Vânia Pereira

Analysis of 12 X-STRs in Greenlanders, Danes and Somalis using Argus X-12

X-chromosome markers have become a useful set of markers of choice when certain complex kinship cases need to be unravelled. The Argus X-12 kit allows the co-amplification in a single PCR reaction of 12 X-chromosome short tandem repeats located in four linkage groups. A number of 507 unrelated individuals from Greenland, Denmark and Somalia together with two generation families were typed using the Argus X-12 kit. Silent alleles for the DXS10148 and DXS10146 systems were observed in males, mostly from Somalia. High levels of intrapopulation variability and therefore high forensic parameter values were calculated for the three studied populations. The population in Greenland showed a significantly lower intrapopulation variability and a high genetic differentiation compared with 13 other populations. Significant levels of linkage disequilibrium were observed between markers belonging to the same linkage group, mainly in the populations in Greenland and Somalia. Family studies allowed the calculation of mutation and recombination frequencies. A higher male versus female mutation rate was obtained, with an average value of 3.3 × 10−3. Recombination fraction calculations performed on two generation families showed, as previously described, a not complete independence between X-chromosome linkage groups 3 and 4.

A method for the analysis of 32 X chromosome insertion deletion polymorphisms in a single PCR.

Studies of human genetic variation predominantly use short tandem repeats (STRs) and single nucleotide polymorphisms (SNPs) but Insertion deletion polymorphisms (Indels) are being increasingly explored. They combine desirable characteristics of other genetic markers, especially the possibility of being analysed using short amplicon strategies, which increases the ease of analysis, contributing to justify their interest in population and forensic genetics. After the advent of autosomal and uniparental genomes (mtDNA and Y chromosome), these fields of research are also focusing on the X chromosome, given its special transmission pattern. The X chromosome markers brought new insights into the history of modern human populations and also proved useful in forensic kinship investigations, namely in deficient relationship cases and in cases where autosomes are uninformative. This work describes an X-Indel multiplex system amplifying 32 biallelic markers in one single PCR. The multiplex includes X-Indels shown to be polymorphic in the major human population groups and follows a short amplicon strategy. The set was applied in the genetic characterization of sub-Saharan African, European and East Asian population samples and revealed high forensic efficiency, as measured by the accumulated power of discrimination (0.9999990 was the lowest value in males and 0.999999999998 was the highest in females) and mean exclusion chance varied between 0.998 and 0.9996 in duos and between 0.99997 and 0.999998 in trios. Finally, a segregation analysis was performed using trio constellations of father–mother–daughters in order to address the transmission pattern and assess mutation rates of this type of markers.

Comparative assessment of three cleanup procedures after QuEChERS extraction for determination of trichothecenes (type A and type B) in processed cereal-based baby foods by GC-MS.

A QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method was optimized and validated for the simultaneous extraction of 12 trichothecenes (type A and type B) from baby foods, followed by gas chromatography-mass spectrometry (GC-MS) analysis. Using this methodology, limits of detection and quantification ranging from 0.37 to 19.19 μg/kg and 1.24 to 63.33 μg/kg, respectively, were achieved. Mean recoveries between 44% and 135% were obtained and repeatability, expressed as relative standard deviation, was always lower than 29%. A comparison between the developed method and two alternative cleanup procedures (MultiSep and IAC--immunoaffinity columns) was performed, being the advantages and drawbacks of each one presented. The screening of nine commercially available cereal-based baby foods revealed the presence of 4 out of 12 studied trichothecenes: DON (deoxynivalenol), 15AcDON (15-acetyl-deoxynivalenol), T2-Tetrol and NEO (Neosolaniol). DON was the most commonly found, being detected in 4 samples in significant levels (29-270 μg/kg), sometimes exceeding the maximum permitted level. 15AcDON, T2-Tetrol and NEO were found only in one sample each.

The Karimojong from Uganda: Genetic characterization using an X-STR decaplex system

The Karimojong, an African group from the Karamoja region of Northeast Uganda, were genetically analysed using a decaplex system for X chromosome short tandem repeats (X-STRs). A total of 255 individuals (117 males and 138 females) were genotyped for the following loci: DXS8378, DXS9898, DXS7133, GATA31E08, GATA172D05, DXS7423, DXS6809, DXS7132, DXS9902 and DXS6789. Allele frequencies and parameters for forensic evaluation were calculated for each STR. No association was found between any pairs of loci studied. DXS6789 was the most polymorphic marker in this sample, followed by DXS6809, with gene diversities of 84.79% and 83.94%, respectively. The less discriminating locus observed was DXS7133, with a gene diversity of 39.79%. High overall values of power of discrimination were obtained for female (1 in 1.8 x 10(10)) and male samples (1 in 1.6 x 10(6)), as well as high power of exclusion in father/mother/daughter trios (99.9997%), in father daughter duos (99.9862%) and in half sisters with same father (99.0331%). These results confirm the potential of this 10-plex in parentage testing and in human identification.

A new autosomal STR nineplex for canine identification and parentage testing.

A single multiplex PCR assay capable of simultaneously amplifying nine canine‐specific autosomal STR markers (FH3210, FH3241, FH2004, FH2658, FH4012, REN214L11, FH2010, FH2361 and the newly described C38) was developed for individual identification and parentage testing in domestic dogs. In order to increase genotyping efficiency, amplicon sizes were optimized for a 90–350 bp range, with fluorescently labelled primers for use in Applied Biosystems, Inc., platforms. The performance of this new multiplex system was tested in 113 individuals from a case‐study population and 12 random dogs from mixed‐breed origin. Co‐dominant inheritance of STR alleles was investigated in 101 father, mother and son trios. Expected heterozygosity values vary between 0.5648 for REN214L11 and 0.9050 for C38. The high level of genetic diversity observed for most markers provides this multiplex with a very high discriminating power (matching probability=1.63/1010 and matching probability among siblings=4.9/103). Allele sequences and a proposal for standardized nomenclature are also herein presented, aiming at implementing the use of this system in forensic DNA typing and population genetic studies. This approach resulted in an optimized and well‐characterized canine DNA genotyping system that is highly performing and straightforward to integrate and employ routinely. Although this STR multiplex was developed for use and tested in a case‐study population, the Portuguese breed Cão de Gado Transmontano, it proved to be useful for general identification purposes or parentage testing.

Study of 25 X-chromosome SNPs in the Portuguese

The importance of X-chromosome markers in individual identifications, population genetics, forensics and kinship testing is getting wide recognition. In this work, we studied the distributions of 25 X-chromosome single nucleotide polymorphisms (X-SNPs) in population samples from Northern, Central and Southern Portugal (n=305). The data were also compared with previous data from the Mediterranean area confirming a general genetic homogeneity among populations in the region. The X-SNP distribution in the three Portuguese regional samples did not show any significant substructure and the X-SNP distributions did not differ significantly from those of the majority of Mediterranean populations.

Genetic characterization of uniparental lineages in populations from Southwest Iberia with past malaria endemicity

Malaria endemicity in Southwest Iberia afforded conditions for an increase of sickle cell disease (SCD), which in the region follows a clinal pattern toward the south, where foci of high prevalence were found. SCD distribution is associated with specific geographical areas, and therefore, its introduction into Iberia may be related to the migration of different populations. We have analyzed the variation of uniparental markers in Portuguese populations with high frequency of SCD—Coruche, Pias, and Alcacer do Sal—to evaluate if their present‐day pattern of neutral diversity could provide evidence about people inhabiting the area over different time periods. Two hundred and eighty‐five individuals were sampled in Coruche, Pias, and Alcacer do Sal. All were analyzed for the control region of mitochondrial DNA (mtDNA); males were additionally examined for Y‐chromosome markers. Results were then compared with data from other Portuguese and non‐Portuguese populations. In Coruche, the genetic profile was similar to the profile usually found in Portugal. In Alcacer do Sal, the frequency of sub‐Saharan mtDNA L lineages was the highest ever reported (22%) in Europe. In Pias, mtDNA diversity revealed higher frequencies of Mediterranean haplogroups I, J, and T than usually found in surrounding populations. The presence of Sub‐Saharan maternal lineages in Alcacer do Sal is likely associated with the influx of African slaves between the 15th and 19th centuries, whereas in Pias, the Mediterranean influence might be traced to ancient contacts with Greeks, Phoenicians, and Carthaginians, who established important trading networks in southern Iberia. Am. J. Hum. Biol. 22:588–595, 2010.

NGMSElect™ and Investigator(®) Argus X-12 analysis in population samples from Albania, Iraq, Lithuania, Slovenia, and Turkey.

The analysis of STRs is the main tool when studying genetic diversity in populations or when addressing individual identification in forensic casework. Population data are needed to establish reference databases that can be used in the forensic context. To that end, this work investigated five population samples from Albania, Iraq, Lithuania, Slovenia, and Turkey. Individuals were typed for 16 autosomal STRs and 12 X-chromosomal STRs using the NGMSElect™ and Investigator(®) Argus X-12 kits, respectively. The aim of the study was to characterize the diversity of both STR kits in these population samples and to expand our forensic database. The results showed that all markers were polymorphic in the five populations studied. No haplotype was shared between the males analysed for X-STRs. No statistically significant deviations from Hardy-Weinberg equilibrium were observed for any of the genetic markers included in both the kits. Pairwise LD was only detected in X-STRs between markers located in the same linkage group. Power of discrimination values for males and females and the probability of exclusion in duos and trios were high for the populations in this study.

Population and forensic data for three sets of forensic genetic markers in four ethnic groups from Iran: Persians, Lurs, Kurds and Azeris.

A total of 255 individuals (Persians, Lurs, Kurds and Azeris) from Iran were typed for three sets of forensic genetic markers with the NGM SElect™, DIPplex(®) and Argus X-12 kits. Statistically significant deviations (P≤0.002) from Hardy-Weinberg expectations were observed for the insertion-deletion markers HLD97 and HLD93 after Holm-Šidák correction. Statistically significant (P<0.05) levels of linkage disequilibrium were observed between markers within two of the four studied X-chromosomal linkage groups. AMOVA analyses of the three sets of markers did not show population structure when the individuals were grouped according to their ethnic group. The Iranian population grouped closely to populations living geographically near to Iran based on pairwise FST distances. The matching probabilities ranged from 1 in 3.2×10(7) males by using haplotype frequencies of four X-chromosomal haplogroups to 1 in 3.4×10(21) individuals for the 16 autosomal STRs.

Mirandese language and genetic differentiation in Iberia: a study using X chromosome markers

Abstract Background: In the Iberian Peninsula, the Mirandese dialect, spoken in Miranda do Douro (Portugal) close to the north-eastern border with Spain, has attracted much attention. Aim, subjects and methods: This study focuses on providing further insight into the connections forged between Miranda do Douro and regions in the nearby Province of Zamora. This is in order to better assess the extent to which such relations could have been detained by the current patterns of genetic diversity of the populations, whilst contributing to refining the knowledge on patterns of micro-differentiation within the Peninsula. The genetic characterization of both populations was performed through the analysis of X-chromosomal markers: X-STRs and X-indels. Results and conclusion: The results showed that Miranda do Douro tended to present slightly lower levels of diversity in comparison to the other studied regions, which can be a discreet sign of isolation of that population over the years that might have led the way to the preservation of a language not spoken anywhere else in the country. The analysis of X-STRs particularly brought to light the presence of a subtle population sub-structure at the micro-geographical area encompassing the north-eastern border, which seems to portray the importance of the political border as a mechanism withholding gene flow between the two countries.