Browsing by Author "Duarte, S"
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- Analysis of Synaptic Proteins in the Cerebrospinal Fluid as a New Tool in the Study of Inborn Errors of NeurotransmissionPublication . Duarte, S; Ortez, C; Pérez, A; Artuch, R; García-Cazorla, AAbstract In a few rare diseases, specialised studies in cerebrospinal fluid (CSF) are required to identify the underlying metabolic disorder. We aimed to explore the possibility of detecting key synaptic proteins in the CSF, in particular dopaminergic and gabaergic, as new procedures that could be useful for both pathophysiological and diagnostic purposes in investigation of inherited disorders of neurotransmission. Dopamine receptor type 2 (D2R), dopamine transporter (DAT) and vesicular monoamine transporter type 2 (VMAT2) were analysed in CSF samplesfrom 30 healthy controls (11 days to 17 years) by western blot analysis. Because VMAT2 was the only protein with intracellular localisation, and in order to compare results, GABA vesicular transporter, which is another intracellular protein, was also studied. Spearman’s correlation and Student’s t tests were applied to compare optical density signals between different proteins. All these synaptic proteins could be easily detected and quantified in the CSF. DAT, D2R and GABA VT expression decrease with age, particularly in the first months of life, reflecting the expected intense synaptic activity and neuronal circuitry formation. A statistically significant relationship was found between D2R and DAT expression, reinforcing the previous evidence of DAT regulation by D2R. To our knowledge, there are no previous studies on human CSF reporting a reliable analysis of these proteins. These kinds of studies could help elucidate new causes of disturbed dopaminergic and gabaergic transmission as well as understanding different responses to L-dopa in inherited disorders affecting dopamine metabolism. Moreover, this approach to synaptic activity in vivo can be extended to different groups of proteins and diseases.
- Atypical Phenotype in Two Patients with LAMA2 MutationsPublication . Marques, J; Duarte, S; Costa, S; Jacinto, S; Oliveira, J; Oliveira, M; Santos, R; Bronze-da-Rocha, E; Silvestre, AR; Calado, E; Evangelista, TCongenital muscular dystrophy type 1A is caused by mutations in the LAMA2 gene, which encodes the a2-chain of laminin. We report two patients with partial laminin-a2 deficiency and atypical phenotypes, one with almost exclusive central nervous system involvement (cognitive impairment and refractory epilepsy) and the second with marked cardiac dysfunction, rigid spine syndrome and limb-girdle weakness. Patients underwent clinical, histopathological, imaging and genetic studies. Both cases have two heterozygous LAMA2 variants sharing a potentially pathogenic missense mutation c.2461A>C (p.Thr821Pro) located in exon 18. Brain MRI was instrumental for the diagnosis, since muscular examination and motor achievements were normal in the first patient and there was a severe cardiac involvement in the second. The clinical phenotype of the patients is markedly different which could in part be explained by the different combination of mutations types (two missense versus a missense and a truncating mutation).
- Case Report: Varicella Associated Neuropsychiatric Syndrome (VANS) in Two Pediatric CasesPublication . Dahiya, D; Matos, CM; Lim, M; Madureira, I; Duarte, S; Byrne, S; Rossor, TBackground: Viral or bacterial infections can trigger auto-immune inflammatory reactions and conditions in children. Self-reactivity arises due to similarities in molecular structures between pathogenic microorganisms and regular body structures with consequent immune-cross reactions. Reactivation of latent Varicella Zoster Virus (VZV) infections can cause neurological sequalae, including cerebellitis, post-herpetic neuralgias, meningo/encephalitis, vasculopathy and myelopathy. We propose a syndrome caused by auto-immune reactivity triggered by molecular mimicry between VZV and the brain, culminating in a post-infectious psychiatric syndrome with childhood VZV infections. Case presentation: Two individuals, a 6-year-old male and 10-year-old female developed a neuro-psychiatric syndrome 3-6 weeks following a confirmed VZV infection with intrathecal oligoclonal bands. The 6-year-old male presented with a myasthenic syndrome, behavior deterioration and regression in school, he was poorly responsive to IVIG and risperidone, however had a pronounced response to steroid treatment. The 10-year-old female presented with marked insomnia, agitation, and behavioral regression as well as mild bradykinesia. A trial of neuroleptics and sedatives resulted in a mild unsustained reduction in psychomotor agitation and IVIG was also unsuccessful, however the patient was very responsive to steroid therapy. Conclusion: Psychiatric syndromes with evidence of intrathecal inflammation temporally related to VZV infections that are responsive to immune modulation have not been described before. Here we report two cases demonstrating neuro-psychiatric symptoms following VZV infection, with evidence of persistent CNS inflammation following the resolution of infection, and response to immune modulation.
- Cerebrospinal Fluid Synaptic Proteins as Useful Biomarkers in Tyrosine Hydroxylase DeficiencyPublication . Ortez, C; Duarte, S; Ormazábal, A; Serrano, M; Pérez, A; Pons, R; Pineda, M; Yapici, Z; Fernández-Álvarez, E; Domingo-Jiménez, R; De Castro, P; Artuch, R; García-Cazorla, ATyrosine hydroxylase (TH) deficiency is an inborn error of dopamine biosynthesis and a cause of early parkinsonism. Two clinical phenotypes have been described. Type “B”: early onset severe encephalopathy; type “A”: later onset, less severe and better response to L-dopa. We aimed to study the expression of several key dopaminergic and gabaergic synaptic proteins in the cerebrospinal fluid (CSF) of a series of patients with TH deficiency and their possible relation with the clinical phenotype and response to L-DOPA. Dopamine transporter (DAT), D2-receptor and vesicularmonoamine transporter (VMAT2)weremeasured in the CSF of 10 subjectswith THdeficiency byWestern blot analysis. In 3 patients, data of pre- and post-treatmentwith L-DOPA were available, and in one of them, GABA vesicular transporter was determined. Results were compared to an age-matched control population. The concentration of D2-receptors in CSFwas significantly higher in patients with TH deficiency than in controls. Similarly, DAT and vesicular monoamine transporter type 2 were up-regulated. Studies performed before LDOPA, and on L-DOPA therapy showed a paradoxical response with D2 receptor expression increase as L-Dopa doses and homovanillic concentration gradually raised in a B phenotype patient. The opposite results were found in two patients with A phenotype. However, this is a very small sample, and further studies are needed to conclude robust differences between phenotypes. Synaptic proteins are detectable in the CSF and their quantification can be useful for understanding the pathophysiology of neurotransmitter defects and potentially to adjust and personalize treatments in the future.
- GNAO1: a new gene to consider on early-onset childhood dystonia]Publication . Marecos, C; Duarte, S; Alonso, I; Calado, E; Moreira, A
- Leigh Syndrome with Atypical Cerebellar LesionsPublication . Veiga, M; Marecos, C; Duarte, S; Vieira, JPLeigh Syndrome is a neurodegenerative disorder caused by mitochondrial dysfunction, with significant phenotypic and genetic heterogeneity. It usually presents in early life, with a severe prognosis. It can be caused by more than 75 different gene mutations, of nuclear and mitochondrial origin, involving all respiratory chain complexes, with less than 25% of Leigh syndrome having mitochondrial DNA mutations. The typical pathologic hallmarks are focal, bilateral, and symmetric lesions in the basal ganglia, thalamus, cerebellum, cerebral white matter and spinal cord gray matter, usually with T2WI and FLAIR hyperintensity. The basal ganglia and thalami frequently present with a pattern of cytotoxic edema. We present one case with clinical and analytical features consistent with Leigh Syndrome, with peculiar imaging features, showing dominant cerebellar edematous changes with unexpected petechial component suggestive of microangiopathy. To our knowledge, these features are unreported and suggest the existence of microvascular lesions. Based on the reported imaging findings, we propose that Leigh Syndrome should be added to the differential diagnosis of acute cerebellitis.
- Modeling Rett Syndrome With Human Patient-Specific Forebrain OrganoidsPublication . Gomes, AR; Fernandes, TG; Vaz, SH; Silva, TP; Bekman, EP; Xapelli, S; Duarte, S; Ghazvini, M; Gribnau, J; Muotri, AR; Trujillo, CA; Sebastião, AM; Cabral, JM; Diogo, MMEngineering brain organoids from human induced pluripotent stem cells (hiPSCs) is a powerful tool for modeling brain development and neurological disorders. Rett syndrome (RTT), a rare neurodevelopmental disorder, can greatly benefit from this technology, since it affects multiple neuronal subtypes in forebrain sub-regions. We have established dorsal and ventral forebrain organoids from control and RTT patient-specific hiPSCs recapitulating 3D organization and functional network complexity. Our data revealed a premature development of the deep-cortical layer, associated to the formation of TBR1 and CTIP2 neurons, and a lower expression of neural progenitor/proliferative cells in female RTT dorsal organoids. Moreover, calcium imaging and electrophysiology analysis demonstrated functional defects of RTT neurons. Additionally, assembly of RTT dorsal and ventral organoids revealed impairments of interneuron's migration. Overall, our models provide a better understanding of RTT during early stages of neural development, demonstrating a great potential for personalized diagnosis and drug screening.
- Primary Disorders of Neurotransmitter Metabolism: Experience of a Tertiary CenterPublication . Duarte, S; Sequeira, S; Rodrigues, R; Calado, ENeurotransmitter diseases are a group of inherited disorders attributable to a disturbance of neurotransmitter metabolism. Biogenic amines are neurotransmitters with multiple roles including psychomotor function, hormone secretion, cardiovascular, respiratory and gastrointestinal control, sleep mechanisms, body temperature and pain. Given the multiple functions of monoamines, disorders of their metabolism comprise a wide spectrum of manifestations, with motor dysfunction being the most prominent clinical feature. Methods: Case review of 12 patients from 4 families, with primary disorders of biogenic amine metabolism. Results: Aromatic L-amino acid decarboxylase deficiency (4 patients from 2 families), and GTP-cyclohydrolase (8 patients from 2 families) were the two diseases identified. Age at first symptoms varied between 2 months and 6 years. Developmental delay was present in all cases except 2 patients with GTP cyclohydrolase deficiency. The combination of axial hypotonia and limb dystonia was also frequent. Children with aromatic L-amino acid decarboxylase deficiency exhibited temperature instability, oculogyric crisis and disturbances of sleep. The index case of one family with GTP cyclohydrolase deficiency presented with Parkinsonism (bradykinesia, rigidity and hypomimia). Analysis of neurotransmitters and their metabolites in CSF was crucial for the identification of index cases. Response to therapy was variable but in general unsatisfactory except in a family with GTP cyclohydrolase deficiency. Conclusions: These disorders should be considered in the differential diagnosis of paediatric neurodegenerative diseases, in order to allow an adequate therapeutic trial that can favor prognosis.
- Pyruvate Dehydrogenase Complex Deficiency: Updating the Clinical, Metabolic and Mutational Landscapes in a Cohort of Portuguese PatientsPublication . Pavlu-Pereira, H; Silva, MJ; Florindo, C; Sequeira, S; Ferreira, AC; Duarte, S; Rodrigues, AL; Janeiro, P; Oliveira, A; Gomes, D; Bandeira, A; Martins, E; Gomes, R; Soares, S; Tavares de Almeida, I; Vicente, JB; Rivera, IBackground: The pyruvate dehydrogenase complex (PDC) catalyzes the irreversible decarboxylation of pyruvate into acetyl-CoA. PDC deficiency can be caused by alterations in any of the genes encoding its several subunits. The resulting phenotype, though very heterogeneous, mainly affects the central nervous system. The aim of this study is to describe and discuss the clinical, biochemical and genotypic information from thirteen PDC deficient patients, thus seeking to establish possible genotype-phenotype correlations. Results: The mutational spectrum showed that seven patients carry mutations in the PDHA1 gene encoding the E1α subunit, five patients carry mutations in the PDHX gene encoding the E3 binding protein, and the remaining patient carries mutations in the DLD gene encoding the E3 subunit. These data corroborate earlier reports describing PDHA1 mutations as the predominant cause of PDC deficiency but also reveal a notable prevalence of PDHX mutations among Portuguese patients, most of them carrying what seems to be a private mutation (p.R284X). The biochemical analyses revealed high lactate and pyruvate plasma levels whereas the lactate/pyruvate ratio was below 16; enzymatic activities, when compared to control values, indicated to be independent from the genotype and ranged from 8.5% to 30%, the latter being considered a cut-off value for primary PDC deficiency. Concerning the clinical features, all patients displayed psychomotor retardation/developmental delay, the severity of which seems to correlate with the type and localization of the mutation carried by the patient. The therapeutic options essentially include the administration of a ketogenic diet and supplementation with thiamine, although arginine aspartate intake revealed to be beneficial in some patients. Moreover, in silico analysis of the missense mutations present in this PDC deficient population allowed to envisage the molecular mechanism underlying these pathogenic variants. Conclusion: The identification of the disease-causing mutations, together with the functional and structural characterization of the mutant protein variants, allow to obtain an insight on the severity of the clinical phenotype and the selection of the most appropriate therapy.