Percorrer por autor "Gouveia, Nair"
A mostrar 1 - 4 de 4
Resultados por página
Opções de ordenação
- Analysis of paterniy cases with a single exclusion in a genetic marker using precision ID GLOBALFILER™ NGS STR PANEL v2Publication . Gouveia, Nair; Lopes, Virginia; Porto, Maria João; Bento, Ana; Andrade Sampaio, Lisa; Serra, Armando; Balsa, Filipa; Bogas, Vanessa; São Bento, Marta; Amorim, AntónioPaternity test results can sometimes evidence incompatibilities in the allelic transmission from parents to children, such as the presence of a single exclusion in one specific genetic marker, revealing a mismatch between the genetic profiles of the biological parent and the offspring. In these cases, it is important to determine whether the exclusion could be the result of a mutation or other factors as null or silent alleles. Capillary electrophoresis (CE) is the traditional method used in forensic genetics to analyze STRs (Short Tandem Repeats), however it is not possible to know the exact allele number variation due to the lack of sequence data. The application of Next-Generation Sequencing (NGS) technology may provide additional information, since it allows to detect and sequence simultaneously SNPs (Single Nucleotide Polymorphisms) present in the flanking regions and also distinguish isometric alleles with the same length but different sequences, that were misinterpreted as homozygous. In this study, a set of reference samples (buccal swabs and blood stains), previously amplified with the GlobalFiler™ PCR Amplification Kit and sequenced by CE on the 3500 Genetic Analyzer, were selected from paternity cases with a single exclusion, reported after GeneMapper ID-X Software analysis. All samples were automatically prepared with the Precision ID GlobalFiler™ NGS STR Panel v2 on the Ion Chef™ System, followed by sequencing on the Ion S5™ System and finally Converge™ Software analysis, according to the manufacturer’s instructions. The aim was to verify if the NGS methodology provides valuable information in these paternity cases and to identify the parental origin of a mutant allele. The NGS results were in concordance with those obtained by CE. In addition, this methodology demonstrated to be useful to clarify the paternity cases, because it enables a higher power of discrimination through 9 additional multi-allelic STRs, in a total of 35 markers instead of 24 markers of the GlobalFiler™ PCR Amplification Kit used in the traditional method. Therefore, the Precision ID GlobalFiler™ NGS STR Panel v2 shows to be a powerful method for kinship analyses and typing reference samples.
- Microsatellites’ mutation modeling through the analysis of the Y-chromosomal transmission: Results of a GHEP-ISFG collaborative studyPublication . Antão-Sousa, Sofia; Gusmão, Leonor; Modesti, Nidia M.; Feliziani, Sofía; Faustino, Marisa; Marcucci, Valeria; Sarapura, Claudia; Ribeiro, Julyana; Carvalho, Elizeu; Pereira, Vania; Tomas, Carmen; de Pancorbo, Marian M.; Baeta, Miriam; Alghafri, Rashed; Almheiri, Reem; Builes, Juan José; Gouveia, Nair; Burgos, German; Pontes, Lurdes; Ibarra, Adriana; Silva, Cláudia Vieira da; Parveen, Rukhsana; Benitez, Marc; Amorim, Antonio; Pinto, NádiaThe Spanish and Portuguese Speaking Working Group of the International Society for Forensic Genetics (GHEP-ISFG) organized a collaborative study on mutations of Y-chromosomal short tandem repeats (Y-STRs). New data from 2225 father-son duos and data from 44 previously published reports, corresponding to 25,729 duos, were collected and analyzed. Marker-specific mutation rates were estimated for 33 Y-STRs. Although highly dependent on the analyzed marker, mutations compatible with the gain or loss of a single repeat were 23.2 times more likely than those involving a greater number of repeats. Longer alleles (relatively to the modal one) showed to be nearly twice more mutable than the shorter ones. Within the subset of longer alleles, the loss of repeats showed to be nearly twice more likely than the gain. Conversely, shorter alleles showed a symmetrical trend, with repeat gains being twofold more frequent than reductions. A positive correlation between the paternal age and the mutation rate was observed, strengthening previous findings. The results of a machine learning approach, via logistic regression analyses, allowed the establishment of algebraic formulas for estimating the probability of mutation depending on paternal age and allele length for DYS389I, DYS393 and DYS627. Algebraic formulas could also be established considering only the allele length as predictor for DYS19, DYS389I, DYS389II-I, DYS390, DYS391, DYS393, DYS437, DYS439, DYS449, DYS456, DYS458, DYS460, DYS481, DYS518, DYS533, DYS576, DYS626 and DYS627 loci. For the remaining Y-STRs, a lack of statistical significance was observed, probably as a consequence of the small effective size of the subsets available, a common difficulty in the modeling of rare events as is the case of mutations. The amount of data used in the different analyses varied widely, depending on how the data were reported in the publications analyzed. This shows a regrettable waste of produced data, due to inadequate communication of the results, supporting an urgent need of publication guidelines for mutation studies.
- Reverse Body Fluid Identification Workflow: A Direct to DNA ApproachPublication . Porto, Maria-João; Ferreira, Joana; Bento, Ana; Bogas, Vanessa; Lopes, Virgínia; Sampaio, Lisa; Gouveia, Nair; Corte-Real, Francisco; Amorim, António; Amorim, António; Andrade Sampaio, Lisa; Bogas, Vanessa; Ventura Teixeira Bento, Ana Margarida; University of Santiago de Compostela (USC)
- Reverse body fluid identification workflow: a direct to DNA ApproachPublication . Porto, Maria João; Ferreira, Joana; Bento, Ana Margarida; Bogas, Vanessa; Lopes, Virginia; Sampaio, Lisa; Gouveia, Nair; Corte Real Gonçalves, FranciscoWhen forensic DNA laboratories receive evidence from a crime scene their first task is to check for the presence of biological material, namely blood, semen or saliva; the same principle is applied to clothing or swabs related to victims from sexual assault cases. Examination of the exhibits by naked eye or using a forensic light source is done in order to detect the presence of body fluid stains. Many laboratories perform preliminary tests on items where biological material is potentially present before sending a cutting or swab for extraction and subsequent DNA typing. To identify the presence of body fluids our laboratory has implemented presumptive and/or confirmatory assays to detect semen, blood and saliva and, until the end of 2022, all samples selected for DNA extraction and posterior amplification were also tested to determine the type of biological evidence in question (whenever enough sample was available) in two independent workflows. For semen identification, all presumptive positive results were then tested in order to visualize sperm cells. However, in sexual assault cases there are many samples with a semen presumptive positive result but with a negative confirmatory test, meaning that this biological fluid cannot be confirmed. On the other hand, it was detected that in several situations the analysed samples did not present probative DNA results and, consequently, it would not have been necessary to test them for the presence of bodily fluids. The aim of this study was to propose a more efficient workflow to be applied to all forensic samples 647 samples from sexual assault crimes (male/female victims), occurred between 2020 and 2021, were selected and the results obtained in both previously mentioned workflows were evaluated and compared with a Direct to DNA approach, in which DNA analysis is performed prior to body fluids identification (carried out only on samples with eligible DNA profiles for the criminal case under study). The results revealed that if a Direct to DNA approach was adopted, only 256 samples (39,6%) would have been tested for the presence of semen (confirmed in 80 samples). Therefore, this workflow (currently implemented in our laboratory) is less laborious and time-consuming, allows standardization of the techniques implemented and, above all, no loss of information relevant to the judicial process was detected