T. Ribeiro

National Institute of Legal Medicine, Coímbra, Coimbra, Portugal

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Publications (26)12.21 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Allele frequencies and other relevant forensic parameters for 15 loci studied with AmpFlSTR(R) NGM™ kit were calculated in a population of individuals residing in the south of Portugal. Blood stain samples were obtained from a total of 452 unrelated individuals involved in paternity testing casework. The kit has five loci - D10S1248, D22S1045, D2S441, D1S1656 and D12S391 not present in any other kit used in our laboratory (Powerplex 16 System and Identifiler Plus). In our laboratory, this new kit is used as a screening tool to solve deficient cases as fatherless paternity test, and to help in paternity investigations with only one genetic incompatibility after the use of routine seventeen loci. Furthermore, this five loci included in the European Standard Set are also recommended by the European Network of Forensic Science Institutes "ENFSI" and the European DNA Profiling group "EDNAP". These studies are necessary to calculate statistical forensic parameters such as power of discrimination, power of exclusion, minimum allele frequency. Statistical parameters such as heterozigoty, homozigoty and combined power of exclusion were determinated. This kind of study is part of the Quality Program for Certificated Forensic Laboratories.
    Forensic Science International: Genetics 11/2012; · 3.86 Impact Factor
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    ABSTRACT: Complex kinship analyses are normally a challenge for forensic laboratories, especially in cases in which the individuals involved can have criminal responsibilities. This paper presents two complex relationship caseworks studied with routine STRs and autosomal SNPs as supplementary markers. In the first case, to exclude trafficking of children, maternity investigation of a child was requested involving two alleged mothers – a 39-year-old woman, the alleged grandmother, and her absent daughter. The second one was a possible incest case with a young girl with Trisomy 21 where her father was also the alleged child's father. The individuals of these cases were typed for 17 autosomal STRs with AmpFlSTR Identifiler or IdentifilerPlus and Powerplex 16. Twenty autosomal SNPs were also typed using SNaPshot® methodology, with two 10-plex previously revealed useful in paternity testing. Both cases gave low likelihood ratio values with STRs and a genetic incompatibility was also detected in the first case. SNP studies strongly indicated that the alleged grandmother was not the child's mother but indeed the grandmother in a real complex immigrant kinship case, while in the second casework reinforced the incest relationship. Therefore, SNPs revealed useful as additional markers in complex kinship testing.
    Forensic Science International Supplement Series 01/2011; 3((1)):379-380.
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    ABSTRACT: Single Nucleotide Polymorphisms (SNPs) are having an increasingly role in Forensic Genetics due to very low SNP mutation rates and the possibility to multiplex a great number of loci. The purpose of this study was to evaluate the use of 20 autosomal SNPs as additional markers in the resolution of kinship casework where the alleged father was not available for testing and close relatives were used instead. A total of six caseworks which included alleged paternal grandparents, alleged uncles or alleged brothers were studied. All individuals studied in these cases were typed before with 17 autosomal STRs using Identifiler(Plus)® and Powerplex 16® systems. Twenty SNPs were typed using SNaPshot® methodology with two 10-plex, previously shown useful in paternity testing. LRs were calculated with “Familias” using South Portugal STR and SNP frequency databases. This study confirms that even as few as 20 autosomal SNP loci can be very useful in kinship analysis as a complement to standard methodologies. Moreover, SNaPshot® methodology can be easily implemented in any Forensic Laboratory.
    Forensic Sci Int: Gen. Supplement. 01/2011; 3((1)):508-509.
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    ABSTRACT: Y-STR mutational rate estimation is very important for the correct evaluation of typing results in forensic casework and specially kinship genetic studies. In this work we studied 95 Southern Portuguese Caucasian father/son pairs in order to estimate mutational rates for the 17 Y-STRs multiplex used in routine casework. In a total of 1615 allele transfers three single step mutations were detected in DYS385a, DYS439, and DYS448, with an estimated mutation rate of 10,526 × 10−3 (95%CI 0.265 × 10−3 to 20.788 × 10−3). The estimated average mutation rate is 1.858 × 10−3 (95%CI 8.08 × 10−4 to 2.908 × 10−3). It would be important to characterize more father/son pairs in order to estimate more reliable allele specific mutation rates for the most widely used Y-STRs markers in forensic genetics.
    Forensic Science International Genetics Supplement Series 01/2009; 2(1):60-61.
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    ABSTRACT: Based on the 52 SNP-plex developed by the SNPforID Consortium, we designed two 10-plex to study single nucleotide polymorphisms (SNPs) for human identification and to establish its usefulness in paternity casework. This 20 autosomal SNP set was studied in 56 paternity investigation cases from South Portuguese resident population, also analyzed with 17 Short Tandem Repeats (STRs). Results obtained with both methodologies were consistent with each other, except for one case where the alleged father could not be excluded by SNPs. No mutation was found in the SNP loci, whereas a mismatch in STRs was detected. The use of SNPs as a complement to the analysis of autosomal STRs in paternity casework can result in paternity index and paternity probability values equivalent or higher than those obtained with more STR loci, but with lower costs. This study shows that instead of using additional STR loci, the analysis of 20 autosomal SNPs, as a complement technique to standard methodologies, is an appealing alternative in paternity investigation cases.
    Forensic Science International Genetics Supplement Series 01/2009; 2(1):127-128.
  • Paulo Dario, Joana Bom, Teresa Ribeiro, Helena Geada
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    ABSTRACT: Analysis of control mitochondrial DNA (mtDNA) hypervariable regions is sometimes the only available method to study hair evidence in forensic casework although being a laborious technique. Nowadays there is a huge interest in new genetic markers such as single nucleotide polymorphisms (SNPs) to type degraded forensic samples. For that purpose, a 10-Plex mitochondrial SNP for haplogroup typing, chosen from several SNP studies and useful to study the most common populations in our laboratory was applied in forensic casework. Hair shafts from three forensic cases with different ethnic backgrounds were studied with mtDNA sequencing and compared with mitochondrial SNPs (mtSNPs) study. Coding mtSNP typing prior to sequencing can allow for a rapid screening in forensic casework, which is emphasized in the first two cases. Moreover, in cases in which mtDNA sequencing fails, mtSNPs can still be detected. This 10 SNP loci multiplex provides a less expensive and simpler method for mitochondrial typing compared to control region mtDNA sequencing, especially when used as a fast screening method.
    Forensic Science International Genetics Supplement Series 01/2009; 2(1):187-188.
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    ABSTRACT: A five Mini-SGM multiplex which encompasses TH01, FGA, D18S51, D16S539 and D2S1338, common STR markers in human identity testing, have been performed. Two cases with different biological tissues were selected to illustrate the usefulness of this technique in forensic casework. The use of routine methodology can sometimes give only a partial genetic profile or no profile at all. However, using the Mini-STR technique, a full profile was obtained for the majority of the degraded samples. We conclude that the Mini-SGM methodology is more sensible than routine methodology for degraded samples, although a full genetic profile is not obtained in all cases as results are still very much sample-dependent. This Mini-SGM multiplex can be considered a useful tool to complement conventional STR analysis in degraded samples.
    Forensic Science International Genetics Supplement Series 01/2008; 1(1):100-101.
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    ABSTRACT: The second most studied population in our laboratory comes from Cabo Verde archipelago. In order to use STR data properly we studied 13 codis loci, plus D2S1338, D19S433, PENTA E and PENTA D, from 295 unrelated healthy individuals. Forensic parameters demonstrate that these 17 STR loci are highly discriminative in this population for both paternity testing and routine forensic casework. A 17 STR loci population database from the most frequent African population in our laboratory was established for forensic casework.
    Forensic Science International Genetics Supplement Series 01/2008; 1(1):380-382.
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    ABSTRACT: A new commercial kit, Mentype1 Argus X-8, which analyzes eight X-chromosomal STR markers – DXS7132, DXS7423, DXS8378, DXS10074, DXS10101, DXS10134, DXS10135 and HPRTB, was used. A hundred and one South Portuguese Caucasian individuals and 60 paternity investigation cases, previously performed with routine STRs markers, were studied. Allele frequencies were estimated for the eight XSTRs. More than five exclusions between the alleged father and the female child were observed in almost all exclusion cases, especially in DXS10101, DXS10134 and DXS10135 loci. This set of eight X-chromosomal STRs appears to be quite useful for father–daughter studies and in some kinship investigations.
    Forensic Science International. 01/2008; 1:522–524.
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    ABSTRACT: Ten of the most polymorphic autosomal single nucleotide polymorphisms (SNPs) (∼50% heterozygosity) in European populations, especially NW Spain, selected from a 52 SNP panel for human identification reported by Sanchez et al. [J.J. Sanchez et al., A multiplex assay with 52 single nucleotide polymorphisms for human identification, Electrophoresis, 27 (2006), 1713–1724] were amplified in one PCR reaction followed by detection by single base extension reaction with SNaPshot® multiplex kit. A total of 80 individuals from a South Portuguese population were typed and allele SNP frequencies were estimated which are in agreement with published population genetic studies. More than 20 paternity investigation cases, already performed routinely with STRs, were also studied. In exclusion cases, one, two or three exclusions, mainly in A08 and A12, have been detected. Even performing few SNP loci, but selecting SNPs with allele frequencies near 0.5, the SNP methodology can also be a useful tool in paternity investigation.
    Forensic Science International Genetics Supplement Series 01/2008; 1(1):507-509.
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    ABSTRACT: The most common European lineage (haplogroup H) represents more than 50% of a South Portuguese population sample, which can be poorly discriminative in forensic casework. To detect haplogroup H sub-lineages, seven mitochondrial DNA coding-region SNPs have been studied—3010, 3915, 3992, 4336, 4769, 4793 and 6776, using minisequencing methodology. In our population, seven haplogroup H sub-lineages were obtained, although the paraphyletic cluster H* still predominates. The most frequent sub-lineages were H1 (3010A) and H3 (6776C), in agreement with other Portuguese and Spanish population studies. H7 (4793G) haplogroup was also detected in our study, being rare in some populations. SNaPshot® methodology provides a simple, rapid and informative method to sub-type haplogroup H for forensic casework.
    Forensic Science International Genetics Supplement Series 01/2008; 1(1):285-286.
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    ABSTRACT: Allele frequencies and forensic efficiency parameters for SE33 locus were calculated from a sample of 328 individuals residing in the south of Portugal. A significant deviation from Hardy–Weinberg equilibrium was observed. The results demonstrate the usefulness of SE33 for forensic identification, which should be added to the set of STRs loci routinely studied, namely in complex cases that involve relatives.
    International Congress Series. 01/2006;
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    ABSTRACT: It was necessary to establish a statistically significant population database from South Portugal residents for further reliable statistical analysis in forensic cases. Genetic analysis of 17 loci was performed on samples obtained from 2723 south Portugal residents after informed consent. Allele frequencies and statistical parameters were calculated for each locus.
    International Congress Series 01/2006; 1288:367-368.
  • M. R. Silva, S. Serra, T. Ribeiro, H. Geada
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    ABSTRACT: In Forensic Genetics, it is important that SNP markers have only one polymorphic site for result interpretation, but P25 and 92R7, two of the most widely used Y-SNPs for population studies and forensic purposes, can present two signals. These two loci are Paralogous Sequence Variants. Different polymorphisms detected at P25 and 92R7 loci when performing population studies are reported.
    International Congress Series 01/2006; 1288:19-21.
  • A. Sucena, T. Ribeiro, H. Geada
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    ABSTRACT: The variability in np16184–16193 HVI region presents two different types of polymorphism: sequence variability and length variability with length heteroplasmy. It is important to define properly the HVI homopolimeric regions for a correct classification of homopolimeric track defining the number of As and Cs and the various population types identified by adjacent bases to the homopolimeric track.
    International Congress Series 01/2006; 1288:843-845.
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    ABSTRACT: Degraded samples were studied in order to obtain Y-STR haplotype to provide additional data in paternal lineage identification caseworks. Multiplex reactions were used comprising the minimal Y-STR haplotype DYS19, DYS390, DYS391, DYS392, DYS393, DYS19, DYS389I/II and DYS385 belonging to the Y-STR database. The other Y-STR loci—GATA A 7.1, GATA A 7.2, GATA C4, GATA H4, DYS437, DYS438 and DYS439—were included in the Y-Chromosome Quality Control Group of the Spanish and Portuguese Group (GEPY) of the ISFG. Y-STRs results were successful in almost all the samples when applied some modifications in amplification methods.
    International Congress Series 01/2004; 1261:251-253.
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    ABSTRACT: More than 100 vWA alleles were sequenced to detect any possible sequence difference at this locus in Portuguese Caucasian and African populations. Internal variability was detected—the most common structure is TCTA (TCTG)4 (TCTA)n with a TCTA(TCTG)3(TCTA)n structure more frequent in small alleles and a TCTA (TCTG)5–6 (TCTA)n structure predominantly in large ones. Allele 17 has a unique structure in all 20 studied samples and the nonconsensus allele 14 structure has a prevalence of 60% in both populations. Performing more than 3000 paternity investigation cases with multiplex systems, eight vWA mutations were detected with a 0.0024 average mutation rate. Six mutations at the primer-binding site have also been detected when performing ProfilerPlus/SGMPlus versus Powerplex1.2.
    International Congress Series 01/2004; 1261:248-250.
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    ABSTRACT: This report presents an homicide case which occurred in an African country, involving five Portuguese citizens whose identification was suspected to have been exchanged. HVI and HVII control regions of mtDNA analysis was performed from bones from each of the five corpses in order to achieve identification by comparison with four alleged mothers. Two bodies shared the same sequence, which suggest a kinship relation. Results have confirmed the suspicion of body remains exchange.
    International Congress Series 01/2004; 1261:374-376.
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    ABSTRACT: The aim of this study was to present a Portuguese Population Database of 214 Southern Portugal samples studied with 16 Y-STR loci including the eight minimal Y-STR haplotype—DYS19, DYS390, DYS391, DYS392, DYS393, DYS389I/II, DYS385 and other Y-STR loci—GATA A7.1 (DYS460), GATA C4, GATA A7.2 (DYS461), GATA A10, GATA H4, DYS437, DYS438 and DYS439. In this study, 209 different haplotypes could be defined and 205 haplotypes were found just once. This database has a discrimination power of 97.7%, a haplotype diversity of 99.6% and 2.3% of shared haplotypes. Some samples do not match any sample in the Y-STR Haplotype Reference Database which assigned specific region characteristics to these population samples. Forty-three alleged father–child non-exclusion cases were also studied and two possible mutations have been detected in DYS439 and DYS393. Complex paternity investigation cases without alleged father have also been studied. In an autosomal STR exclusion case, the same 16 Y-STR haplotype was obtained between the excluded alleged father and the child.
    International Congress Series 01/2004; 1261:319-321.
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    Journal of Forensic Sciences 02/2003; 48(1):202-3. · 1.24 Impact Factor