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OBJECTIVE: Biallelic titin truncating variants (TTNtv) have been associated with a wide phenotypic spectrum, ranging from complex prenatal muscle diseases with dysmorphic features to adult-onset limb-girdle muscular dystrophy, with or without cardiac involvement. Given the size and complexity of TTN, reaching an unequivocal molecular diagnosis and precise disease prognosis remains challenging. METHODS: In this case series, 12 unpublished cases and one already published case with biallelic TTNtv were collected from multiple international medical centers between November 2022 and September 2023. TTN mutations were detected through exome or genome sequencing. Information about familial and personal clinical history was collected in a standardized form. RNA-sequencing and analysis of TTN exon usage were performed on an internal sample cohort including postnatal skeletal muscles, fetal skeletal muscles, postnatal heart muscles, and fetal heart muscles. In addition, publicly available RNA-sequencing data was retrieved from ENCODE. RESULTS: We generated new RNA-seq data on TTN exons and identified genotype-phenotype correlations with prognostic implications for each titinopathy patient (whether worsening or improving in prenatal and postnatal life) using percentage spliced in (PSI) data for the involved exons. Interestingly, thanks to exon usage, we were also able to rule out a titinopathy diagnosis in one prenatal case. INTERPRETATION: This study demonstrates that exon usage provides valuable insights for a more exhaustive clinical interpretation of TTNtv; additionally, it may serve as a model for implementing personalized medicine in many other genetic diseases, since most genes undergo alternative splicing.
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Conectina , Exones , Humanos , Conectina/genética , Exones/genética , Femenino , Masculino , Adulto , Progresión de la Enfermedad , Mutación , Músculo Esquelético/patología , Niño , Adolescente , PreescolarRESUMEN
OBJECTIVE: FHL1-related reducing body myopathy is an ultra-rare, X-linked dominant myopathy. In this cross-sectional study, we characterize skeletal muscle ultrasound, muscle MRI, and cardiac MRI findings in FHL1-related reducing body myopathy patients. METHODS: Seventeen patients (11 male, mean age 35.4, range 12-76 years) from nine independent families with FHL1-related reducing body myopathy underwent clinical evaluation, muscle ultrasound (n = 11/17), and lower extremity muscle MRI (n = 14/17), including Dixon MRI (n = 6/17). Muscle ultrasound echogenicity was graded using a modified Heckmatt scale. T1 and STIR axial images of the lower extremity muscles were evaluated for pattern and distribution of abnormalities. Quantitative analysis of intramuscular fat fraction was performed using the Dixon MRI images. Cardiac studies included electrocardiogram (n = 15/17), echocardiogram (n = 17/17), and cardiac MRI (n = 6/17). Cardiac muscle function, T1 maps, T2-weighted black blood images, and late gadolinium enhancement patterns were analyzed. RESULTS: Muscle ultrasound showed a distinct pattern of increased echointensity in skeletal muscles with a nonuniform, multifocal, and "geographical" distribution, selectively involving the deeper fascicles of muscles such as biceps and tibialis anterior. Lower extremity muscle MRI showed relative sparing of gluteus maximus, rectus femoris, gracilis, and lateral gastrocnemius muscles and an asymmetric and multifocal, "geographical" pattern of T1 hyperintensity within affected muscles. Cardiac studies revealed mild and nonspecific abnormalities on electrocardiogram and echocardiogram with unremarkable cardiac MRI studies. INTERPRETATION: Skeletal muscle ultrasound and muscle MRI reflect the multifocal aggregate formation in muscle in FHL1-related reducing body myopathy and are practical and informative tools that can aid in diagnosis and monitoring of disease progression.
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Medios de Contraste , Enfermedades Musculares , Humanos , Masculino , Niño , Adolescente , Adulto Joven , Adulto , Persona de Mediana Edad , Anciano , Estudios Transversales , Proteínas Musculares , Gadolinio , Músculo Esquelético/diagnóstico por imagen , Enfermedades Musculares/diagnóstico por imagen , Enfermedades Musculares/genética , Péptidos y Proteínas de Señalización Intracelular , Proteínas con Dominio LIM/genéticaRESUMEN
Spinal muscular atrophy (SMA) is a severe neuromuscular disorder caused by biallelic loss or pathogenic variants in the SMN1 gene. Copy number and modifier intragenic variants in SMN2, an almost identical paralog gene of SMN1, are known to influence the amount of complete SMN proteins. Therefore, SMN2 is considered the main phenotypic modifier of SMA, although genotype−phenotype correlation is not absolute. We present eleven unrelated SMA patients with milder phenotypes carrying the c.859G>C-positive modifier variant in SMN2. All were studied by a specific NGS method to allow a deep characterization of the entire SMN region. Analysis of two homozygous cases for the variant allowed us to identify a specific haplotype, Smn2-859C.1, in association with c.859G>C. Two other cases with the c.859G>C variant in their two SMN2 copies showed a second haplotype, Smn2-859C.2, in cis with Smn2-859C.1, assembling a more complex allele. We also identified a previously unreported variant in intron 2a exclusively linked to the Smn2-859C.1 haplotype (c.154-1141G>A), further suggesting that this region has been ancestrally conserved. The deep molecular characterization of SMN2 in our cohort highlights the importance of testing c.859G>C, as well as accurately assessing the SMN2 region in SMA patients to gain insight into the complex genotype−phenotype correlations and improve prognostic outcomes.
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Atrofia Muscular Espinal , Estudios de Asociación Genética , Homocigoto , Humanos , Intrones , Atrofia Muscular Espinal/genética , Mutación , Fenotipo , Proteína 1 para la Supervivencia de la Neurona Motora/genética , Proteína 2 para la Supervivencia de la Neurona Motora/genéticaRESUMEN
BACKGROUND: LAMA2-related muscular dystrophy (LAMA2-RD) encompasses a group of recessive muscular dystrophies caused by mutations in the LAMA2 gene, which codes for the alpha-2 chain of laminin-211 (merosin). Diagnosis is straightforward in the classic congenital presentation with no ambulation and complete merosin deficiency in muscle biopsy, but is far more difficult in milder ambulant individuals with partial merosin deficiency. OBJECTIVE: To investigate the diagnostic utility of muscle imaging in LAMA2-RD using whole-body magnetic resonance imaging (WBMRI). RESULTS: 27 patients (2-62 years, 21-80% with acquisition of walking ability and 6 never ambulant) were included in an international collaborative study. All carried two pathogenic mutations, mostly private missense changes. An intronic variant (c.909 + 7A > G) was identified in all the Chilean cases. Three patients (two ambulant) showed intellectual disability, epilepsy, and brain structural abnormalities. WBMRI T1w sequences or T2 fat-saturated images (Dixon) revealed abnormal muscle fat replacement predominantly in subscapularis, lumbar paraspinals, gluteus minimus and medius, posterior thigh (adductor magnus, biceps femoris, hamstrings) and soleus. This involvement pattern was consistent for both ambulant and non-ambulant patients. The degree of replacement was predominantly correlated to the disease duration, rather than to the onset or the clinical severity. A "COL6-like sandwich sign" was observed in several muscles in ambulant adults, but different involvement of subscapularis, gluteus minimus, and medius changes allowed distinguishing LAMA2-RD from collagenopathies. The thigh muscles seem to be the best ones to assess disease progression. CONCLUSION: WBMRI in LAMA2-RD shows a homogeneous pattern of brain and muscle imaging, representing a supportive diagnostic tool.
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Imagen por Resonancia Magnética , Distrofias Musculares , Adulto , Humanos , Laminina/genética , Imagen por Resonancia Magnética/métodos , Músculo Esquelético/diagnóstico por imagen , Músculo Esquelético/patología , Distrofias Musculares/congénito , Distrofias Musculares/diagnóstico por imagen , Distrofias Musculares/genética , Imagen de Cuerpo EnteroRESUMEN
BACKGROUND: Mitochondrial diseases are difficult to diagnose and treat. Recent advances in genetic diagnostics and more effective treatment options can improve patient diagnosis and prognosis, but patients with mitochondrial disease typically experience delays in diagnosis and treatment. Here, we describe a unique collaborative practice model among physicians and scientists in Spain focused on identifying TK2 deficiency (TK2d), an ultra-rare mitochondrial DNA depletion and deletions syndrome. MAIN BODY: This collaboration spans research and clinical care, including laboratory scientists, adult and pediatric neuromuscular clinicians, geneticists, and pathologists, and has resulted in diagnosis and consolidation of care for patients with TK2d. The incidence of TK2d is not known; however, the first clinical cases of TK2d were reported in 2001, and only ~ 107 unique cases had been reported as of 2018. This unique collaboration in Spain has led to the diagnosis of more than 30 patients with genetically confirmed TK2d across different regions of the country. Research affiliate centers have led investigative treatment with nucleosides based on understanding of TK2d clinical manifestations and disease mechanisms, which resulted in successful treatment of a TK2d mouse model with nucleotide therapy in 2010. Only 1 year later, this collaboration enabled rapid adoption of treatment with pyrimidine nucleotides (and later, nucleosides) under compassionate use. Success in TK2d diagnosis and treatment in Spain is attributable to two important factors: Spain's fully public national healthcare system, and the designation in 2015 of major National Reference Centers for Neuromuscular Disorders (CSURs). CSUR networking and dissemination facilitated development of a collaborative care network for TK2d disease, wherein participants share information and protocols to request approval from the Ministry of Health to initiate nucleoside therapy. Data have recently been collected in a retrospective study conducted under a Good Clinical Practice-compliant protocol to support development of a new therapeutic approach for TK2d, a progressive disease with no approved therapies. CONCLUSIONS: The Spanish experience in diagnosis and treatment of TK2d is a model for the diagnosis and development of new treatments for very rare diseases within an existing healthcare system.
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Modelos Animales de Enfermedad , Enfermedades Raras , Timidina Quinasa/deficiencia , Animales , Humanos , Ratones , Enfermedades Raras/diagnóstico , Estudios Retrospectivos , EspañaRESUMEN
Spinal muscular atrophy (SMA) is a neuromuscular genetic disease caused by reduced survival motor neuron (SMN) protein. SMN is ubiquitous and deficient levels cause spinal cord motoneurons (MNs) degeneration and muscle atrophy. Nevertheless, the mechanism by which SMN reduction in muscle contributes to SMA disease is not fully understood. Therefore, studies evaluating atrophy mechanisms in SMA muscles will contribute to strengthening current knowledge of the pathology. Here we propose to evaluate autophagy in SMA muscle, a pathway altered in myotube atrophy. We analized autophagy proteins and mTOR in muscle biopsies, fibroblasts, and lymphoblast cell lines from SMA patients and in gastrocnemius muscles from a severe SMA mouse model. Human MNs differentiated from SMA and unaffected control iPSCs were also included in the analysis of the autophagy. Muscle biopsies, fibroblasts, and lymphoblast cell lines from SMA patients showed reduction of the autophagy marker LC3-II. In SMA mouse gastrocnemius, we observed lower levels of LC3-II, Beclin 1, and p62/SQSTM1 proteins at pre-symptomatic stage. mTOR phosphorylation at Ser2448 was decreased in SMA muscle cells. However, in mouse and human cultured SMA MNs mTOR phosphorylation and LC3-II levels were increased. These results suggest a differential regulation in SMA of the autophagy process in muscle cells and MNs. Opposite changes in autophagy proteins and mTOR phosphorylation between muscle cells and neurons were observed. These differences may reflect a specific response to SMN reduction, which could imply diverse tissue-dependent reactions to therapies that should be taken into account when treating SMA patients.
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Autofagia/fisiología , Neuronas Motoras/patología , Músculo Esquelético/patología , Atrofia Muscular Espinal/patología , Animales , Femenino , Humanos , Masculino , Ratones , Neuronas Motoras/metabolismo , Músculo Esquelético/metabolismo , Atrofia Muscular Espinal/metabolismoRESUMEN
Sarcoglycanopathies comprise four subtypes of autosomal recessive limb-girdle muscular dystrophies (LGMDR3, LGMDR4, LGMDR5 and LGMDR6) that are caused, respectively, by mutations in the SGCA, SGCB, SGCG and SGCD genes. In 2016, several clinicians involved in the diagnosis, management and care of patients with LGMDR3-6 created a European Sarcoglycanopathy Consortium. The aim of the present study was to determine the clinical and genetic spectrum of a large cohort of patients with sarcoglycanopathy in Europe. This was an observational retrospective study. A total of 33 neuromuscular centres from 13 different European countries collected data of the genetically confirmed patients with sarcoglycanopathy followed-up at their centres. Demographic, genetic and clinical data were collected for this study. Data from 439 patients from 13 different countries were collected. Forty-three patients were not included in the analysis because of insufficient clinical information available. A total of 159 patients had a confirmed diagnosis of LGMDR3, 73 of LGMDR4, 157 of LGMDR5 and seven of LGMDR6. Patients with LGMDR3 had a later onset and slower progression of the disease. Cardiac involvement was most frequent in LGMDR4. Sixty per cent of LGMDR3 patients carried one of the following mutations, either in a homozygous or heterozygous state: c.229C>T, c.739G>A or c.850C>T. Similarly, the most common mutations in LMGDR5 patients were c.525delT or c.848G>A. In LGMDR4 patients the most frequent mutation was c.341C>T. We identified onset of symptoms before 10 years of age and residual protein expression lower than 30% as independent risk factors for losing ambulation before 18 years of age, in LGMDR3, LGMDR4 and LGMDR5 patients. This study reports clinical, genetic and protein data of a large European cohort of patients with sarcoglycanopathy. Improving our knowledge about these extremely rare autosomal recessive forms of LGMD was helped by a collaborative effort of neuromuscular centres across Europe. Our study provides important data on the genotype-phenotype correlation that is relevant for the design of natural history studies and upcoming interventional trials in sarcoglycanopathies.
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Estudios de Asociación Genética , Sarcoglicanopatías/epidemiología , Sarcoglicanopatías/genética , Adolescente , Adulto , Anciano , Niño , Preescolar , Estudios de Cohortes , Europa (Continente)/epidemiología , Femenino , Estudios de Asociación Genética/métodos , Humanos , Masculino , Persona de Mediana Edad , Distrofia Muscular de Cinturas/diagnóstico , Distrofia Muscular de Cinturas/epidemiología , Distrofia Muscular de Cinturas/genética , Estudios Retrospectivos , Sarcoglicanopatías/diagnóstico , Adulto JovenRESUMEN
OBJECTIVE: Thymidine kinase 2, encoded by the nuclear gene TK2, is required for mitochondrial DNA maintenance. Autosomal recessive TK2 mutations cause depletion and multiple deletions of mtDNA that manifest predominantly as a myopathy usually beginning in childhood and progressing relentlessly. We investigated the safety and efficacy of deoxynucleoside monophosphate and deoxynucleoside therapies. METHODS: We administered deoxynucleoside monophosphates and deoxynucleoside to 16 TK2-deficient patients under a compassionate use program. RESULTS: In 5 patients with early onset and severe disease, survival and motor functions were better than historically untreated patients. In 11 childhood and adult onset patients, clinical measures stabilized or improved. Three of 8 patients who were nonambulatory at baseline gained the ability to walk on therapy; 4 of 5 patients who required enteric nutrition were able to discontinue feeding tube use; and 1 of 9 patients who required mechanical ventilation became able to breathe independently. In motor functional scales, improvements were observed in the 6-minute walk test performance in 7 of 8 subjects, Egen Klassifikation in 2 of 3, and North Star Ambulatory Assessment in all 5 tested. Baseline elevated serum growth differentiation factor 15 levels decreased with treatment in all 7 patients tested. A side effect observed in 8 of the 16 patients was dose-dependent diarrhea, which did not require withdrawal of treatment. Among 12 other TK2 patients treated with deoxynucleoside, 2 adults developed elevated liver enzymes that normalized following discontinuation of therapy. INTERPRETATION: This open-label study indicates favorable side effect profiles and clinical efficacy of deoxynucleoside monophosphate and deoxynucleoside therapies for TK2 deficiency. ANN NEUROL 2019;86:293-303.
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Ensayos de Uso Compasivo/métodos , Desoxirribonucleósidos/uso terapéutico , Enfermedades Musculares/tratamiento farmacológico , Enfermedades Musculares/enzimología , Timidina Quinasa/deficiencia , Adulto , Niño , Preescolar , Femenino , Humanos , Masculino , Prueba de Paso/métodosRESUMEN
Next generation sequencing techniques were recently used to show mutations in COL13A1 cause synaptic basal lamina-associated congenital myasthenic syndrome type 19. Animal studies showed COL13A1, a synaptic extracellular-matrix protein, is involved in the formation and maintenance of the neuromuscular synapse that appears independent of the Agrin-LRP4-MuSK-DOK7 acetylcholine receptor clustering pathway. Here, we report the phenotypic spectrum of 16 patients from 11 kinships harbouring homozygous or heteroallelic mutations in COL13A1. Clinical presentation was mostly at birth with hypotonia and breathing and feeding difficulties often requiring ventilation and artificial feeding. Respiratory crisis related to recurrent apnoeas, sometimes triggered by chest infections, were common early in life but resolved over time. The predominant pattern of muscle weakness included bilateral ptosis (non-fatigable in adulthood), myopathic facies and marked axial weakness, especially of neck flexion, while limb muscles were less involved. Other features included facial dysmorphism, skeletal abnormalities and mild learning difficulties. All patients tested had results consistent with abnormal neuromuscular transmission. Muscle biopsies were within normal limits or showed non-specific changes. Muscle MRI and serum creatine kinase levels were normal. In keeping with COL13A1 mutations affecting both synaptic structure and presynaptic function, treatment with 3,4-diaminopyridine and salbutamol resulted in motor and respiratory function improvement. In non-treated cases, disease severity and muscle strength improved gradually over time and several adults recovered normal muscle strength in the limbs. In summary, patients with COL13A1 mutations present mostly with severe early-onset myasthenic syndrome with feeding and breathing difficulties. Axial weakness is greater than limb weakness. Disease course improves gradually over time, which could be consistent with the less prominent role of COL13A1 once the neuromuscular junction is mature. This report emphasizes the role of collagens at the human muscle endplate and should facilitate the recognition of this disorder, which can benefit from pharmacological treatment.
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Colágeno Tipo XIII/genética , Proteínas Musculares/genética , Síndromes Miasténicos Congénitos/genética , Unión Neuromuscular/metabolismo , Transmisión Sináptica/genética , Adolescente , Adulto , Niño , Femenino , Homocigoto , Humanos , Masculino , Músculo Esquelético/patología , Mutación/genética , Síndromes Miasténicos Congénitos/diagnóstico , Unión Neuromuscular/genética , Sinapsis/genética , Adulto JovenRESUMEN
Mendelian diseases have shown to be an and efficient model for connecting genotypes to phenotypes and for elucidating the function of genes. Whole-exome sequencing (WES) accelerated the study of rare Mendelian diseases in families, allowing for directly pinpointing rare causal mutations in genic regions without the need for linkage analysis. However, the low diagnostic rates of 20-30% reported for multiple WES disease studies point to the need for improved variant pathogenicity classification and causal variant prioritization methods. Here, we present the exome Disease Variant Analysis (eDiVA; http://ediva.crg.eu), an automated computational framework for identification of causal genetic variants (coding/splicing single-nucleotide variants and small insertions and deletions) for rare diseases using WES of families or parent-child trios. eDiVA combines next-generation sequencing data analysis, comprehensive functional annotation, and causal variant prioritization optimized for familial genetic disease studies. eDiVA features a machine learning-based variant pathogenicity predictor combining various genomic and evolutionary signatures. Clinical information, such as disease phenotype or mode of inheritance, is incorporated to improve the precision of the prioritization algorithm. Benchmarking against state-of-the-art competitors demonstrates that eDiVA consistently performed as a good or better than existing approach in terms of detection rate and precision. Moreover, we applied eDiVA to several familial disease cases to demonstrate its clinical applicability.
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Secuenciación del Exoma/métodos , Mutación , Enfermedades Raras/genética , Algoritmos , Bases de Datos Genéticas , Predisposición Genética a la Enfermedad , Humanos , Aprendizaje Automático , Padres , Navegador WebRESUMEN
Collagen XIII is a non-fibrillar transmembrane collagen which has been long recognized for its critical role in synaptic maturation of the neuromuscular junction. More recently, biallelic COL13A1 loss-of-function mutations were identified in three patients with congenital myasthenic syndrome (CMS), a rare inherited condition with defective neuromuscular transmission, causing abnormal fatigability and fluctuating muscle weakness and often successfully treated with acetylcholinesterase inhibitors. Here we report six additional CMS patients from three unrelated families with previously unreported homozygous COL13A1 loss-of-function mutations (p.Tyr216*, p.Glu543fs and p.Thr629fs). The phenotype of our cases was similar to the previously reported patients including respiratory distress and severe dysphagia at birth that often resolved or improved in the first days or weeks of life. All individuals had prominent eyelid ptosis with only minor ophthalmoparesis as well as generalized muscle weakness, predominantly affecting facial, bulbar, respiratory and axial muscles. Response to acetylcholinesterase inhibitor treatment was generally negative while salbutamol proved beneficial. Our data further support the causality of COL13A1 variants for CMS and suggest that this type of CMS might be clinically homogenous and requires alternative pharmacological therapy.
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Colágeno Tipo XIII/genética , Mutación/genética , Síndromes Miasténicos Congénitos/genética , Niño , Consanguinidad , Análisis Mutacional de ADN , Salud de la Familia , Femenino , Humanos , Masculino , Síndromes Miasténicos Congénitos/patología , Síndromes Miasténicos Congénitos/fisiopatología , Receptor trkA/genética , Adulto JovenRESUMEN
INTRODUCTION: The manner in which imaging patterns change over the disease course and with increasing disability in dysferlinopathy is not fully understood. METHODS: Fibroadipose infiltration of 61 muscles was scored based on whole-body MRI of 33 patients with dysferlinopathy and represented in a heatmap. We trained random forests to predict disease duration, Motor Function Measure dimension 1 (MFM-D1), and modified Rankin scale (MRS) score based on muscle scoring and selected the most important muscle for predictions. RESULTS: The heatmap delineated positive and negative fingerprints in dysferlinopathy. Disease duration was related to infiltration of infraspinatus, teres major-minor, and supraspinatus muscles. MFM-D1 decreased with higher infiltration of teres major-minor, triceps, and sartorius. MRS related to infiltration of vastus medialis, gracilis, infraspinatus, and sartorius. DISCUSSION: Dysferlinopathy shows a recognizable muscle MRI pattern. Fibroadipose infiltration in specific muscles of the thigh and the upper limb appears to be an important marker for disease progression. Muscle Nerve 59:436-444, 2019.
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Evaluación de la Discapacidad , Músculo Esquelético/diagnóstico por imagen , Distrofia Muscular de Cinturas/diagnóstico por imagen , Tejido Adiposo/patología , Adulto , Femenino , Fibrosis/diagnóstico por imagen , Fibrosis/patología , Humanos , Aprendizaje Automático , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Manguito de los Rotadores/diagnóstico por imagen , Adulto JovenRESUMEN
INTRODUCTION: Particular fibroadipose infiltration patterns have been recently described by muscle imaging in congenital and later onset forms of LMNA-related muscular dystrophies (LMNA-RD). METHODS: Scores for fibroadipose infiltration of 23 lower limb muscles in 34 patients with LMNA-RD were collected from heat maps of 2 previous studies. Scoring systems were homogenized. Relationships between muscle infiltration and disease duration and age of onset were modeled with random forests. RESULTS: The pattern of infiltration differs according to disease duration but not to age of disease onset. The muscles whose progression best predicts disease duration were semitendinosus, biceps femoris long head, gluteus medius, and semimembranosus. DISCUSSION: In LMNA-RD, our synthetic analysis of lower limb muscle infiltration did not find major differences between forms with different ages of onset but allowed the identification of muscles with characteristic infiltration during disease progression. Monitoring of these specific muscles by quantitative MRI may provide useful imaging biomarkers in LMNA-RD. Muscle Nerve 58:812-817, 2018.
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Imagen por Resonancia Magnética , Músculo Esquelético/diagnóstico por imagen , Atrofia Muscular Espinal/diagnóstico por imagen , Adolescente , Adulto , Anciano , Niño , Estudios de Cohortes , Progresión de la Enfermedad , Extremidades/diagnóstico por imagen , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estadísticas no Paramétricas , Tomografía Computarizada por Rayos X , Adulto JovenRESUMEN
OBJECTIVES: To characterise the pattern and spectrum of involvement on muscle MRI in a large cohort of patients with sarcoglycanopathies, which are limb-girdle muscular dystrophies (LGMD2C-2F) caused by mutations in one of the four genes coding for muscle sarcoglycans. METHODS: Lower limb MRI scans of patients with LGMD2C-2F, ranging from severe childhood variants to milder adult-onset forms, were collected in 17 neuromuscular referral centres in Europe and USA. Muscle involvement was evaluated semiquantitatively on T1-weighted images according to a visual score, and the global pattern was assessed as well. RESULTS: Scans from 69 patients were examined (38 LGMD2D, 18 LGMD2C, 12 LGMD2E and 1 LGMD2F). A common pattern of involvement was found in all the analysed scans irrespective of the mutated gene. The most and earliest affected muscles were the thigh adductors, glutei and posterior thigh groups, while lower leg muscles were relatively spared even in advanced disease. A proximodistal gradient of involvement of vasti muscles was a consistent finding in these patients, including the most severe ones. CONCLUSIONS: Muscle involvement on MRI is consistent in patients with LGMD2C-F and can be helpful in distinguishing sarcoglycanopathies from other LGMDs or dystrophinopathies, which represent the most common differential diagnoses. Our data provide evidence about selective susceptibility or resistance to degeneration of specific muscles when one of the sarcoglycans is deficient, as well as preliminary information about progressive involvement of the different muscles over time.
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Imagen por Resonancia Magnética/métodos , Sarcoglicanopatías/genética , Sarcoglicanos/genética , Adolescente , Adulto , Niño , Preescolar , Europa (Continente) , Femenino , Humanos , Masculino , Persona de Mediana Edad , Músculo Esquelético/patología , Mutación , Fenotipo , Sarcoglicanos/deficiencia , Estados UnidosRESUMEN
Fas Apoptosis Inhibitory Molecule (FAIM) is an evolutionarily highly conserved death receptor antagonist, widely expressed and known to participate in physiological and pathological processes. Two FAIM transcript variants have been characterized to date, namely FAIM short (FAIM-S) and FAIM long (FAIM-L). FAIM-S is ubiquitously expressed and serves as an anti-apoptotic protein in the immune system. Furthermore, in neurons, this isoform promotes NGF-induced neurite outgrowth through NF-кB and ERK signaling. In contrast FAIM-L is found only in neurons, where it exerts anti-apoptotic activity against several stimuli. In addition to these two variants, in silico studies point to the existence of two additional isoforms, neither of which have been characterized to date. In this regard, here we confirm the presence of these two additional FAIM isoforms in human fetal brain, fetal and adult testes, and placenta tissues. We named them FAIM-S_2a and FAIM-L_2a since they have the same sequence as FAIM-S and FAIM-L, but include exon 2a. PCR and western blot revealed that FAIM-S_2a shows ubiquitous expression in all the tissues and cellular models tested, while FAIM-L_2a is expressed exclusively in tissues of the nervous system. In addition, we found that, when overexpressed in non-neuronal cells, the splicing factor nSR100 induces the expression of the neuronal isoforms, thus identifying it as responsible for the generation of FAIM-L and FAIM-L_2a. Functionally, FAIM-S_2a and FAIM-L_2a increased neurite outgrowth in response to NGF stimulation in a neuronal model. This observation thus, supports the notion that these two isoforms are involved in neuronal differentiation. Furthermore, subcellular fractionation experiments revealed that, in contrast to FAIM-S and FAIM-L, FAIM-S_2a and FAIM-L_2a are able to localize to the nucleus, where they may have additional functions. In summary, here we report on two novel FAIM isoforms that may have relevant roles in the physiology and pathology of the nervous system.
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Proteínas Reguladoras de la Apoptosis/metabolismo , Isoformas de Proteínas/metabolismo , Empalme Alternativo , Animales , Proteínas Reguladoras de la Apoptosis/química , Proteínas Reguladoras de la Apoptosis/genética , Línea Celular , Exones , Humanos , Conformación de Ácido Nucleico , Células PC12 , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Estabilidad Proteica , ARN Mensajero/química , ARN Mensajero/genética , Ratas , Reacción en Cadena en Tiempo Real de la Polimerasa , TermodinámicaRESUMEN
Biallelic GLDN mutations have recently been identified among infants with lethal congenital contracture syndrome 11 (LCCS11). GLDN encodes gliomedin, a protein required for the formation of the nodes of Ranvier and development of the human peripheral nervous system. We report six infants and children from four unrelated families with biallelic GLDN mutations, four of whom survived beyond the neonatal period into infancy, childhood, and late adolescence with intensive care and chronic respiratory and nutritional support. Our findings expand the genotypic and phenotypic spectrum of LCCS11 and demonstrate that the condition may not necessarily be lethal in the neonatal period.
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Artrogriposis/diagnóstico , Artrogriposis/genética , Genes Letales , Proteínas de la Membrana/genética , Mutación , Proteínas del Tejido Nervioso/genética , Fenotipo , Artrogriposis/mortalidad , Biopsia , Análisis Mutacional de ADN , Resultado Fatal , Estudios de Asociación Genética , Humanos , Lactante , Recién Nacido , Masculino , Linaje , Raíces Nerviosas Espinales/ultraestructura , Secuenciación del ExomaRESUMEN
Microcephaly with simplified gyration, epilepsy and permanent neonatal diabetes syndrome (MEDS) is a recently described, autosomal recessive-inherited syndrome. We report the case of an infant presenting with lethargy at age five weeks and clinical findings of persistent hyperglycaemia and microcephaly with simplified gyration, suggestive of MEDS. The diagnosis was confirmed by the detection of a known c.233 T > C mutation in the IER3IP1 gene. Only eight cases of MEDS have been reported in the literature. We reviewed these with the aim of better delineating their clinical manifestations, which should allow earlier and more accurate diagnosis and genetic counseling.
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Proteínas Portadoras/genética , Diabetes Mellitus/genética , Epilepsia/genética , Proteínas de la Membrana/genética , Microcefalia/genética , Diabetes Mellitus/diagnóstico , Epilepsia/diagnóstico , Humanos , Lactante , Masculino , Microcefalia/diagnóstico , Mutación Puntual , SíndromeRESUMEN
Enterovirus D68 was known to be the cause of mild to severe respiratory infections, but in the last few years, it has also been associated with myelitis and paralysis. This report describes the first Enterovirus D68 detections in acute flaccid paralysis cases occurring between December 2015 and March 2016 in Spain.