DGH - Posters/abstracts em congressos internacionais
Permanent URI for this collection
Browse
Recent Submissions
- The role of UPF1 cap-independent translation in colorectal cancerPublication . Lacerda, Rafaela; Menezes,Juliane; Elias, Adriana; Sousa, Sofia de; Romão, LuísaColorectal cancer (CRC) is one of the deadliest diseases worldwide with projections pointing towards an increase for the next two decades. Translation dysregulation of many genes contributes to CRC development, and here we are studying the role of translation dysregulation of up-frameshift 1 (UPF1) in CRC. This protein is involved in many cellular mechanisms such as nonsense-mediated mRNA decay, cell cycle progression, or telomere maintenance and homeostasis. It also works as a tumour suppressor protein in most cancers but not in CRC, in which UPF1 plays an oncogenic role. We used the Xena platform to perform in silico analyses that revealed UPF1 protein overexpressed in CRC, contrary to several other analysed cancers. Besides, UPF1 protein levels are increased in CRC compared to the counterpart normal tissues. Experimentally, we confirmed that UPF1 protein expression is maintained in different CRC cell lines under normal conditions or endoplasmic reticulum (ER) stress. To understand the mechanism underlying such maintenance, we used a bicistronic reporter construct to test whether UPF1 5’ untranslated region (UTR) can mediate alternative translation initiation and we concluded that such sequence drives cap-independent translation initiation, in both normal and stress conditions. Deletional and mutational analyses of UPF1 5’UTR showed that nucleotides 1–100 [stem-loop (SL) I] and 151–275 (SL III) — out of 275 nucleotides — are the minimal required sequences for the cap-independent translation initiation mechanism to work properly. Using RNA antisense oligonucleotides (ASOs) targeting UPF1 SL I and III, we observed a reduced UPF1 expression in HCT116 (CRC) cells, supporting the functional role of SL I and SL III in mediating cap-independent translation. Altogether, these results highlight the importance of cap-independent translation initiation in UPF1 expression regulation, in conditions that mimic the tumour microenvironment, and this might be used as a therapeutic target.
- Relevance of Multigene Panels in the Molecular diagnosis of patients with disorders of sexual developmentPublication . Pereira-Caetano, Iris; Mendonça, Joana; Mirante, Alice; Cardoso, Rita; Rodrigues, Márcia; Oliveira, João Paulo; Grangeia, Ana; Barbosa, David; Vieira, Luís; Gonçalves, JoãoIntroduction: Next generation sequencing (NGS) is increasingly used in the molecular diagnosis of rare diseases, such as disorders of sexual development (DSD), allowing the analysis of a greater number of genes in a single assay, providing faster results with reduced costs. DSD patients may present high phenotypic overlap (genital ambiguity, sex reversal, delayed/absent puberty, infertility) posing challenges to clinical diagnosis. NGS technology using multigene panels has higher hypothesis to identify the genetic cause and novel genetic variants in a large number of cases. Methodology: 33 genomic DNA samples from DSD patients were sequenced on MiSeq using the Ampliseq technology (Illumina). A customized gene panel covering 40 genes was used to prepare the libraries of the target sequences. The 40 genes were subdivided into 5 subpanels: primary sex determination, sex differentiation, hypogonadotropic hypogonadism/infertility, steroidogenesis and premature ovarian insufficiency. Variant classification, according to ACMG-AMP, was based on bioinformatics tools (ex. VEP, HSF, VarSome, Alamut) and databases (gnomAD, HGMD, ClinVar, dbSNP). Pathogenic, Likely pathogenic and VUS variants were confirmed by Sanger sequencing. Results: 16 of the 33 patients were previously studied in our laboratory with negative results for the main genes associated with DSD (SRY, AR, ANOS1, GNRHR, CYP21A2). We identified 9 causative variants (8P/1LP) in 7 patients (21.2%) in AR, HSD17B3, LHCGR, FGFR1 and NR5A1. One patient was a compound heterozygous for HSD17B3 and another simultaneously homozygous for LHCGR and hemizygous for AR. The remaining 5 were homozigous, heterozigous or hemizygous for HSD17B3, LHCGR, NR5A1, FGFR1 or AR. One VUS, FGFR1:c.566G>A p.Arg189His, requires familial studies to revaluate its pathogenicity. Discussion: Multigene NGS studies allows to increase the rate of variant detection, mainly in genes not included in a first molecular approach. It also contributes to establishing or confirming the clinical diagnosis, assisting in decisions regarding the treatment and reproductive management of patients and families, as well as in genetic counselling.
- Molecular characterization of a new CYP21A2 allele and classification of its pathogenicityPublication . Gomes, Susana; Saraiva, Jorge; Gonçalves, JoãoBackground: The CYP21A2 gene, coding for 21-Hydroxylase (21-OH), is located on 6p21.3 within the major histocompatibility complex, and integrated in a cluster of genes (RP1, C4A, C4B, TNXB) and pseudogenes (RP2, CYP21A1P, TNXA). This genomic region is variable in size and gene copy number. Due to the high homology between genes and their pseudogenes, recombination is common, deletions, insertions and duplications are frequent. The great diversity of this cluster and rare alleles contributes to additional difficulties on molecular analysis and pathogenicity classification. Methods: The CYP21A cluster was characterized using genomic DNA obtained from four healthy brothers (parents not available). Two long-PCR products, specific for each CYP21A2 copy of a trimodular allele (with two CYP21A2 copies), and for a normal/bimodular allele present in this family, were characterized by Sanger cycling sequencing and MLPA (MRC-Holland, P050-C1 kit). Results: The molecular studies revealed that one sister, who asked for genetic counselling, has a very rare trimodular allele, with two CYP21A2 genes. One of these genes has a deletion covering exons 4 to 7 and an insertion of exons 4 to 7 of the pseudogene (CYP21A1P) which has the pathogenic variants c.518T>A, c.710T>A, c.713T>A, c.719T>A, c.844G>T and c.923dupT, all in phase. This alteration can be described as: CYP21A2ex4_7delinsCYP21A1Pex4_7. Conclusion: The developed molecular approach, which was specifically designed for this family and included segregation analysis of all brothers, allowed the characterization of a new CYP21A2 trimodular allele that, even containing six pathogenic variants, is non-pathogenic as it also has (in phase) a normal CYP21A2 copy.
- Reclassification of BRCA1/2 variants previously classified as VUS (ACMG-AMP guidelines) with gene-specific guidelines from ClinGen ENIGMA and CanVIG-UKPublication . Rodrigues, Pedro; Theisen, Patrícia; Gonçalves, JoãoIn recent years, the number of BRCA1/2 germline variants associated with hereditary breast/ovarian cancer syndrome (HBOC), classified as variants of uncertain significance (VUS) according to ACMG-AMP guidelines (ACMGg) has been increasing. Reclassification of VUS as (likely) benign or (likely) pathogenic is crucial for maximizing diagnostic yield and appropriately managing HBOC patients. Recently, specific guidelines to improve classification of BRCA1/2 variants were independently developed by ClinGen ENIGMA1 (CG-Eg) and CanVIG-UK2 (CV-UKg). Main goals: i) independently reclassify BRCA1/2 variants previously classified as VUS (ACMGg) with the new guidelines (CG-Eg and CV-UKg); ii) compare the results between the different guidelines iii) evaluate the potential clinical impact of this reclassification. BRCA1/2 germline variants identified in patients with suspected HBOC and previously classified as VUS (8 missense, 5 intronic) were independently reclassified according to CG-Eg and CV-UKg. Variant assessment included: query of clinical/population databases and use of VEP, Alamut, VarSome and Franklin-Genoox. VUS reclassification (using CG-Eg versus CV-UKg) was in agreement for 10 variants (2 VUS, 6 likely benign (LB) and 2 benign (B)). The remaining 3 VUS were reclassified as LB with CG-Eg and kept as VUS with CV-UK. Application of specific guidelines reduced the number of VUS from 10 to 2 (CG-Eg) or to 5 (CV-UKg). The main difference between CG-Eg and CV-UKg is related with the downgrading strength of PM2 and the upgrading strength of BP1 criteria (in CG-Eg) for missense variants present outside clinically important functional domains and without splicing impact. The difference in BP1 strength has a major impact, making CG-Eg more stringent and reducing the number of VUS. The use of different guidelines, even if gene-specific, can lead to dissimilar classifications, a general consensus leading to a unique international guideline will be useful.
- Exploring an antisense oligonucleotide exon-skipping therapeutic strategy for Mucolipidosis IIPublication . Matos, Liliana; Gonçalves, Mariana; Santos, Juliana Inês; Coutinho, Maria Francisca; Prata, Maria João; Omidi, Maryam; Pohl, Sandra; Alves, SandraIntroduction: Mucolipidosis II (ML II) is a Lysosomal Storage Disorder caused by the deficiency of the enzyme GlcNAc-1-phosphotransferase, which is responsible for the Mannose-6-Phosphate marker addition to lysosomal enzymes. Of all ML II mutations, the c.3503_3504delTC in GNPTAB exon 19 is the most frequent, making it a good target for a personalized therapy. Here, we explored an innovative therapeutic strategy based on the use of antisense oligonucleotides (ASOs) for ML II. Previously, on ML II patients’ fibroblasts, ASOs were used to skip exon 19 of the GNPTAB pre-mRNA, successfully resulting in the production of an in-frame mRNA. Now, our aim is to analyze if these results are translated to the enzymatic and cellular phenotype level.
- An Antisense Oligonucletide based therapy for a rare disease: in vitro and in vivo studiesPublication . Gonçalves, M.; Matos, L.; Santos, J.I.; Coutinho, M.F.; Prata, M.J.; Pires, M.J.; Oliveira, P.A.; Alves, SandraMucolipidosis type II (ML II) is a Lysosomal Storage Disorder caused by the deficiency of the enzyme GlcNAc-1-phosphotransferase. This enzyme is responsible for the addition of the mannose-6-phosphate marker to lysosomal enzymes allowing their targeting to lysosomes. From the several ML II mutations, the deletion of two nucleotides from GNPTAB exon 19 (c.3503_3504del) is the most frequent, making it a good target for a mutation specific therapy. In this study, we explored an innovative therapeutic strategy based on the use of antisense oligonucleotides (ASOs) for ML II. In a previous study1 on fibroblasts from ML II patients, ASOs were used to skip exon 19 of the GNPTAB pre-mRNA, successfully resulting in the production of an in-frame mRNA. Currently, our objective is to evaluate the therapeutic potential of this approach, both in vitro in C57BL/6 fibroblasts and in vivo in C57BL/6 mice.
- Antisense oligonucleotide exon-skipping as a therapeutic approach for a rare diseasePublication . Gonçalves, Mariana; Matos, Liliana; Santos, Juliana I.; Coutinho, Maria Francisca; Prata, Maria João; Pires, Maria João; Oliveira, Paula; Omidi, Maryam; Pohl, Sandra; Alves, SandraMucolipidosis II (MLII) is a Lysosomal Storage Disorder caused by the deficiency of the enzyme GlcNAc-1-phosphotransferase, which is responsible for the Mannose- 6-Phosphate marker addition to lysosomal enzymes. Of all MLII mutations, the c.3503_3504delTC in GNPTAB exon 19 is the most frequent, making it a good target for a personalized therapy. Here, we explored an innovative therapeutic strategy based on the use of antisense oligonucleotides (ASOs) for MLII. Previously, on MLII patients’ fibroblasts, ASOs were used to skip exon 19 of the GNPTAB pre-mRNA, successfully resulting in the production of an in-frame mRNA[1]. Now, our aim is to analyze if these results are translated to the enzymatic and cellular phenotype level.
- Study of the contribution of modulators of iron homeostasis in heart failurePublication . Matias, Ana; Santos, Mafalda; Aguia, Laura; Mascarenhas, Mário Rui; Barbosa, Mário; Melício, Ana; Menezes Falcão, Luiz; Faustino, Paula; Manuel, Bicho; Inácio, ÂngelaIntroduction: Heart failure (HF) is considered one of the biggest public health problems, affecting 2% of the world's population. Is defined as a clinical syndrome due to a structural and/or functional abnormality of the heart that results in elevated intracardiac pressures and/or inadequate cardiac output at rest and/or during exercise. It can be influenced by several genetic modulators, in particular genes responsible for the balance of iron (Fe) metabolism, such as the HFE, SLC40A1 and TMPRSS6 genes. Aims: To investigate the contribution of common genetic variants in HFE (C282Y - rs1800562 and H63D - rs1799945), SLC40A1 (rs1439816 and rs2304704) and TMPRSS6 (rs855791) to HF. Material and Methods: The study included a population of 301 HF patients and 361 controls. The polymorphic analysis of the HFE gene variants (C282Y and H63D) was realized using the Multiplex PCR-ARMS technique, while the Endpoint Genotyping PCR technique was used for the remaining variants. Statistical analysis was done using SPSS software, version 28.0, with a statistical significance level of p<0.05. Results: Statistically significant differences were found between patients and controls, in relation to the frequency of the C282Y genotypes. The presence of the Y allele [OR (CI, 95) = 3.127 (1.223-7.995); p = 0.017] was considered a risk factor for HF development. Discussion: Based on the results obtained, the HFE gene was shown to modulate HF. This investigation not only provides a better understanding of the role of HFE in the etiology of HF and is a step forward in personalized medicine, but also underlines the importance of the iron homeostasis in HF. It proposes and reaffirms that the study of iron – related biomarkers as well as HFE common variants should be performed in patients with HF.
- Genetic testing for germline variants in homologous recombination repair genes, other than BRCA1 and BRCA2, in patients with suspected hereditary cancer syndromesPublication . Arnaut, Daniela; Rodrigues, Pedro; Theisen, Patrícia; Carpinteiro, Dina; Vieira, Luís; Gonçalves, JoãoHomologous recombination repair (HRR) is the cellular mechanism for error-free repair of DNA double-strand breaks. Pathogenic germline variants in BRCA1 and BRCA2 lead to HRR deficiency associated with breast, ovarian, prostate, pancreatic cancers and are sensitive to PARP inhibitors (PARPi). Defects in HRR genes beyond BRCA1/2 could also result in HRR deficiency and sensitize the tumor to PARPi, thus expanding the subset of patients that can benefit from these targeted therapy cancer drugs. We studied 56 DNA samples obtained from patients with personal and family history of cancer. Genes involved in HRR (ATM, BAP1, BLM, BRIP1, FANCA, FANCB, FANCC, FANCD2, FANCE, FANCF, FANCG, FANCI, FANCL, FANCM, NBN, PALB2, RAD51C, RAD51D) were analysed by NGS using TruSight® Hereditary Cancer. Sequence alignment and annotation included DRAGEN Enrichment and Variant Interpreter - Illumina®. Variant classification, according to ACMG-AMP 1, was based on VEP, HSF, Alamut, VarSome and several databases (ex. HGMD, gnomAD, dbSNP). Variants of uncertain significance (VUS) were also classified with the stepwise ABC system2. All pathogenic/likely pathogenic SNVs and CNVs were confirmed by Sanger sequencing or MLPA. We identified 156 SNVs and one CNV, of these 125 were benign/likely benign. Seven clinically actionable variants were found in 10.7% of the patients: 3 pathogenic variants in FANCA, FANCD2 and FANCI give rise to premature stop codons and one pathogenic CNV in FANCA (deletion of exons 38 and 39); 2 likely pathogenic variants in BLM and FANCI affecting splicing and one frameshift in FANCG. Classification of 18 VUS with the ABC system resulted in: 8 class 0 (normal finding), 7 class E (potential interest) and 3 class D (low penetrance) variants. In addition, 7 SNVs were classified as hypomorphic alleles. This study confirmed: i) the importance of extending the molecular study beyond BRCA1/2 to other genes involved in HRR, ii) some variants require functional/family studies to establish their pathogenicity, and iii) these genes could potentially be considered for specific and clinical studies involving PARPi therapy.
- Multiple non contiguous copy gains and a terminal loss in 8q24 identified in a fetus with cleft palate and lipPublication . Serafim, S.; Pedro, S.; Marques, B.; Tarelho, A.R.; Ferreira, C.; Simao, L.; Viegas, M.; Silva, M.; Alves, C.; Mourinha, V.; Ferreira, A.; Correia, H.Objectives: Chromosomal microarray analysis (CMA) is the recommended genetic test in pregnancies with ultrasound abnormalities but in some cases karyotype may still be needed to clarify the underlying mechanism of complex rearrangements. Here we report the case of a fetus from a healthy 24-year-old G1P0 woman, with a low risk for common aneuploidies in the 1st trimester prenatal screening but referred for CMA at 17+6 weeks of gestation due to cleft palate and lip in the 1st trimester ultrasound. Method: After a normal result in the rapid aneuploidy diagnostic test we performed CMA using ThermoFisher Cytoscan™ 750K. Our reporting resolution includes gains and losses larger than 35 Kb, considered clinically relevant for the course of the pregnancy. In this case further tests were done to assess recurrence risk and a possible chromosomal rearrangement: CMA and karyotype on the parents and karyotype on the fetus. Results: The CMA profile revealed a female fetus with three non-contiguous interstitial copy gains and a terminal loss in the long arm of chromosome 8 (8q24), as follows: - x4 copy gain at 8q24.12q24.13 with 585 Kb - x2 copy neutral region with 1.5 Mb - x4 copy gain at 8q24.13 with 2.9 Mb - x2 copy neutral region with 1.2 Mb - x3 copy gain at 8q24.21q24.23 with 17.8 Mb - x1 terminal loss at 8q24.3 with 130 Kb The fetal karyotype showed, in one of the chromosomes 8, an abnormal pattern in the long arm with a larger relative size. After parental studies the reported copy number variants were shown to be de novo. Conclusions. Most of the cases reported in the literature with gains along 8q result from a rearrangement involving another chromosome making it challenging to assess a genotype-phenotype correlation (PMID: 34265769; PMID: 31141803; PMID: 34794751). The few cases of individuals reported with isolated gains in the 8q24 have been described as having different features, depending on the size of the gain, and those may include facial dysmorphysms, clef lip and palate, developmental delay, among others (PMID: 25506438; PMID: 11484205; PMID: 33316910; UNIQUE - rarechromo.org: duplications of 8q). Recently a fetus with multiple congenital abnormalities, including clef palate, was reported having a similar imbalance, and although the parents decided to keep the pregnancy the baby died soon after birth given the extension of the congenital abnormalities (PMID: 30638476). The CMA results in our case explained the clef palate and lip identified in the fetus and, after genetic counseling, the parents opted to terminate the pregnancy. Although the identified non-contiguous gains and the terminal loss may suggest a mechanism of chromothripsis/chromoanagenesis for the arising of this abnormal chromosome 8, no further studies were performed after determining that the parents had a normal result and therefore a low recurrence risk for future pregnancies.