Percorrer por autor "Ribeiro, Diogo"
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- Allelic frequency of CHIT1 variants in the Portuguese populationPublication . Duarte, Ana Joana; Ribeiro, Diogo; Amaral, OlgaChitotriosidase (EC.3.2.1.14) is an enzyme secreted by activated macrophages. This chitinase is useful as a biochemical marker in several lysosomal and nonlysosomal diseases due to its increased activity in such conditions (MIM#600031). In Gaucher Disease type 1 (GD, MIM#230800) patients, the chitotriosidase activity is increased in about 600-fold compared with normal controls. Chitotriosidase is not only useful as a disease severity marker but also measures the effectiveness of the therapy in GD. However, chitotriosidase gene (CHIT1, 1q31-q32) mutations modify the plasma chitotriosidase levels and therefore introduce a degree of variability that can be misleading. The most well known cause of chitotriosidase deficiency is the common 24 bp duplication. Nonetheless, other mutations that occur in this gene also lead to altered catalytic properties. However, as suggested by Bussink and collaborators, slight modifications in assay conditions may help avoiding such problems. In the present work we determined the frequency of two mutations which had appeared in a preliminary screening.
- Applications of iPSCs in Gaucher DiseasePublication . Amaral, Olga; duarte, ana; Ribeiro, Diogo; Santos, Renato; Bragança, JoséIn recent years, human induced pluripotent cell (hiPSC) models have slowly become a trend in experimental modelling of disease, following and complementing animal based models. Human iPSCs provide an innovative manner for modelling Gaucher Disease (GD). Since 2008 several groups have created iPSCs models from GD patients, with various genotypes, and differentiated iPSCs to neural precursors and macrophages among many other types of cells. hiPSC models have been developed from multiple GD donors, recapitulating the disease phenotypic hallmarks. These models have provided a new platform for pathophysiology studies and for the testing of small molecules with therapeutic goals.
- Assessing Lysosomal Disorders in the NGS Era: Identification of Novel Rare VariantsPublication . Encarnação, Marisa; Coutinho, Maria Francisca; Silva, Lisbeth; Ribeiro, Diogo; Ouesleti, Souad; Campos, Teresa; Santos, Helena; Martins, Esmeralda; Cardoso, Maria Teresa; Vilarinho, Laura; Alves, SandraLysosomal storage diseases (LSDs) are a heterogeneous group of genetic disorders with variable degrees of severity and a broad phenotypic spectrum, which may overlap with a number of other conditions. While individually rare, as a group LSDs affect a significant number of patients, placing an important burden on affected individuals and their families but also on national health care systems worldwide. Here, we present our results on the use of an in-house customized next-generation sequencing (NGS) panel of genes related to lysosome function as a first-line molecular test for the diagnosis of LSDs. Ultimately, our goal is to provide a fast and effective tool to screen for virtually all LSDs in a single run, thus contributing to decrease the diagnostic odyssey, accelerating the time to diagnosis. Our study enrolled a group of 23 patients with variable degrees of clinical and/or biochemical suspicion of LSD. Briefly, NGS analysis data workflow, followed by segregation analysis allowed the characterization of approximately 41% of the analyzed patients and the identification of 10 different pathogenic variants, underlying nine LSDs. Importantly, four of those variants were novel, and, when applicable, their effect over protein structure was evaluated through in silico analysis. One of the novel pathogenic variants was identified in the GM2A gene, which is associated with an ultra-rare (or misdiagnosed) LSD, the AB variant of GM2 Gangliosidosis. Overall, this case series highlights not only the major advantages of NGS-based diagnostic approaches but also, to some extent, its limitations ultimately promoting a reflection on the role of targeted panels as a primary tool for the prompt characterization of LSD patients.
- Can Cell-type specific variability be involved in a rare variant of Unverricht-Lundborg? Investigation with iPSC generated modelsPublication . Duarte, Ana Joana; Ribeiro, Diogo; Moreira, Luciana; Amaral, OlgaHomozygosity for a private synonymous mutation in the cystatin-B gene (CSTB, MIM:601145; c.66G>A; p.Q22Q) was detected in a Portuguese patient with a rare, atypical form of Unverricht-Lundborg disease (ULD, MIM #254800). This apparently silent mutation leads to mis-splicing of CSTB pre-mRNA where a normal and an abnormal transcript were detected. Using iPSCs as a source of different cell types, we intend to clarify if the observed abnormal RNA splicing is cell-type specific, and to characterise the subsequent protein mislocalization. In conclusion, we hope to be able to contribute to the understanding of cell-type specific implications in the pathogenesis of ULD.
- Cell lines for the study of Lysosomal Storage Diseases: conservation and identityPublication . Correia, Maria I.; Duarte, Ana J.; Ribeiro, Diogo; Amaral, OlgaThe use of cell lines has revolutionized research in the area of human genetics. The possibility of allowing, at a low cost and relative ease, practical access to biological material bearing in mind the benefit to the patient/family by obtaining samples with adequate informed consent, is a great asset. The accessibility of cell lines from biobanks allows access to samples with all the ethical and feasibility concerns observed. Cell lines are usually cryopreserved in liquid nitrogen and can be maintained in viable conditions for long periods of time. Cell lines allow studies of the causes of the disease, namely: the establishment of cell models, for a better understanding of the pathophysiology; the study of gene interactions; toxicity assays and drug tests; gene editing studies and other types of research. Using fibroblasts from patients with Lysosomal Storage Diseases (LSDs), it was already possible in this laboratory to revert cells to the stem cell state by creating induced pluripotent stem cells (iPSCs) to serve as a model in future studies. This clearly demonstrates the potential of cell lines for research. As with other cell lines, iPSCs can be cryopreserved which increases their potential for use. In order to guarantee the integrity and viability of cryopreserved cell lines, in laboratories, not exclusively dedicated to cell culture (as would be the case of a biobank), it would be advisable to periodically perform random thawing of samples in order to guarantee the identity of the preserved cells, genetic stability and absence of contaminants. There are several ways to do this however, in this work, we present some of the techniques used based on minimal procedures to ensure the cellular integrity of cryopreserved lines. It would be desirable, even in small laboratories, that procedures like these were adopted in a standardized and routine way, to facilitate the success of the subsequent use of cells in research.
- Cellular characterization of normal and mutant cystatin BPublication . Duarte, Ana Joana; Ribeiro, Diogo; Chaves, João; Amaral, OlgaUnverricht- Lundborg disease (ULD or EPM1, MIM 254800), is a myoclonic epilepsy, caused by mutations in the cystatin B gene (CSTB gene) which lead to impaired function of cystatin B compromising its function. The normal protein is an endogenous inhibitor of cysteine proteinases and has several cellular localizations, it is found in the nucleus, cytosol and lysosome. Identification of a rare molecular mechanism causal of Unverricht Lundborg disease in a unique Portuguese patient triggered research in this field. Skin fibroblasts were obtained with informed consent from a homozygous patient with a rare genotype and from a normal control (anonymized). Fibroblast cell cultures were expanded using standard methods. Western Blotting (WB) and immunofluorescence (IF) experiments were carried out following previous described methods (Pinto et al, 2012). For cell fractionation analysis, cells were collected by scraping and suspending in ice-cold phosphate buffer saline (PBS) and cell fractions where obtained using the methods described elsewhere (Suzuki et al, 2010). Immunofluorescence experimental results revealed consistency with the western blot analysis. Although with a decrease of about 4 fold, in relation to normal, cystatin B is clearly present in the cells’ total fraction and in the nuclear fraction. However, in the cytoplasm the decrease seems to be higher which could suggest a subsequent lower protective anti-protease function compromising cellular and lysosomal integrity. Discussion and future perspectives In patient’s fibroblasts the protein quantity is diminished. Although the nuclear location seems to be preserved in the patient´s cells, the cytoplasmic/lysosomal fraction is clearly decreased.
- Characterization of a comon IDUA in the Portuguese populationPublication . Ribeiro, Diogo; Duarte, Ana; Amaral, OlgaMucopolysaccharidosis type I (MPS I; OMIM #252800) is an autosomal recessive disorder, which results from the defective activity of the lysosomal enzyme α-L-iduronidase (IDUA, EC 3.2.1.76). In MPS I, this enzyme deficiency results in a progressive accumulation of the undegraded substrates within tissue lysosomes and fluids, leading to the clinical manifestations of the disease. W402X has been described as common in patients of European Caucasian origin. Moreover, this mutation has been considered to play an important role in terms of the pathophysiology of MPS I. The results of current functional experiments will be presented.
- Characterization of a rare Unverricht-Lundborg disease mutationPublication . Duarte, Ana Joana; Ribeiro, Diogo; Chaves, João; Amaral, OlgaCystatin B (CSTB) gene mutations cause Unverricht–Lundborg disease (ULD), a rare form of myoclonic epilepsy. The previous identification of a Portuguese patient, homozygous for a unique splicing defect (c.66GNA; p.Q22Q), provided awareness regarding the existence of variant forms of ULD. In this work we aimed at the characterization of thismutation at the population level and at the cellular level. The cellular fractionation studies here carried out showed mislocalization of the protein and add to the knowledge on this disease.
- CHIT1 genetic defects in the Portuguese populationPublication . Duarte, Ana; Ribeiro, Diogo; Amaral, OlgaChitotriosidase is an enzyme secreted by activated macrophages and a useful biomarker in several lysosomal and nonlysosomal diseases. However, chitotriosidase gene (CHIT1) mutations may lead to inaccuracy in the significance of this biomarker. Reports on the molecular spectrum of genetic variation in chitotriosidase are rare, and this is one of the few that focus on a specific population group. In this work we assessed the variation of CHIT1 mutations in ten normal controls and detected six missense alterations. G102S, a polymorphism with known altered catalytic properties, was the most frequent being detected in 4/10 individuals. Using allelic discrimination we tested 503 individuals, randomly sampled from the Portuguese population. Variant G102S was detected in 49.5% of the individuals and presented an allele frequency of 0.29. The results of this study showed that variability in CHIT1 gene is considerable and that G102S polymorphism presents a high frequency in the Portuguese.
- Constructing a cardiac cell model from a patient with Fabry diseasePublication . Duarte, Ana Joana; Ribeiro, Diogo; Amaral, Olga• We successfully achieve an iPSC line from a patient with Fabry Disease • Our line has the characteristics of stem cells and has the hability to differentiate into the 3 germ layers • After induction with specific cardiac effectors we achieved beating iPSC-CMs