , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Enfermedades Mitocondriales/complicaciones , Enfermedades Mitocondriales/genética , Enfermedades Mitocondriales/metabolismo , Enfermedades Mitocondriales/patología , Estudios RetrospectivosRESUMEN
Primary mitochondrial myopathies (PMM) are a clinically and genetically highly heterogeneous group that, in some cases, may manifest exclusively as fatigue and exercise intolerance, with minimal or no signs on examination. On these occasions, the symptoms can be confused with the much more common chronic fatigue syndrome (CFS). Nonetheless, other possibilities must be excluded for the final diagnosis of CFS, with PMM being one of the primary differential diagnoses. For this reason, many patients with CFS undergo extensive studies, including extensive genetic testing and muscle biopsies, to rule out this possibility. This study evaluated the diagnostic performance of growth differentiation factor-15 (GDF-15) as a potential biomarker to distinguish which patient with chronic fatigue has a mitochondrial disorder. We studied 34 adult patients with symptoms of fatigue and exercise intolerance with a definitive diagnosis of PMM (7), CFS (22), or other non-mitochondrial disorders (5). The results indicate that GDF-15 can accurately discriminate between patients with PMM and CFS (AUC = 0.95) and between PMM and patients with fatigue due to other non-mitochondrial disorders (AUC = 0.94). Therefore, GDF-15 emerges as a promising biomarker to select which patients with fatigue should undergo further studies to exclude mitochondrial disease.
RESUMEN
Spike anchors are one of the most promising techniques to prevent or delay debonding in FRP reinforcement sheets. There are several parameters affecting the anchors' capacity, such as the embedment length and dowel angle. Regardless of the anchors' capacity, their contribution to the overall strength of the anchored joint is affected by a larger number of variables, including the bonded length behind the anchors, the number and arrangement of the anchors, and the contact surface between the anchor fan and the FRP sheet. This paper presents experimental results of 10 tests conducted on concrete beams. In the tests, anchored joints reached peak loads up to 155% of those of unanchored, bonded joints. The main finding of the research is that the bond length in front of and behind the anchors affects both the peak load and the overall behaviour, with unbonded anchored joints exhibiting a poor behaviour and premature slippage of the anchor, without achieving its failure due to fibre rupture.
RESUMEN
Lactate dehydrogenase (LDH) catalyzes the reversible conversion of L-lactate to pyruvate. LDH-A deficiency is an autosomal recessive disorder (glycogenosis type XI, OMIM#612933) caused by mutations in the LDHA gene. We present two young adult female patients presenting with intolerance to anaerobic exercise, episodes of rhabdomyolysis, and, in one of the patients, psoriasis-like dermatitis. We identified in the LDHA gene a homozygous c.410C>A substitution that predicts a p.Ser137Ter nonsense mutation in Patient One and a compound heterozygous c.410C>A (p.Ser137Ter) and c.750G>A (p.Trp250Ter) nonsense mutation in Patient Two. The pathogenicity of the variants was demonstrated by electrophoretic separation of LDH isoenzymes. Moreover, a flat lactate curve on the forearm exercise test, along with the clinical combination of myopathy and psoriatic-like dermatitis, can also lead to the diagnosis.
Asunto(s)
Dermatitis , Enfermedad del Almacenamiento de Glucógeno , Humanos , Femenino , Lactato Deshidrogenasa 5 , Isoenzimas/genética , Isoenzimas/metabolismo , Codón sin Sentido , Ácido Láctico/metabolismo , Ácido Pirúvico , MutaciónRESUMEN
The health effects of (poly)phenols (PPs) depend upon their bioavailability that, in general, is very low and shows a high interindividual variability. The low bioavailability of PPs is mainly attributed to their low absorption in the upper gastrointestinal tract as a result of their low water solubility, their presence in foods as polymers or in glycosylated forms, and their tight bond to food matrices. Although many studies have investigated how technological and biotechnological processes affect the phenolic composition of fruits and vegetables, limited information exists regarding their effects on PP bioavailability in humans. In the present review, the effect of food processing (mechanical, thermal, and non-thermal treatments), oral-delivery nanoformulations, enzymatic hydrolysis, fermentation, co-administration with probiotics, and generation of postbiotics in PP bioavailability have been overviewed, focusing in the evidence provided in humans.
Asunto(s)
Dieta , Fenoles , Disponibilidad Biológica , Frutas/química , Humanos , Fenoles/química , Polifenoles/análisis , VerdurasRESUMEN
This historical cohort study evaluated clinical characteristics of progression and prognosis in adults with thymidine kinase 2 deficiency (TK2d). Records were available for 17 untreated adults with TK2d (mean age of onset, 32 years), including longitudinal data from 6 patients (mean follow-up duration, 26.5 months). Pearson's correlation assessed associations between standard motor and respiratory assessments, clinical characteristics, and laboratory values. Longitudinal data were assessed by linear regression mixed models. Respiratory involvement progressed at an annual rate of 8.16% decrement in forced vital capacity (FVC). Most patients under noninvasive ventilation (NIV) remained ambulant (12/14, 86%), reduced FVC was not associated with concomitant decline in 6-minute walk test (6MWT), and 6MWT results were not correlated with FVC. Disease severity, assessed by age at NIV onset, correlated most strongly at diagnosis with: creatinine levels (râ¯=â¯0.8036; Pâ¯=â¯0.0009), followed by FVC (râ¯=â¯0.7265; Pâ¯=â¯0.0033), mtDNA levels in muscle (râ¯=â¯0.7933; Pâ¯=â¯0.0188), and age at disease onset (râ¯=â¯0.7128; Pâ¯=â¯0.0042). This population of adults with TK2d demonstrates rapid deterioration of respiratory muscles, which progresses independently of motor impairment. The results support FVC at diagnosis, mtDNA levels in muscle, and age at disease onset as prognostic indicators. Creatinine levels may also be potentially prognostic, as previously reported in other neuromuscular disorders.
Asunto(s)
ADN Mitocondrial , Adulto , Estudios de Cohortes , Creatinina , Humanos , Pronóstico , Timidina Quinasa , Capacidad Vital/fisiologíaRESUMEN
The quantification of mitochondrial respiratory chain (MRC) enzymatic activities is essential for diagnosis of a wide range of mitochondrial diseases, ranging from inherited defects to secondary dysfunctions. MRC lesion is frequently linked to extended cell damage through the generation of proton leak or oxidative stress, threatening organ viability and patient health. However, the intrinsic challenge of a methodological setup and the high variability in measuring MRC enzymatic activities represents a major obstacle for comparative analysis amongst institutions. To improve experimental and statistical robustness, seven Spanish centers with extensive experience in mitochondrial research and diagnosis joined to standardize common protocols for spectrophotometric MRC enzymatic measurements using minimum amounts of sample. Herein, we present the detailed protocols, reference ranges, tips and troubleshooting methods for experimental and analytical setups in different sample preparations and tissues that will allow an international standardization of common protocols for the diagnosis of MRC defects. Methodological standardization is a crucial step to obtain comparable reference ranges and international standards for laboratory assays to set the path for further diagnosis and research in the field of mitochondrial diseases.
RESUMEN
OBJECTIVES: We aimed to determine whether the plasma profile of lactate dehydrogenase (LDH) isoenzymes is altered in patients with COVID-19, and whether this is attributable to a specific release of LDH-3, the main LDH isoenzyme expressed in lungs. DESIGN: We collected fresh plasma aliquots from 17 patients (LDH range, 281-822 U/L) and seven controls (LDH â< â230 U/L). In-gel relative activity of the different LDH isoenzymes was determined by electrophoresis and densitometric analysis. RESULTS: Despite the expected higher total LDH activity levels in patients (p â< â0.001), the in-gel relative activities of LDH isoenzymes did not differ between patients and controls (all p â> â0.05). We found no correlation between total plasma LDH activity and the in-gel relative activities of the different LDH isoenzymes, including LDH-3. Likewise, there was no correlation between LDH-3 and various routine haematological and serum parameters that have been previously reported to be altered in COVID-19 (such as lymphocyte count, albumin, alanine and aspartate aminotransferase, creatinine, C-reactive protein, or ferritin). CONCLUSIONS: Our findings suggest that elevation of plasma LDH activity in patients with COVID-19 is not associated to a specific release of LDH-3 into the bloodstream, and do not support the use of LDH as a specific biomarker for lung affectation in patients with COVID-19.
RESUMEN
Mutations in BCS1L, an assembly factor that facilitates the insertion of the catalytic Rieske Iron-Sulfur subunit into respiratory chain complex III, result in a wide variety of clinical phenotypes that range from the relatively mild Björnstad syndrome to the severe GRACILE syndrome. To better understand the pathophysiological consequences of such mutations, we studied fibroblasts from six complex III-deficient patients harboring mutations in the BCS1L gene. Cells from patients with the most severe clinical phenotypes exhibited slow growth rates in glucose medium, variable combined enzyme deficiencies, and assembly defects of respiratory chain complexes I, III, and IV, increased H(2)O(2) levels, unbalanced expression of the cellular antioxidant defenses, and apoptotic cell death. In addition, all patients showed cytosolic accumulation of the BCS1L protein, suggestive of an impaired mitochondrial import, assembly or stability defects of the BCS1L complex, fragmentation of the mitochondrial networks, and decreased MFN2 protein levels. The observed structural alterations were independent of the respiratory chain function and ROS production. Our results provide new insights into the role of pathogenic BCS1L mutations in mitochondrial function and dynamics.
Asunto(s)
Complejo III de Transporte de Electrones/deficiencia , Complejo III de Transporte de Electrones/genética , Fibroblastos/patología , Mitocondrias/enzimología , Mitocondrias/patología , Mutación/genética , ATPasas Asociadas con Actividades Celulares Diversas , Antioxidantes/metabolismo , Apoptosis , Western Blotting , Proliferación Celular , Células Cultivadas , Preescolar , ADN Complementario/genética , Resultado Fatal , Femenino , Fibroblastos/enzimología , Humanos , Lactante , Recién Nacido , Masculino , Especies Reactivas de Oxígeno/metabolismo , Piel/patología , Fracciones Subcelulares/metabolismoRESUMEN
Leigh syndrome (LS) usually presents as an early onset mitochondrial encephalopathy characterized by bilateral symmetric lesions in the basal ganglia and cerebral stem. More than 75 genes have been associated with this condition, including genes involved in the biogenesis of mitochondrial complex I (CI). In this study, we used a next-generation sequencing (NGS) panel to identify two novel biallelic variants in the NADH:ubiquinone oxidoreductase subunit A13 (NDUFA13) gene in a patient with isolated CI deficiency in skeletal muscle. Our patient, who represents the second family report with mutations in the CI NDUFA13 subunit, presented with LS lesions in brain magnetic resonance imaging, mild hypertrophic cardiomyopathy, and progressive spastic tetraparesis. This phenotype manifestation is different from that previously described in the first NDUFA13 family, which was predominantly characterized by neurosensorial symptoms. Both in silico pathogenicity predictions and oxidative phosphorylation (OXPHOS) functional findings in patient's skin fibroblasts (delayed cell growth, isolated CI enzyme defect, decreased basal and maximal oxygen consumption and as well as ATP production, together with markedly diminished levels of the NDUFA13 protein, CI, and respirasomes) suggest that these novel variants in the NDUFA13 gene are the underlying cause of the CI defect, expanding the genetic heterogeneity of LS.