F. Balsa

National Institute of Legal Medicine, Coímbra, Coimbra, Portugal

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Publications (35)12.71 Total impact

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    ABSTRACT: Abstract This work aimed to study the rapidly mutating Y-STRs in a population of Portugal Centre. The results showed that these markers are highly polymorphic, observing that each sample had a unique haplotype.
    Forensic Science International Genetics Supplement Series 12/2013; DOI:10.1016/j.fsigss.2013.10.042
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    ABSTRACT: Samples analysed in this study suffered from afflictions, such as low level DNA, degradation and PCR inhibitors: samples with induced degraded conditions and real crime scene samples, from a wide range of crimes.Results obtained with NGM SElect™ PCR amplification kit and PowerPlex® ESI 17 system were compared, to verify the behaviour of both kits in the presence of challenging samples.
    Forensic Science International Genetics Supplement Series 12/2011; 3(1-1):e123 - e124. DOI:10.1016/j.fsigss.2011.08.061
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    ABSTRACT: A variety of challenging biological samples, including blood stains, saliva, semen, hair, bones, finger nails, among others, are often a part of our casework investigation. In this study, semen, blood samples and saliva swabs were extracted by several methods in order to optimize and validate the Prepfiler Express™ Extraction kit and the AutoMate Express DNA Extraction System. Results obtained with the robot (using silica-coated magnetic beads) were compared with methods based on a chelating resin, silica membranes and paramagnetic resin.
    Forensic Science International Genetics Supplement Series 12/2011; 3(1):e377 - e378. DOI:10.1016/j.fsigss.2011.09.050
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    ABSTRACT: Samples of 70 individuals from 3 ethnic groups from Angola (Bakongos, Kimbundu and Ovimbundu) were studied analysing the polymorphisms of the entire mitochondrial control region in order to verify the genetic diversity. A total of 68 different haplotypes were identified, 66 being unique. Sequence diversity was estimated to be 1.0000. ±. 0.0113 and nucleotide diversity for Bakongo, Kimbundu and Ovimbundu ethnic groups were 0.015556. ±. 0.007970, 0.016772. ±. 0.008517 and 0.016020. ±. 0.008411, respectively. It was possible to include the majority of the mtDNA haplotypes into a specific African mtDNA haplogroup.
    Forensic Science International Genetics Supplement Series 12/2011; 3(1). DOI:10.1016/j.fsigss.2011.08.062
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    ABSTRACT: AmpFlSTR® NGM™ is a 16-locus multiplex kit claiming improved robustness than earlier generation AppliedBiosystems kits; NGM-SElect™ was released recently as an equivalent to NGM loci plus SE33 so it was determined if NGM-SElect can be an asset compared to NGM in low-level DNA samples.
    Forensic Science International Genetics Supplement Series 12/2011; 3(1-1):e121 - e122. DOI:10.1016/j.fsigss.2011.08.060
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    ABSTRACT: The aim of the present work was to study the origin of paternal lineages in Angola population, namely in the three main ethnic groups, inferred by phylogeographic analyses of Y chromosome defined haplogroups. To determine the male lineages present in the Angola population studied, 112 unrelated males were typed using a PCR multiplex – minisequencing SnaPshot based method including 29Y-SNPs, which characterize the majority haplogroups in sub-Saharan Africa populations.
    Forensic Science International Genetics Supplement Series 12/2011; 3:e369-e370. DOI:10.1016/j.fsigss.2011.09.046
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    ABSTRACT: Challenging biological samples found in crime scenes are often brought to our lab. Several factors, such as degradation and the presence of inhibitors, can difficult the analysis of these samples. Chelating resin, silica membranes, silica-coated magnetic beads and paramagnetic resin were DNA extraction techniques used in this study. Our aim was to find out the DNA extraction method more suitable to overcome problems raised by these samples and to enable the identification of its genetic profile.
    Forensic Science International Genetics Supplement Series 12/2011; 3(1). DOI:10.1016/j.fsigss.2011.08.097
  • Forensic Science International Genetics Supplement Series 12/2011; 3(1). DOI:10.1016/j.fsigss.2011.08.066
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    ABSTRACT: The AmpFlSTR® Identifiler® Direct PCR Amplification Kit is a short tandem repeat (STR) multiplex assay, optimized to amplify 16 loci directly from biological material (blood or buccal cell samples) stored in FTA paper, without resorting to DNA extraction. However, preliminary experiences have shown the versatility and robustness of this amplification kit, when applied to other biological sample supports. The aim of this research work is to analyze the results of this kit when applied to non-FTA paper or other support for biological samples such as a buccal swab.
    Forensic Science International Genetics Supplement Series 12/2011; 3(1-1):e371 - e372. DOI:10.1016/j.fsigss.2011.09.047
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    ABSTRACT: The aim of the present work was to study the origin of paternal and maternal lineages in Guinea-Bissau population, inferred by phylogeographic analyses of mtDNA and Y chromosome defined haplogroups. To determine the male lineages present in Guinea-Bissau, 33 unrelated males were typed using a PCR-SNaPshot multiplex based method including 24 Y-SNPs, which characterize the main haplogroups in sub-Saharan Africa and Western Europe. In the same samples, 17 Y-STRs (included in the YFiler kit, Applied Biosystems) were additionally typed. The most frequent lineages observed were E1b1a (xE1b1a4,7)-M2 (68%) and E1a-M33 (15%). The European haplogroup R1b1-P25 was represented with a frequency of 12%. The two hypervariable mtDNA regions were sequenced in 79 unrelated individuals from Guinea-Bissau, and haplogroups were classified based on control region motifs using mtDNA manager. A high diversity of haplogroups was determined in our sample being the most frequent haplogroups characteristic of populations from sub-Saharan Africa, namely L2a1 (15%), L3d (13%), L2c (9%), L3e4 (9%), L0a1 (8%), L1b (6%) and L1c1 (6%). None of the typical European haplogroups (H, J and T) were found in the present sample of Guinea-Bissau. From our results, it is possible to confirm that Guinea-Bissau presents a typically West African profile, marked by a high frequency of the Y chromosome haplogroup E1b1a(xE1b1a4,7)-M2 and a high proportion of mtDNA lineages belonging to the sub-Saharan specific sub-clusters L1 to L3 (89%). A small European influx has been also detected, although restricted to the male lineages.
    Forensic Science International: Genetics 11/2010; 5(2):114-6. DOI:10.1016/j.fsigen.2010.10.007 · 3.20 Impact Factor
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    ABSTRACT: Mitochondrial DNA analysis is very useful for the interpretation of the history of human migration and to estimate the frequency of a haplotype in the forensic context. From a human settlement perspective, La Paz area is greatly interesting since the first planned city of the region is located there. Samples from 110 individuals from La Paz were studied analyzing the polymorphisms in the D-loop, hypervariable region I (HVI) and hypervariable region II (HVII) in order to verify the genetic diversity. The aim of this study was to start the creation of a population database in order to obtain the genetic interpopulation variability and classify haplotypes into characteristic haplogroups of South America. A total of 97 different haplotypes were identified, 90 being unique, expressed by 122 polymorphic nucleotide positions. Nucleotide and sequence diversity were estimated to be 0.015 _ 0.0075 and 0.996, respectively. Haplogroup distribution in the samples was 57.27% B4, 19.09% C1, 10.00% A2, 3.64% D1, 2.73% D4h3, 1.82% H, and 0.91% for each of the haplogroups A4, B4c1a, CZ, D4J, M7a and M8/N9b. The rate of length heteroplasmy was 36.36% in HVI and 52.73% in HVII. Phylogenetic analysis reveals proximity to the Korean, Chilean aboriginal, Japanese and Australian populations. The estimated genetic variability of the studied population was high, suggesting an early settlement.
    Journal of Forensic and Legal Medicine 07/2010; 17:247e253. DOI:10.1016/j.jflm.2010.02.011 · 0.99 Impact Factor
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    ABSTRACT: Pets live with people and place biological samples everywhere, which may be useful in a forensic context linking suspects and victims, to an occurrence.The genetic diversity of canine microsatellite loci PEZ1, FHC2054, FHC2010, PEZ5, PEZ20, PEZ12, PEZ3, PEZ6, PEZ8 and FHC2079 was investigated in a population of 63 Portuguese dogs.Preliminary results show that the studied markers appeared to be polymorphic, thus contributing to increase the potential of forensic samples of animal origin. The number of alleles per locus, varied between five (FHC2010) to 20 (PEZ3) and allelic frequencies were estimated.
    Forensic Science International Genetics Supplement Series 12/2009; 2(1):288-289. DOI:10.1016/j.fsigss.2009.08.068
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    ABSTRACT: This study analyzes the allelic frequency distribution of 17 STRs contained in the AmpFlSTR Identifiler (Applied Biosystems) and PowerPlex16 System (Promega) commercial kits for two large population samples from the Azores archipelago (Portugal) (N=475) and from Central Portugal (N=2125). Likewise, it includes a comparative study among the population groups analyzed in this paper and those which history points out as originating from the first settlers of the Azores. All loci were highly polymorphic. The Central Portuguese area and the Azores archipelago population samples are in Hardy-Weinberg equilibrium for the 17 markers analyzed.
    Forensic Science International: Genetics 12/2009; 4(1):e1-7. DOI:10.1016/j.fsigen.2008.12.001 · 3.20 Impact Factor
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    ABSTRACT: Mitochondrial DNA (mtDNA) has enormous potential in forensic genetics, allowing identification of genetic material from degraded samples. Genetic testing can also be performed using mtDNA coding region SNPs. SNPs have a number of characteristics that make them unique for forensic analysis, allowing the successful analysis of degraded samples. The aim of the present study was to evaluate the effectiveness of a mtSNP typing assay on skeletal remains that were buried directly in soil for more than thirty years in adverse climate conditions.
    Forensic Science International Genetics Supplement Series 12/2009; 2:215-216. DOI:10.1016/j.fsigss.2009.08.075
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    ABSTRACT: Study of mitochondrial DNA (mtDNA) control region is a current practice in forensic genetics. In our service, mtDNA analysis is performed in many evidentiary specimens. Evaluation of this methodology is important to improve quality, increase efficiency and decrease artefacts, in order to reduce costs and time consuming. A case with 12 reference samples (bucal swabs) and 190 telogenic hair specimens extracted with DNA IQ™ System Tissue and Hair Extraction Kit (Promega) is reported. HVS-1 and HVS-2 control regions were sequenced with BigDye® Terminator v1.1 Kit (Applied Biosystems), using BetterBuffer (Microzone Limited), followed by a simple bead purification method (XTerminator) to remove unincorporated terminators. Application of this procedure had success in 180 hair samples within a very short time comparing to dRhodamine/ethanolic precipitation sequencing strategy and also demonstrated that better results are achieved with clean sequence data closer to the primer. The quality of data produced by the BigDye/BetterBuffer/XTerminator (BDX) procedure has been demonstrated to be very high. Besides that the BDX procedure can significantly reduce overall processing time and cost per reaction. This new methodology has additional advantages like fewer reagent transfers and smaller amounts of DNA.
    Forensic Science International Genetics Supplement Series 12/2009; 2:97-98. DOI:10.1016/j.fsigss.2009.08.011
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    ABSTRACT: Degraded human remains and crime scene evidences with small amounts of DNA typically reveal incomplete or null genetic profiles when using standard (large) STR amplicons. The technology of mini-STRs, using reduced-size STR amplicons, can help to recover information from these samples. In our Forensic Genetic Service several genetic profiles were obtained or completed using MiniFiler kit (Applied Biosystems) increasing the success rate in sample typing. In all studied cases no inconsistencies were found between profiles obtained with MiniFiler and Identifiler, suggesting that this mini-STR kit can be used to include low copy number (LCN) evidence profiles in STR databases.
    Forensic Science International Genetics Supplement Series 12/2009; 2(1):121-122. DOI:10.1016/j.fsigss.2009.08.064
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    ABSTRACT: Mitochondrial DNA (mtDNA) has a great potential in forensic and population genetics, allowing the identification of population origin of individuals and related trace samples. In order to apply this methodology as inclusion evidence in forensic practice it is necessary to determine the population genetic structure. Here, we present haplogroup discrimination of a Central Portuguese population using 16 mtSNPs. Haplogroups in the Central Portuguese population were determined with the following distribution: Hg H: 40.19%, Hg V: 4.90%; Hg HV: 4.90%, Hg U: 13.72%, Hg K: 5.88%; Hg T: 10.78%; Hg J: 9.80%, Hg I: 1.96%, Hg X: 2.94% and others: 4.90%, being this distribution in accordance with other European populations.
    Forensic Science International Genetics Supplement Series 12/2009; 2:322-323. DOI:10.1016/j.fsigss.2009.08.093
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    ABSTRACT: A part of a decomposed human body from an individual was found at his home, together with the decomposed bodies of his 3 dogs. The disappearance of half of the human body was hardly explained. Hypothetically the dogs, starving, could have eaten their owner after his death. All the bodies were recovered for autopsy. Small bone fragments were recovered in one dog's stomach and identified as human by anthropological analysis. DNA was extracted and cytochrome b gene analysis was made in order to determine their origin, confirmed as human. Genetic identification allowed achieving an eight mini-STR profile with MiniFiler (Applied Biosystems) identical to the bone material collected at the victim's autopsy, confirmed that the dogs had effectively eaten their owner. The results showed that it is possible to obtain nuclear DNA in samples subjected to gastric acids and the combination of different techniques allowed us to determine, in each step, the most convenient workflow for the remains identification.
    Forensic Science International Genetics Supplement Series 12/2009; 2:210-212. DOI:10.1016/j.fsigss.2009.08.010
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    ABSTRACT: In recent years, an interest has grown with Y-chromosome single nucleotide polymorphisms (Y-SNPs) and their potential applications, especially in evolutionary biology, forensics and medical genetics. A total of 81 samples from unrelated males of the Brazilian population of São Paulo State (Ribeirão Preto) have been analyzed for 14 Y-SNPs (SRY1532, M213, M9, M70, M22, TAT, 92R7, M173, P25—multiplex 1; M170, M62, M172, M26 and M201—multiplex 2) using the SNaPshot™ methodology, and haplogroups frequencies were determined. European influence (mainly due to the male Portuguese settlers, but also the later arrival of Spanish and Italian) is therefore confirmed, given the fact that the most predominant European haplogroup R1b1 is also the most representative haplogroup (53.09%), followed by haplogroup J2 (with not more than 12.35%). The remaining haplogroups have made a minor contribution, between 9.88% and 1.23%, yet very significant.
    Forensic Science International Genetics Supplement Series 12/2009; 2(1):427-428. DOI:10.1016/j.fsigss.2009.08.117
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    ABSTRACT: Mitochondrial DNA analysis is a useful tool for typing evidences with small amounts or no nuclear DNA. A homicide case with several hairs is reported. Hair samples were washed in ethanol (70%) for 30min followed by a further wash step in sterile distilled water for 30min. The sequencing strategy BigDye/BetterBuffer/XTerminator was applied. In the presented case a mixture of both victim/aggressor haplotype was detected in hair samples previously washed.
    Forensic Science International Genetics Supplement Series 12/2009; 2(1):217-218. DOI:10.1016/j.fsigss.2009.08.017