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The von Willebrand Factor A domain containing 1 protein, encoded by VWA1, is an extracellular matrix protein expressed in muscle and peripheral nerve. It interacts with collagen VI and perlecan, two proteins that are affected in hereditary neuromuscular disorders. Lack of VWA1 is known to compromise peripheral nerves in a Vwa1 knock-out mouse model. Exome sequencing led us to identify bi-allelic loss of function variants in VWA1 as the molecular cause underlying a so far genetically undefined neuromuscular disorder. We detected six different truncating variants in 15 affected individuals from six families of German, Arabic, and Roma descent. Disease manifested in childhood or adulthood with proximal and distal muscle weakness predominantly of the lower limbs. Myopathological and neurophysiological findings were indicative of combined neurogenic and myopathic pathology. Early childhood foot deformity was frequent, but no sensory signs were observed. Our findings establish VWA1 as a new disease gene confidently implicated in this autosomal recessive neuromyopathic condition presenting with child-/adult-onset muscle weakness as a key clinical feature.
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Proteínas da Matriz Extracelular/genética , Doenças Neuromusculares/genética , Adolescente , Adulto , Criança , Feminino , Predisposição Genética para Doença , Humanos , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/patologia , Mutação , Doenças Neuromusculares/patologia , Linhagem , Sequenciamento do ExomaRESUMO
OBJECTIVE: To test the hypothesis that monogenic neuropathies such as Charcot-Marie-Tooth disease (CMT) contribute to frequent but often unexplained neuropathies in the elderly, we performed genetic analysis of 230 patients with unexplained axonal neuropathies and disease onset ≥35 years. METHODS: We recruited patients, collected clinical data, and conducted whole-exome sequencing (WES; n = 126) and MME single-gene sequencing (n = 104). We further queried WES repositories for MME variants and measured blood levels of the MME-encoded protein neprilysin. RESULTS: In the WES cohort, the overall detection rate for assumed disease-causing variants in genes for CMT or other conditions associated with neuropathies was 18.3% (familial cases 26.4%, apparently sporadic cases 12.3%). MME was most frequently involved and accounted for 34.8% of genetically solved cases. The relevance of MME for late-onset neuropathies was further supported by detection of a comparable proportion of cases in an independent patient sample, preponderance of MME variants among patients compared to population frequencies, retrieval of additional late-onset neuropathy patients with MME variants from WES repositories, and low neprilysin levels in patients' blood samples. Transmission of MME variants was often consistent with an incompletely penetrant autosomal-dominant trait and less frequently with autosomal-recessive inheritance. CONCLUSIONS: A detectable fraction of unexplained late-onset axonal neuropathies is genetically determined, by variants in either CMT genes or genes involved in other conditions that affect the peripheral nerves and can mimic a CMT phenotype. MME variants can act as completely penetrant recessive alleles but also confer dominantly inherited susceptibility to axonal neuropathies in an aging population.
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Envelhecimento , Neuropatia Hereditária Motora e Sensorial/genética , Neprilisina/genética , Idade de Início , Idoso , Envelhecimento/sangue , Doença de Charcot-Marie-Tooth/sangue , Doença de Charcot-Marie-Tooth/genética , Feminino , Predisposição Genética para Doença/genética , Neuropatia Hereditária Motora e Sensorial/sangue , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Masculino , Pessoa de Meia-Idade , Neprilisina/sangue , Sequenciamento do ExomaRESUMO
Charcot-Marie-Tooth disease type 1A, caused by a duplication of the gene peripheral myelin protein 22 kDa, is the most frequent subtype of hereditary peripheral neuropathy with an estimated prevalence of 1:5000. Patients suffer from sensory deficits, muscle weakness and foot deformities. There is no treatment approved for this disease. Outcome measures in clinical trials were based mainly on clinical features but did not evaluate the actual nerve damage. In our case-control study, we aimed to provide objective and reproducible outcome measures for future clinical trials. We collected skin samples from 48 patients with Charcot-Marie-Tooth type 1A, 7 patients with chronic inflammatory demyelinating polyneuropathy, 16 patients with small fibre neuropathy and 45 healthy controls. To analyse skin innervation, 40-µm cryosections of glabrous skin taken from the lateral index finger were double-labelled by immunofluorescence. The disease severity of patients with Charcot-Marie-Tooth type 1A was assessed by the Charcot-Marie-Tooth neuropathy version 2 score, which ranged from 3 (mild) to 27 (severe) and correlated with age (P < 0.01, R = 0.4). Intraepidermal nerve fibre density was reduced in patients with Charcot-Marie-Tooth type 1A compared with the healthy control group (P < 0.01) and negatively correlated with disease severity (P < 0.05, R = -0.293). Meissner corpuscle (MC) density correlated negatively with age in patients with Charcot-Marie-Tooth type 1A (P < 0.01, R = -0.45) but not in healthy controls (P = 0.07, R = 0.28). The density of Merkel cells was reduced in patients with Charcot-Marie-Tooth type 1A compared with healthy controls (P < 0.05). Furthermore, in patients with Charcot-Marie-Tooth type 1A, the fraction of denervated Merkel cells was highly increased and correlated with age (P < 0.05, R = 0.37). Analysis of nodes of Ranvier revealed shortened paranodes and a reduced fraction of long nodes in patients compared with healthy controls (both P < 0.001). Langerhans cell density was increased in chronic inflammatory demyelinating polyneuropathy, but not different in Charcot-Marie-Tooth type 1A compared with healthy controls. Our data suggest that intraepidermal nerve fibre density might be used as an outcome measure in Charcot-Marie-Tooth type 1A disease, as it correlates with disease severity. The densities of Meissner corpuscles and Merkel cells might be an additional tool for the evaluation of the disease progression. Analysis of follow-up biopsies will clarify the effects of Charcot-Marie-Tooth type 1A disease progression on cutaneous innervation.
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OBJECTIVE: To clarify the prevalence, long-term natural history, and severity determinants of SEPN1-related myopathy (SEPN1-RM), we analyzed a large international case series. METHODS: Retrospective clinical, histologic, and genetic analysis of 132 pediatric and adult patients (2-58 years) followed up for several decades. RESULTS: The clinical phenotype was marked by severe axial muscle weakness, spinal rigidity, and scoliosis (86.1%, from 8.9 ± 4 years), with relatively preserved limb strength and previously unreported ophthalmoparesis in severe cases. All patients developed respiratory failure (from 10.1±6 years), 81.7% requiring ventilation while ambulant. Histopathologically, 79 muscle biopsies showed large variability, partly determined by site of biopsy and age. Multi-minicores were the most common lesion (59.5%), often associated with mild dystrophic features and occasionally with eosinophilic inclusions. Identification of 65 SEPN1 mutations, including 32 novel ones and the first pathogenic copy number variation, unveiled exon 1 as the main mutational hotspot and revealed the first genotype-phenotype correlations, bi-allelic null mutations being significantly associated with disease severity (p = 0.017). SEPN1-RM was more severe and progressive than previously thought, leading to loss of ambulation in 10% of cases, systematic functional decline from the end of the third decade, and reduced lifespan even in mild cases. The main prognosis determinants were scoliosis/respiratory management, SEPN1 mutations, and body mass abnormalities, which correlated with disease severity. We propose a set of severity criteria, provide quantitative data for outcome identification, and establish a need for age stratification. CONCLUSION: Our results inform clinical practice, improving diagnosis and management, and represent a major breakthrough for clinical trial readiness in this not so rare disease.
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Genótipo , Proteínas Musculares/genética , Doenças Musculares/diagnóstico por imagem , Doenças Musculares/genética , Selenoproteínas/genética , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Doenças Musculares/patologia , Estudos Retrospectivos , Adulto JovemRESUMO
Patients with the neurological disorder HSAN-I suffer frequent infections, attributed to a lack of pain sensation and failure to seek care for minor injuries. Whether protective CD8+ T cells are affected in HSAN-I patients remains unknown. Here, we report that HSAN-I-associated mutations in serine palmitoyltransferase subunit SPTLC2 dampened human T cell responses. Antigen stimulation and inflammation induced SPTLC2 expression, and murine T-cell-specific ablation of Sptlc2 impaired antiviral-T-cell expansion and effector function. Sptlc2 deficiency reduced sphingolipid biosynthetic flux and led to prolonged activation of the mechanistic target of rapamycin complex 1 (mTORC1), endoplasmic reticulum (ER) stress, and CD8+ T cell death. Protective CD8+ T cell responses in HSAN-I patient PBMCs and Sptlc2-deficient mice were restored by supplementing with sphingolipids and pharmacologically inhibiting ER stress-induced cell death. Therefore, SPTLC2 underpins protective immunity by translating extracellular stimuli into intracellular anabolic signals and antagonizes ER stress to promote T cell metabolic fitness.
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Linfócitos T CD8-Positivos/imunologia , Neuropatias Hereditárias Sensoriais e Autônomas/genética , Coriomeningite Linfocítica/imunologia , Vírus da Coriomeningite Linfocítica/imunologia , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Serina C-Palmitoiltransferase/genética , Animais , Proliferação de Células , Células Cultivadas , Citocinas/biossíntese , Estresse do Retículo Endoplasmático/genética , Estresse do Retículo Endoplasmático/imunologia , Feminino , Humanos , Coriomeningite Linfocítica/virologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Transdução de Sinais/imunologia , Esfingolipídeos/biossínteseRESUMO
MPV17 encodes a putative channel-forming protein of the inner mitochondrial membrane and is involved in mitochondrial deoxynucleotide homeostasis. MPV17 mutations were first reported in patients with Navajo neurohepatopathy, an autosomal recessive mitochondrial DNA depletion syndrome, characterized by early-onset liver failure, failure to thrive as well as central and peripheral neurological involvement. Recently, two patients with juvenile-onset peripheral sensorimotor neuropathy associated with an MVP17 c.122G>A (p.Arg41Gln) variant have been reported. Here, we describe five additional patients from two unrelated families with sensorimotor axonal neuropathy without hepatocerebral affection caused by homozygous MPV17 variants. Patients of the first family carried the known c.122G>A variant and affected individuals of the second family had a novel c.376-9T>G near-splice variant, which was shown to result in an in-frame deletion of 11 amino acids. This report provides further evidence that MPV17 mutations should be considered in patients with pure, non-syndromic axonal neuropathy.
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Predisposição Genética para Doença , Proteínas de Membrana/genética , Proteínas Mitocondriais/genética , Doenças do Sistema Nervoso Periférico/genética , Polineuropatias/genética , Adolescente , Adulto , Idade de Início , Axônios/patologia , Criança , Insuficiência de Crescimento/genética , Insuficiência de Crescimento/fisiopatologia , Feminino , Transtornos Heredodegenerativos do Sistema Nervoso/genética , Transtornos Heredodegenerativos do Sistema Nervoso/fisiopatologia , Humanos , Hepatopatias/genética , Hepatopatias/fisiopatologia , Falência Hepática/genética , Falência Hepática/fisiopatologia , Masculino , Doenças Mitocondriais/genética , Doenças Mitocondriais/fisiopatologia , Doenças do Sistema Nervoso Periférico/fisiopatologia , Polineuropatias/fisiopatologia , Córtex Sensório-Motor/fisiopatologia , Adulto JovemRESUMO
This paper is a practical survey of immune-mediated, inflammatory and hereditary neuropathies along with recommendations for diagnostic procedures. The large group of immune-mediated, inflammatory neuropathies includes the Guillain-Barré syndrome and chronic-inflammatory demyelinating polyradiculoneuropathy and their subtypes, vasculitic, paraneoplastic and paraproteinemic neuropathies as well as neuropathies resulting from connective tissue disorders. Besides clinical features such as time-dependent progression and distribution of sensorimotor deficits, characteristic electroneurographic findings and antibody profiles are considered. Recent studies in hereditary neuropathies reveal a prevalence of 10-28 out of 100 000 persons in Europe. Research into the genetic causes has made significant progress in the last 20 years; up to now more than 80 genes mutated in hereditary neuropathies have been identified. Besides classification into axonal, demyelinating or intermediate neuropathies based on electroneurography, distinguishing between sensorimotor, pure motor and (autonomous) sensory neuropathies as well as consideration of particular clinical features and ethnic origin can be helpful in orientating molecular genetic analysis.
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Algoritmos , Neuropatia Hereditária Motora e Sensorial/diagnóstico , Neuropatia Hereditária Motora e Sensorial/imunologia , Neuropatia Hereditária Motora e Sensorial/terapia , HumanosRESUMO
BACKGROUND: Charcot-Marie-Tooth disease type 1A (CMT1A) is the most common inherited neuropathy, a debilitating disease without known cure. Among patients with CMT1A, disease manifestation, progression and severity are strikingly variable, which poses major challenges for the development of new therapies. Hence, there is a strong need for sensitive outcome measures such as disease and progression biomarkers, which would add powerful tools to monitor therapeutic effects in CMT1A. METHODS: We established a pan-European and American consortium comprising nine clinical centres including 311 patients with CMT1A in total. From all patients, the CMT neuropathy score and secondary outcome measures were obtained and a skin biopsy collected. In order to assess and validate disease severity and progression biomarkers, we performed qPCR on a set of 16 animal model-derived potential biomarkers in skin biopsy mRNA extracts. RESULTS: In 266 patients with CMT1A, a cluster of eight cutaneous transcripts differentiates disease severity with a sensitivity and specificity of 90% and 76.1%, respectively. In an additional cohort of 45 patients with CMT1A, from whom a second skin biopsy was taken after 2-3 years, the cutaneous mRNA expression of GSTT2, CTSA, PPARG, CDA, ENPP1 and NRG1-Iis changing over time and correlates with disease progression. CONCLUSIONS: In summary, we provide evidence that cutaneous transcripts in patients with CMT1A serve as disease severity and progression biomarkers and, if implemented into clinical trials, they could markedly accelerate the development of a therapy for CMT1A.
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Doença de Charcot-Marie-Tooth/terapia , Progressão da Doença , Marcadores Genéticos/genética , Pele/patologia , Resultado do Tratamento , Adulto , Idoso , Biópsia , Catepsina A/genética , Doença de Charcot-Marie-Tooth/sangue , Doença de Charcot-Marie-Tooth/genética , Feminino , Glutationa Transferase/genética , Glicoproteínas/genética , Humanos , Masculino , Pessoa de Meia-Idade , Neuregulina-1/genética , Proteínas Nucleares , PPAR gama/genética , Diester Fosfórico Hidrolases/genética , Prognóstico , Pirofosfatases/genética , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Transcrição Gênica/genéticaRESUMO
Hereditary neuropathies comprise a wide variety of chronic diseases associated to more than 80 genes identified to date. We herein examined 612 index patients with either a Charcot-Marie-Tooth phenotype, hereditary sensory neuropathy, familial amyloid neuropathy, or small fiber neuropathy using a customized multigene panel based on the next generation sequencing technique. In 121 cases (19.8%), we identified at least one putative pathogenic mutation. Of these, 54.4% showed an autosomal dominant, 33.9% an autosomal recessive, and 11.6% an X-linked inheritance. The most frequently affected genes were PMP22 (16.4%), GJB1 (10.7%), MPZ, and SH3TC2 (both 9.9%), and MFN2 (8.3%). We further detected likely or known pathogenic variants in HINT1, HSPB1, NEFL, PRX, IGHMBP2, NDRG1, TTR, EGR2, FIG4, GDAP1, LMNA, LRSAM1, POLG, TRPV4, AARS, BIC2, DHTKD1, FGD4, HK1, INF2, KIF5A, PDK3, REEP1, SBF1, SBF2, SCN9A, and SPTLC2 with a declining frequency. Thirty-four novel variants were considered likely pathogenic not having previously been described in association with any disorder in the literature. In one patient, two homozygous mutations in HK1 were detected in the multigene panel, but not by whole exome sequencing. A novel missense mutation in KIF5A was considered pathogenic because of the highly compatible phenotype. In one patient, the plasma sphingolipid profile could functionally prove the pathogenicity of a mutation in SPTLC2. One pathogenic mutation in MPZ was identified after being previously missed by Sanger sequencing. We conclude that panel based next generation sequencing is a useful, time- and cost-effective approach to assist clinicians in identifying the correct diagnosis and enable causative treatment considerations.
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Predisposição Genética para Doença , Neuropatia Hereditária Motora e Sensorial/genética , Mutação/genética , Doenças Raras/genética , Doença de Charcot-Marie-Tooth/genética , Feminino , Proteínas de Choque Térmico HSP27/genética , Proteínas de Choque Térmico , Neuropatia Hereditária Motora e Sensorial/diagnóstico , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Humanos , Masculino , Chaperonas Moleculares , FenótipoRESUMO
Apart from infectious causes and cerebellar dysfunction associated with acquired immune deficiency syndrome dementia or HIV-associated neurocognitive disorder, cerebellar dysfunction in HIV-positive individuals has been ascribed to granule cell neuronopathy as well as primary cerebellar atrophy without identifiable etiology. We report the case of a patient with progressive cerebellar dysfunction as the primary manifestation of HIV infection. No symptom improvement was seen under combination antiretroviral therapy, which had been established upon diagnosis, but the patient improved rapidly under 4-aminopyridine treatment, which was recommended 1 year later. Our report, adding to the rather small number of reports of HIV-associated cerebellar atrophy and dysfunction as a primary manifestation of HIV infection, draws attention to HIV as a possible differential etiology of a cerebellar syndrome. Further, rapid improvement of symptom severity under 4-aminopyridine treatment warrants further investigation with longer-term follow-up into the effectiveness of this compound in gait disorder associated with HIV infection.
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Axonal polyneuropathies are a frequent cause of progressive disability in the elderly. Common etiologies comprise diabetes mellitus, paraproteinaemia, and inflammatory disorders, but often the underlying causes remain elusive. Late-onset axonal Charcot-Marie-Tooth neuropathy (CMT2) is an autosomal-dominantly inherited condition that manifests in the second half of life and is genetically largely unexplained. We assumed age-dependent penetrance of mutations in a so far unknown gene causing late-onset CMT2. We screened 51 index case subjects with late-onset CMT2 for mutations by whole-exome (WES) and Sanger sequencing and subsequently queried WES repositories for further case subjects carrying mutations in the identified candidate gene. We studied nerve pathology and tissue levels and function of the abnormal protein in order to explore consequences of the mutations. Altogether, we observed heterozygous rare loss-of-function and missense mutations in MME encoding the metalloprotease neprilysin in 19 index case subjects diagnosed with axonal polyneuropathies or neurodegenerative conditions involving the peripheral nervous system. MME mutations segregated in an autosomal-dominant fashion with age-related incomplete penetrance and some affected individuals were isolated case subjects. We also found that MME mutations resulted in strongly decreased tissue availability of neprilysin and impaired enzymatic activity. Although neprilysin is known to degrade ß-amyloid, we observed no increased amyloid deposition or increased incidence of dementia in individuals with MME mutations. Detection of MME mutations is expected to increase the diagnostic yield in late-onset polyneuropathies, and it will be tempting to explore whether substances that can elevate neprilysin activity could be a rational option for treatment.
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Axônios/patologia , Genes Dominantes/genética , Mutação/genética , Neprilisina/genética , Polineuropatias/genética , Polineuropatias/patologia , Tecido Adiposo/metabolismo , Adulto , Idade de Início , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/genética , Alelos , Peptídeos beta-Amiloides/metabolismo , Animais , Doença de Charcot-Marie-Tooth/complicações , Doença de Charcot-Marie-Tooth/genética , Doença de Charcot-Marie-Tooth/patologia , Análise Mutacional de DNA , Bases de Dados Genéticas , Demência/complicações , Demência/genética , Exoma/genética , Heterozigoto , Humanos , Camundongos , Pessoa de Meia-Idade , Mutação de Sentido Incorreto/genética , Neprilisina/análise , Neprilisina/sangue , Neprilisina/deficiência , Penetrância , Polineuropatias/complicações , Pele/metabolismo , Nervo SuralRESUMO
OBJECTIVE: We prospectively screened a large European cohort of patients presenting with hyperCKemia and/or limb-girdle muscular weakness (LGMW) for acid α-glucosidase (GAA) deficiency by dried blood spot (DBS) investigation. METHODS: DBS were collected from 3,076 consecutive adult patients from 7 German and British neuromuscular centers. All specimens were investigated for GAA deficiency by fluorometry. Samples with reduced enzyme activity were subsequently investigated for GAA gene mutations. RESULTS: Of 3,076 patients with DBS samples, 232 patients (7.6%) showed low GAA enzyme activity. Of these 232 patients, 55 (24%) presented with isolated hyperCKemia and 176 (76%) with hyperCKemia and LGMW. With both features present, 94% of the patients showed a low enzymatic activity. Mutational analysis found GAA gene mutations in 74 patients (2.4%); herein 70 patients were heterozygote for the common GAA gene splice-site mutation c.-32-13T>G. The most common clinical presentation in the confirmed Pompe cohort was a limb-girdle phenotype (85.3%) combined with ventilatory insufficiency (61%). Isolated hyperCKemia was found in 12%, while 2.7 had hyperCKemia and ventilatory insufficiency only. CONCLUSIONS: In a large cohort of unselected adult patients with hyperCKemia and/or LGMW, we found a prevalence of late-onset Pompe disease of 2.4%. Therefore, targeted screening of such a population should be encouraged in clinical practice.
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Doença de Depósito de Glicogênio Tipo II/complicações , Doença de Depósito de Glicogênio Tipo II/epidemiologia , Distrofia Muscular do Cíngulo dos Membros/complicações , alfa-Glucosidases/sangue , alfa-Glucosidases/deficiência , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Creatina Quinase/sangue , Teste em Amostras de Sangue Seco , Feminino , Alemanha/epidemiologia , Doença de Depósito de Glicogênio Tipo II/sangue , Doença de Depósito de Glicogênio Tipo II/genética , Humanos , Masculino , Pessoa de Meia-Idade , Distrofia Muscular do Cíngulo dos Membros/enzimologia , Distrofia Muscular do Cíngulo dos Membros/epidemiologia , Distrofia Muscular do Cíngulo dos Membros/genética , Mutação , Fenótipo , Prevalência , Reino Unido/epidemiologia , Adulto Jovem , alfa-Glucosidases/genéticaRESUMO
Hereditary sensory and autonomic neuropathy 1 (HSAN1) is an autosomal dominant disorder that can be caused by variants in SPTLC1 or SPTLC2, encoding subunits of serine palmitoyl-CoA transferase. Disease variants alter the enzyme's substrate specificity and lead to accumulation of neurotoxic 1-deoxysphingolipids. We describe two families with autosomal dominant HSAN1C caused by a new variant in SPTLC2, c.547C>T, p.(Arg183Trp). The variant changed a conserved amino acid and was not found in public variant databases. All patients had a relatively mild progressive distal sensory impairment, with onset after age 50. Small fibers were affected early, leading to abnormalities on quantitative sensory testing. Sural biopsy revealed a severe chronic axonal neuropathy with subtotal loss of myelinated axons, relatively preserved number of non-myelinated fibers and no signs for regeneration. Skin biopsy with PGP9.5 labeling showed lack of intraepidermal nerve endings early in the disease. Motor manifestations developed later in the disease course, but there was no evidence of autonomic involvement. Patients had elevated serum 1-deoxysphingolipids, and the variant protein produced elevated amounts of 1-deoxysphingolipids in vitro, which proved the pathogenicity of the variant. Our results expand the genetic spectrum of HSAN1C and provide further detail about the clinical characteristics. Sequencing of SPTLC2 should be considered in all patients presenting with mild late-onset sensory-predominant small or large fiber neuropathy.
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Neuropatias Hereditárias Sensoriais e Autônomas/genética , Transtornos de Início Tardio/genética , Mutação de Sentido Incorreto , Serina C-Palmitoiltransferase/genética , Idade de Início , Idoso , Sequência de Aminoácidos , Substituição de Aminoácidos , Axônios/patologia , Feminino , Finlândia , Genes Dominantes , Alemanha , Haplótipos , Humanos , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Linhagem , Serina C-Palmitoiltransferase/deficiência , Serina C-Palmitoiltransferase/metabolismo , Neuropatia de Pequenas Fibras/genética , Esfingolipídeos/sangue , Especificidade por SubstratoRESUMO
This study evaluates primary and secondary clinical outcome measures in Charcot-Marie-Tooth disease type 1A (CMT1A) with regard to their contribution towards discrimination of disease severity. The nine components of the composite Charcot-Marie-Tooth disease Neuropathy Score and six additional secondary clinical outcome measures were assessed in 479 adult patients with genetically proven CMT1A and 126 healthy controls. Using hierarchical clustering, we identified four significant clusters of patients according to clinical severity. We then tested the impact of each of the CMTNS components and of the secondary clinical parameters with regard to their power to differentiate these four clusters. The CMTNS components ulnar sensory nerve action potential (SNAP), pin sensibility, vibration and strength of arms did not increase the discriminant value of the remaining five CMTNS components (Ulnar compound motor action potential [CMAP], leg motor symptoms, arm motor symptoms, leg strength and sensory symptoms). However, three of the six additional clinical outcome measures - the 10m-timed walking test (T10MW), 9 hole-peg test (9HPT), and foot dorsal flexion dynamometry - further improved discrimination between severely and mildly affected patients. From these findings, we identified three different composite measures as score hypotheses and compared their discriminant power with that of the CMTNS. A composite of eight components CMAP, Motor symptoms legs, Motor symptoms arms, Strength of Legs, Sensory symptoms), displayed the strongest power to discriminate between the clusters. As a conclusion, five items from the CMTNS and three secondary clinical outcome measures improve the clinical assessment of patients with CMT1A significantly and are beneficial for upcoming clinical and therapeutic trials.
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Antioxidantes/uso terapêutico , Ácido Ascórbico/uso terapêutico , Doença de Charcot-Marie-Tooth/diagnóstico , Doença de Charcot-Marie-Tooth/tratamento farmacológico , Avaliação de Resultados em Cuidados de Saúde , Índice de Gravidade de Doença , Adolescente , Adulto , Fatores Etários , Doença de Charcot-Marie-Tooth/genética , Doença de Charcot-Marie-Tooth/terapia , Análise por Conglomerados , Estudos de Coortes , Progressão da Doença , Método Duplo-Cego , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Força Muscular , Medição da Dor , Desempenho Psicomotor/fisiologia , Caminhada , Adulto JovemRESUMO
BACKGROUND: Dysferlinopathies are autosomal recessive disorders caused by mutations in the dysferlin (DYSF) gene encoding the dysferlin protein. DYSF mutations lead to a wide range of muscular phenotypes, with the most prominent being Miyoshi myopathy (MM) and limb girdle muscular dystrophy type 2B (LGMD2B). METHODS: We assessed the one-year-natural course of dysferlinopathy, and the safety and efficacy of deflazacort treatment in a double-blind, placebo-controlled cross-over trial. After one year of natural course without intervention, 25 patients with genetically defined dysferlinopathy were randomized to receive deflazacort and placebo for six months each (1 mg/kg/day in month one, 1 mg/kg every 2nd day during months two to six) in one of two treatment sequences. RESULTS: During one year of natural course, muscle strength declined about 2% as measured by CIDD (Clinical Investigation of Duchenne Dystrophy) score, and 76 Newton as measured by hand-held dynamometry. Deflazacort did not improve muscle strength. In contrast, there is a trend of worsening muscle strength under deflazacort treatment, which recovers after discontinuation of the study drug. During deflazacort treatment, patients showed a broad spectrum of steroid side effects. CONCLUSION: Deflazacort is not an effective therapy for dysferlinopathies, and off-label use is not warranted. This is an important finding, since steroid treatment should not be administered in patients with dysferlinopathy, who may be often misdiagnosed as polymyositis. TRIAL REGISTRATION: This clinical trial was registered at http://www.ClincalTrials.gov, identifier: NCT00527228, and was always freely accessible to the public.
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Anti-Inflamatórios/uso terapêutico , Distrofia Muscular do Cíngulo dos Membros/tratamento farmacológico , Pregnenodionas/uso terapêutico , Adolescente , Adulto , Estudos Cross-Over , Método Duplo-Cego , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Atividade Motora , Força Muscular , Distrofia Muscular do Cíngulo dos Membros/fisiopatologia , Placebos , Qualidade de Vida , Adulto JovemRESUMO
Charcot-Marie-Tooth disease is the most common inherited neuropathy and a duplication of the peripheral myelin protein 22 gene causes the most frequent subform Charcot-Marie-Tooth 1A. Patients develop a slowly progressive dysmyelinating and demyelinating peripheral neuropathy and distally pronounced muscle atrophy. The amount of axonal loss determines disease severity. Although patients share an identical monogenetic defect, the disease progression is strikingly variable and the impending disease course can not be predicted in individual patients. Despite promising experimental data, recent therapy trials have failed. Established clinical outcome measures are thought to be too insensitive to detect amelioration within trials. Surrogate biomarkers of disease severity in Charcot-Marie-Tooth 1A are thus urgently needed. Peripheral myelin protein 22 transgenic rats harbouring additional copies of the peripheral myelin protein 22 gene ('Charcot-Marie-Tooth rats'), which were kept on an outbred background mimic disease hallmarks and phenocopy the variable disease severity of patients with Charcot-Marie-Tooth 1A. Hence, we used the Charcot-Marie-Tooth rat to dissect prospective and surrogate markers of disease severity derived from sciatic nerve and skin tissue messenger RNA extracts. Gene set enrichment analysis of sciatic nerve transcriptomes revealed that dysregulation of lipid metabolism associated genes such as peroxisome proliferator-activated receptor gamma constitutes a modifier of present and future disease severity. Importantly, we directly validated disease severity markers from the Charcot-Marie-Tooth rats in 46 patients with Charcot-Marie-Tooth 1A. Our data suggest that the combination of age and cutaneous messenger RNA levels of glutathione S-transferase theta 2 and cathepsin A composes a strong indicator of disease severity in patients with Charcot-Marie-Tooth 1A, as quantified by the Charcot-Marie-Tooth Neuropathy Score. This translational approach, utilizing a transgenic animal model, demonstrates that transcriptional analysis of skin biopsy is suitable to identify biomarkers of Charcot-Marie-Tooth 1A.
Assuntos
Axônios/patologia , Doença de Charcot-Marie-Tooth/patologia , Proteínas da Mielina/genética , Nervo Isquiático/patologia , Animais , Axônios/fisiologia , Doença de Charcot-Marie-Tooth/genética , Doença de Charcot-Marie-Tooth/fisiopatologia , Modelos Animais de Doenças , Glutationa Transferase/genética , Proteína P0 da Mielina/genética , Condução Nervosa/fisiologia , PPAR gama/genética , Medição da Dor , Fenótipo , Ratos , Ratos Transgênicos , Nervo Isquiático/fisiopatologia , Índice de Gravidade de DoençaRESUMO
Hereditary sensory and autonomic neuropathy type I (HSAN-I) is an axonal peripheral neuropathy associated with progressive distal sensory loss and severe ulcerations. Mutations in the first subunit of the enzyme serine palmitoyltransferase (SPT) have been associated with HSAN-I. The SPT enzyme catalyzes the first and rate-limiting step in the de novo sphingolipid synthesis pathway. However, different studies suggest the implication of other genes in the pathology of HSAN-I. Therefore, we screened the two other known subunits of SPT, SPTLC2 and SPTLC3, in a cohort of 78 HSAN patients. No mutations were found in SPTLC3, but we identified three heterozygous missense mutations in the SPTLC2 subunit of SPT in four families presenting with a typical HSAN-I phenotype. We demonstrate that these mutations result in a partial to complete loss of SPT activity in vitro and in vivo. Moreover, they cause the accumulation of the atypical and neurotoxic sphingoid metabolite 1-deoxy-sphinganine. Our findings extend the genetic heterogeneity in HSAN-I and enlarge the group of HSAN neuropathies associated with SPT defects. We further show that HSAN-I is consistently associated with an increased formation of the neurotoxic 1-deoxysphinganine, suggesting a common pathomechanism for HSAN-I.
Assuntos
Neuropatias Hereditárias Sensoriais e Autônomas/genética , Serina C-Palmitoiltransferase/genética , Sequência de Bases , Linhagem Celular , Clonagem Molecular , Estudos de Coortes , Análise Mutacional de DNA , Primers do DNA/genética , Teste de Complementação Genética , Humanos , Repetições de Microssatélites/genética , Dados de Sequência Molecular , Mutação de Sentido Incorreto/genética , Serina C-Palmitoiltransferase/metabolismoRESUMO
Spinal muscular atrophies (SMA, also known as hereditary motor neuropathies) and hereditary motor and sensory neuropathies (HMSN) are clinically and genetically heterogeneous disorders of the peripheral nervous system. Here we report that mutations in the TRPV4 gene cause congenital distal SMA, scapuloperoneal SMA, HMSN 2C. We identified three missense substitutions (R269H, R315W and R316C) affecting the intracellular N-terminal ankyrin domain of the TRPV4 ion channel in five families. Expression of mutant TRPV4 constructs in cells from the HeLa line revealed diminished surface localization of mutant proteins. In addition, TRPV4-regulated Ca(2+) influx was substantially reduced even after stimulation with 4alphaPDD, a TRPV4 channel-specific agonist, and with hypo-osmotic solution. In summary, we describe a new hereditary channelopathy caused by mutations in TRPV4 and present evidence that the resulting substitutions in the N-terminal ankyrin domain affect channel maturation, leading to reduced surface expression of functional TRPV4 channels.
Assuntos
Repetição de Anquirina , Neuropatia Hereditária Motora e Sensorial/genética , Atrofia Muscular Espinal/congênito , Atrofia Muscular Espinal/genética , Mutação/genética , Canais de Cátion TRPV/química , Canais de Cátion TRPV/genética , Substituição de Aminoácidos/genética , Cálcio/metabolismo , Células HeLa , Neuropatia Hereditária Motora e Sensorial/complicações , Neuropatia Hereditária Motora e Sensorial/fisiopatologia , Humanos , Imuno-Histoquímica , Espaço Intracelular/metabolismo , Ativação do Canal Iônico , Modelos Moleculares , Dados de Sequência Molecular , Atrofia Muscular Espinal/complicações , Atrofia Muscular Espinal/fisiopatologia , Proteínas Mutantes/metabolismo , Osmose , TransfecçãoRESUMO
Emery-Dreifuss muscular dystrophy (EDMD) is a heterogeneous late-onset disease involving skeletal muscle wasting and heart defects caused, in a minority of cases, by mutations in either of two genes encoding the inner nuclear membrane (INM) proteins, emerin and lamins A/C. Nesprin-1 and -2 are multi-isomeric, spectrin-repeat proteins that bind both emerin and lamins A/C and form a network in muscle linking the nucleoskeleton to the INM, the outer nuclear membrane, membraneous organelles, the sarcomere and the actin cytoskeleton. Thus, disruptions in nesprin/lamin/emerin interactions might play a role in the muscle-specific pathogenesis of EDMD. Screening for DNA variations in the genes encoding nesprin-1 (SYNE1) and nesprin-2 (SYNE2) in 190 probands with EDMD or EDMD-like phenotypes identified four heterozygous missense mutations. Fibroblasts from these patients exhibited nuclear morphology defects and specific patterns of emerin and SUN2 mislocalization. In addition, diminished nuclear envelope localization of nesprins and impaired nesprin/emerin/lamin binding interactions were common features of all EDMD patient fibroblasts. siRNA knockdown of nesprin-1 or -2 in normal fibroblasts reproduced the nuclear morphological changes and mislocalization of emerin and SUN2 observed in patient fibroblasts. Taken together, these data suggest that EDMD may be caused, in part, by uncoupling of the nucleoskeleton and cytoskeleton because of perturbed nesprin/emerin/lamin interactions.
Assuntos
Proteínas dos Microfilamentos/genética , Distrofia Muscular de Emery-Dreifuss/genética , Proteínas do Tecido Nervoso/genética , Proteínas Nucleares/genética , Sequência de Aminoácidos , Sequência de Bases , Linhagem Celular , Proteínas do Citoesqueleto , DNA/genética , Análise Mutacional de DNA , Feminino , Fibroblastos/metabolismo , Fibroblastos/ultraestrutura , Heterozigoto , Humanos , Laminas/genética , Laminas/metabolismo , Masculino , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteínas dos Microfilamentos/metabolismo , Microscopia Eletrônica de Transmissão , Dados de Sequência Molecular , Músculo Esquelético/metabolismo , Distrofia Muscular de Emery-Dreifuss/etiologia , Distrofia Muscular de Emery-Dreifuss/metabolismo , Mutação de Sentido Incorreto , Proteínas do Tecido Nervoso/metabolismo , Membrana Nuclear/metabolismo , Proteínas Nucleares/metabolismo , Linhagem , RNA Interferente Pequeno/genética , Homologia de Sequência de AminoácidosRESUMO
OBJECTIVE: Distal hereditary motor neuropathy type V (dHMN-V) and Charcot-Marie-Tooth syndrome (CMT) type 2 presenting with predominant hand involvement, also known as CMT2D and Silver syndrome (SS) are rare phenotypically overlapping diseases which can be caused by mutations in the Berardinelli-Seip Congenital Lipodystrophy 2 (BSCL2) and in the glycyl-tRNA synthetase encoding (GARS) genes. Mutations in the heat-shock proteins HSPB1 and HSPB8 can cause related distal hereditary motor neuropathies (dHMN) and are considered candidates for dHMN-V, CMT2, and SS. DESIGN: To define the frequency and distribution of mutations in the GARS, BSCL2, HSPB1 and HSPB8 genes we screened 33 unrelated sporadic and familial patients diagnosed as either dHMN-V, CMT2D or SS. Exon 3 of the BSCL2 gene was screened in further 69 individuals with an unclassified dHMN phenotype or diagnosed as hereditary spastic paraplegia (HSP) complicated by pure motor neuropathy. RESULTS: Four patients diagnosed with dHMN-V or SS carried known heterozygous BSCL2 mutations (N88S and S90L). In one dHMN-V patient we detected a putative GARS mutation (A57V). No mutations were detected in HSPB1 and HSPB8. The diagnostic yield gained in the series of 33 probands was 12% for BSCL2 mutations and 3% for GARS mutations. In the series of unclassified dHMN and complicated HSP cases no mutations were found. CONCLUSIONS: Our data confirm that most likely only two mutations (N88S, S90L) in exon 3 of BSCL2 may lead to dHMN-V or SS phenotypes. Mutations in GARS, HSPB1 and HSPB8. are not a common cause of dHMN-V, SS and CMT2D. We would therefore suggest that a genetic testing of dHMN-V and SS patients should begin with screening of exon 3 of the BSCL2 gene. Screening of the GARS gene is useful in patients with CMT2 with predominant hand involvement and dHMN-V. The rather low frequencies of BSCL2, GARS, HSPB1 and HSPB8 mutations in dHMN-V, CMT2D and SS patients strongly point to further genetic heterogeneity of these related disorders.