Antonio Salas

Instituto Nacional de Toxicología y Ciencias Forenses, Madrid, Madrid, Spain

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Publications (224)940.91 Total impact

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    ABSTRACT: Guatemala is a multiethnic and multilingual country located in Central America. The main population groups separate 'Ladinos' (mixed Native American-African-Spanish), and Native indigenous people of Maya descent. Among the present-day Guatemalan Maya, there are more than 20 different ethnic groups separated by different languages and cultures. Genetic variation of these communities still remains largely unexplored. The principal aim of this study is to explore the genetic variability of the Maya and 'Ladinos' from Guatemala by means of uniparental and ancestry informative markers (AIMs). Analyses of uniparental genetic markers indicate that Maya have a dominant Native American ancestry (mitochondrial DNA [mtDNA]: 100%; Y-chromosome: 94%). 'Ladino', however, show a clear gender-bias as indicated by the large European ancestry observed in the Y-chromosome (75%) compared to the mtDNA (0%). Autosomal polymorphisms (AIMS) also mirror this marked gender-bias: (i) Native American ancestry: 92% for the Maya vs. 55% for the 'Ladino', and (ii) European ancestry: 8% for the Maya vs. 41% for the 'Ladino'. In addition, the impact of the Trans-Atlantic slave trade on the present-day Guatemalan population is very low (and only occurs in the 'Ladino'; mtDNA: 9%; 4%), in part mirroring the fact that Guatemala has a predominant orientation to the Pacific Ocean instead of a Caribbean one. Sequencing of entire Guatemalan mitogenomes has led to improved Native American phylogeny via the addition of new haplogroups that are mainly observed in Mesoamerica and/or the North of South America. The data reveal the existence of a fluid gene flow in the Mesoamerican area and a predominant unidirectional flow towards South America, most likely occurring during the Pre-Classic (1800 BC-200 AD) and the Classic (200-1000 AD) Eras of the Mesoamerican chronology, coinciding with development of the most distinctive and advanced Mesoamerican civilization, the Maya. Phylogenetic features of mtDNA data also suggest a demographic scenario that is compatible with moderate local endogamy and isolation in the Maya combined with episodes of gene exchange between ethnic groups, suggesting an ethno-genesis in the Guatemalan Maya that is recent and supported on a cultural rather than a biological basis.
    BMC Genomics 12/2015; 16(1):1339. DOI:10.1186/s12864-015-1339-1 · 3.99 Impact Factor
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    ABSTRACT: In 1985, a frozen mummy was found in Cerro Aconcagua (Argentina). Archaeological studies identified the mummy as a seven-year-old Inca sacrifice victim who lived >500 years ago, at the time of the expansion of the Inca Empire towards the southern cone. The sequence of its entire mitogenome was obtained. After querying a large worldwide database of mitogenomes (>28,000) we found that the Inca haplotype belonged to a branch of haplogroup C1b (C1bi) that has not yet been identified in modern Native Americans. The expansion of C1b into the Americas, as estimated using 203 C1b mitogenomes, dates to the initial Paleoindian settlements (~18.3 thousand years ago [kya]); however, its internal variation differs between Mesoamerica and South America. By querying large databases of control region haplotypes (>150,000), we found only a few C1bi members in Peru and Bolivia (e.g. Aymaras), including one haplotype retrieved from ancient DNA of an individual belonging to the Wari Empire (Peruvian Andes). Overall, the results suggest that the profile of the mummy represents a very rare sub-clade that arose 14.3 (5-23.6) kya and could have been more frequent in the past. A Peruvian Inca origin for present-day C1bi haplotypes would satisfy both the genetic and paleo-anthropological findings.
    Scientific Reports 11/2015; 5:16462. DOI:10.1038/srep16462 · 5.58 Impact Factor
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    ABSTRACT: The territory of Chile is particularly long and narrow, which combined with its mountainous terrain, makes it a unique scenario for human genetic studies. We obtained 995 control region mitochondrial DNA (mtDNA) sequences from Chileans representing populations living at different latitudes of the country from the North to the southernmost region. The majority of the mtDNA profiles are of Native American origin (∼88%). The remaining haplotypes are mostly of recent European origin (∼11%), and only a minor proportion is of recent African ancestry (∼1%). While these proportions are relatively uniform across the country, more structured patterns of diversity emerge when examining the variation from a phylogeographic perspective. For instance, haplogroup A2 reaches ∼9% in the North, and its frequency decreases gradually to ∼1% in the southernmost populations, while the frequency of haplogroup D (sub-haplogroups D1 and D4) follows the opposite pattern: 36% in the southernmost region, gradually decreasing to 21% in the North. Furthermore, there are remarkable signatures of founder effects in specific sub-clades of Native American (e.g. haplogroups D1j and D4p) and European (e.g. haplogroups T2b3 and K1a4a1a+195) ancestry. We conclude that the magnitude of the latitudinal differences observed in the patterns of mtDNA variation might be relevant in forensic casework.
    Forensic Science International: Genetics 10/2015; 20:81-88. DOI:10.1016/j.fsigen.2015.10.002 · 4.60 Impact Factor
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    ABSTRACT: There is a large number of applications where family relationships need to be determined from DNA data. In forensic science, competing ideas are in general verbally formulated as the two hypotheses of a test. For the most common paternity case, the null hypothesis states that the alleged father is the true father against the alternative hypothesis that the father is an unrelated man. A likelihood ratio is calculated to summarize the evidence. We propose an alternative framework whereby a model and the hypotheses are formulated in terms of parameters representing identity-by-descent probabilities. There are several advantages to this approach. Firstly, the alternative hypothesis can be completely general. Specifically, the alternative does not need to specify an unrelated man. Secondly, the parametric formulation corresponds to the approach used in most other applications of statistical hypothesis testing and so there is a large theory of classical statistics that can be applied. Theoretical properties of the test statistic under the null hypothesis are studied. An extension to trios of individuals has been carried out. The methods are exemplified using simulations and a real dataset of 27 Spanish Romani individuals.
    Statistical Applications in Genetics and Molecular Biology 10/2015; DOI:10.1515/sagmb-2014-0080 · 1.13 Impact Factor
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    ABSTRACT: Background: Vitamin D is known to have modulatory actions in the immune system. Its influence on the severity of lower tract acute respiratory infections (LT-ARI) is unclear. Objectives: To evaluate the role of vitamin D on LT-ARI in pediatric patients. Methods: Children admitted to hospital with LT-ARI were prospectively recruited through GENDRES-network (March 2009-May 2013). 25-hydroxyvitamin D (25-OHD) levels were measured by immunoassay. The severity of the illness was evaluated according to clinical scales, length of hospital stay (LOS), ventilatory requirements and PICU admission. Results: 347 patients with a median (interquartile range) age of 8.4 (2.6, 21.1) months were included. The mean (SD) 25-OHD levels in our series were 27.1 (11.3) ng/ml. In this study a cutoff value of 30 ng/ml or higher was considered optimal vitamin status. Patients with 25-OHD levels <20 ng/ml were at a higher risk of showing severe signs of respiratory difficulties [OR (95%CI): 5.065 (1.998, 12.842); P-value = 0.001] than patients with normal values, and had a 117% higher risk of oxygen necessity and 217% higher risk of ventilatory requirement than those patients with normal values. An inverse correlation was found between 25-OHD levels and the severity in the evaluated scales. 25-OHD levels did not influence PICU admission rate or LOS. Conclusion: 25-OHD levels of children admitted due to a LT-ARI are below 30 ng/ml. Lower levels of 25-OHD were found to be correlated with severity of the disease. The possible role of abnormal 25-OHD levels as a facilitator or consequence of the infection needs further evaluation.
    Journal of pediatric gastroenterology and nutrition 10/2015; DOI:10.1097/MPG.0000000000001003 · 2.63 Impact Factor
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    ABSTRACT: A study of 23 Y-STRs was conducted in 257 individuals living in urban areas from eight Argentinean provinces. The data were meta-analyzed together with 364 profiles obtained from the literature that represent other five provinces. A total of 255 different haplotypes were observed (253 singletons). Genetic structure estimated from analysis of molecular variance (AMOVA) and exploring different grouping scenarios, yielded high within population variance. Not surprisingly, analyses of genetic distances with respect to main ancestral continental populations indicated Argentinean haplotypes to be closely related to European ones. Overall, these results provide a quite complete picture of the patterns of Y chromosome variation in Argentina, notably contributing to increase the previous national database, and consequently allowing a better estimation of parameters of interest in forensic casework and parentage testing.
    Forensic Science International: Genetics 10/2015; 20:1-5. DOI:10.1016/j.fsigen.2015.09.002 · 4.60 Impact Factor
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    ABSTRACT: Molecular techniques can often reveal a broader range of pathogens in respiratory infections. We aim to investigate the prevalence and age pattern of viral co-infection in children hospitalized with lower tract acute respiratory infection (LT-ARI), using molecular techniques. A nested polymerase chain reaction approach was used to detect Influenza (A, B), metapneumovirus, respiratory syncytial virus (RSV), parainfluenza (1-4), rhinovirus, adenovirus (A-F), bocavirus and coronaviruses (NL63, 229E, OC43) in respiratory samples of children with acute respiratory infection prospectively admitted to any of the GENDRES network hospitals between 2011-2013. The results were corroborated in an independent cohort collected in the UK. A total of 204 and 97 nasopharyngeal samples were collected in the GENDRES and UK cohorts, respectively. In both cohorts, RSV was the most frequent pathogen (52.9% and 36.1% of the cohorts, respectively). Co-infection with multiple viruses was found in 92 samples (45.1%) and 29 samples (29.9%), respectively; this was most frequent in the 12-24 months age group. The most frequently observed co-infection patterns were RSV-Rhinovirus (23 patients, 11.3%, GENDRES cohort) and RSV-bocavirus / bocavirus-influenza (5 patients, 5.2%, UK cohort). The presence of more than one virus in pediatric patients admitted to hospital with LT-ARI is very frequent and seems to peak at 12-24 months of age. The clinical significance of these findings is unclear but should warrant further analysis.
    PLoS ONE 09/2015; 10(9):e0136526. DOI:10.1371/journal.pone.0136526 · 3.23 Impact Factor

  • Journal of Genetics and Genomics 09/2015; DOI:10.1016/j.jgg.2015.09.005 · 3.59 Impact Factor
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    ABSTRACT: During the period of the Transatlantic Slave Trade (TAST) some enslaved Africans were forced to move to Upper Peru (nowadays Bolivia). At first they were sent to Potosí, but later to the tropical Yungas valley where the Spanish colonizers established a so-called "hacienda system" that was based on slave labor, including African-descendants. Due to their isolation, very little attention has been paid so far to 'Afro-Bolivian' communities either within the research field of TAST or in genetic population studies. In this study, a total of 105 individuals from the Yungas were sequenced for their mitochondrial DNA (mtDNA) control region, and mitogenomes were obtained for a selected subset of these samples. We also genotyped 46 Ancestry Informative Markers (AIM) in order to investigate continental ancestry at the autosomal level. In addition, Y-chromosome STR and SNP data for a subset of the same individuals was also available from the literature. The data indicate that the partitioning of mtDNA ancestry in the Yungas differs significantly from that in the rest of the country: 81% Native American, 18% African, and 1% European. Interestingly, the great majority of 'Afro-descendant' mtDNA haplotypes in the Yungas (84%) concentrates in the locality of Tocaña. This high proportion of African ancestry in the Tocaña is also manifested in the Y-chromosome (44%) and in the autosomes (56%). In sharp contrast with previous studies on the TAST, the ancestry of about 1/3 of the 'Afro-Bolivian' mtDNA haplotypes can be traced back to East and South East Africa, which may be at least partially explained by the Arab slave trade connected to the TAST.
    PLoS ONE 08/2015; 10(8):e0134129. DOI:10.1371/journal.pone.0134129 · 3.23 Impact Factor
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    Dataset: nature13673

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    ABSTRACT: The Great Lakes lie within a region of East Africa with very high human genetic diversity, home of many ethno-linguistic groups usually assumed to be the product of a small number of major dispersals. However, our knowledge of these dispersals relies primarily on the inferences of historical, linguistics and oral traditions, with attempts to match up the archaeological evidence where possible. This is an obvious area to which archaeogenetics can contribute, yet Uganda, at the heart of these developments, has not been studied for mitochondrial DNA (mtDNA) variation. Here, we compare mtDNA lineages at this putative genetic crossroads across 409 representatives of the major language groups: Bantu speakers and Eastern and Western Nilotic speakers. We show that Uganda harbours one of the highest mtDNA diversities within and between linguistic groups, with the various groups significantly differentiated from each other. Despite an inferred linguistic origin in South Sudan, the data from the two Nilotic-speaking groups point to a much more complex history, involving not only possible dispersals from Sudan and the Horn but also large-scale assimilation of autochthonous lineages within East Africa and even Uganda itself. The Eastern Nilotic group also carries signals characteristic of West-Central Africa, primarily due to Bantu influence, whereas a much stronger signal in the Western Nilotic group suggests direct West-Central African ancestry. Bantu speakers share lineages with both Nilotic groups, and also harbour East African lineages not found in Western Nilotic speakers, likely due to assimilating indigenous populations since arriving in the region ~3000 years ago.
    Human Genetics 07/2015; 134(9). DOI:10.1007/s00439-015-1583-0 · 4.82 Impact Factor
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    ABSTRACT: We estimated the allele frequencies for the 15 autosomal STR loci included in the AmpFlSTR(®) Identifiler (Applied Biosystems, USA) in a sample of 986 unrelated non-Native American individuals collected at five different localities from Chile, namely, Iquique, Santiago, Concepción, Temuco and Punta Arenas. Frequency distributions and several forensic parameters were estimated at each recruitment site. In addition, analyses were carried out merging the data into five sample locations. No significant statistical differences could be detected between different regions in Chile. These data represent one of the very few studies performed on autosomal STRs in Chile and therefore provide a useful tool for forensic casework carried out in the country. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
    Forensic Science International: Genetics 05/2015; 19. DOI:10.1016/j.fsigen.2015.05.016 · 4.60 Impact Factor
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    ABSTRACT: Rotavirus vaccine might reduce the risk of hospitalization due to childhood seizures (CS). We aimed to identify and assess variations in the incidence of hospitalizations for CS among children <5 years of age before and after rotavirus vaccine introduction. Annual hospitalization rates for any kind of childhood seizures, before and after rotavirus vaccine (RV) introduction in 2007, were calculated using the official surveillance system for hospitalization data. Our study cohort totaled 6,149 children <5 years admitted to the hospital between 2003 and 2013 with any kind of childhood seizures (780.3*+779.0*+333.2*+345*ICD-9-CM code). The annual hospitalization rates for any kind of CS in children <5 years were correlated with RV coverage (r=-0.673, P=0.033) and rotavirus acute gastroenteritis (RAGE) admission rates (ρ=0.506, P=0.001), with decrease rates ranging from 16.2% (95% CI=8.3-23.5%) in 2007 to 34.0% (27.3-40.1%) in 2010, as compared to the median rate of the pre-vaccination period (2003 to 2006). Similarly, for convulsions (780.3*ICD-9-CM code) the decrease seen in children <5 years was significantly correlated with the increase in RV coverage (r=-0.747, P=0.013) and RAG admission rates (ρ=0.543, P<.001), with decrease rates ranging from 18.7% (9.6-26.8%) in 2007 to 42.5% (35.3-48.9%) in 2012. Significant results were also obtained for infants <12 months and infants 1-2 years. In the remaining age groups or diagnostic categories analyzed, changes were either not significant or not related to vaccination changes or RAGE admission rates. Our results show that rotavirus vaccination may have a significant impact in the decrease in seizure-related hospitalizations in childhood. This additional benefit of rotavirus vaccination seems more marked in the youngest infants.
    The Pediatric Infectious Disease Journal 04/2015; 34(7). DOI:10.1097/INF.0000000000000723 · 2.72 Impact Factor
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    ABSTRACT: In most societies, surnames are passed down from fathers to sons, just like the Y chromosome. It follows that, theoretically, men sharing the same surnames would also be expected to share related Y chromosomes. Previous investigations have explored such relationships, but so far, the only detailed studies that have been conducted are on samples from the British Isles. In order to provide additional insights into the correlation between surnames and Y chromosomes, we focused on the Spanish population by analysing Y chromosomes from 2121 male volunteers representing 37 surnames. The results suggest that the degree of coancestry within Spanish surnames is highly dependent on surname frequency, in overall agreement with British but not Irish surname studies. Furthermore, a reanalysis of comparative data for all three populations showed that Irish surnames have much greater and older surname descent clusters than Spanish and British ones, suggesting that Irish surnames may have considerably earlier origins than Spanish or British ones. Overall, despite closer geographical ties between Ireland and Britain, our analysis points to substantial similarities in surname origin and development between Britain and Spain, while possibly hinting at unique demographic or social events shaping Irish surname foundation and development.European Journal of Human Genetics advance online publication, 22 April 2015; doi:10.1038/ejhg.2015.75.
    European journal of human genetics: EJHG 04/2015; DOI:10.1038/ejhg.2015.75 · 4.35 Impact Factor
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    ABSTRACT: Genetic analyses have recently been carried out on present-day Tuscans (Central Italy) in order to investigate their presumable recent Near East ancestry in connection with the long-standing debate on the origins of the Etruscan civilization. We retrieved mitogenomes and genome-wide SNP data from 110 Tuscans analyzed within the context of The 1000 Genome Project. For phylogeographic and evolutionary analysis we made use of a large worldwide database of entire mitogenomes (>26,000) and partial control region sequences (>180,000). Different analyses reveal the presence of typical Near East haplotypes in Tuscans representing isolated members of various mtDNA phylogenetic branches. As a whole, the Near East component in Tuscan mitogenomes can be estimated at about 8%; a proportion that is comparable to previous estimates but significantly lower than admixture estimates obtained from autosomal SNP data (21%). Phylogeographic and evolutionary inter-population comparisons indicate that the main signal of Near Eastern Tuscan mitogenomes comes from Iran. Mitogenomes of recent Near East origin in present-day Tuscans do not show local or regional variation. This points to a demographic scenario that is compatible with a recent arrival of Near Easterners to this region in Italy with no founder events or bottlenecks.
    PLoS ONE 03/2015; 10(3):e0119242. DOI:10.1371/journal.pone.0119242 · 3.23 Impact Factor
  • Antonio Salas · Joanna L Elson ·
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    ABSTRACT: We have set out a short guide to help prevent false positive and negative results in mitochondrial DNA (mtDNA) case-control association studies. Currently the mtDNA association literature is replete with conflicting reports. Associating mtDNA variation with common disease is a complex task, which requires a detailed understanding of the nuances of mitochondrial genetics. We present some of the reasons for the conflicting associations with possible solutions. We feel that this is important, as the continued publication of association studies that fall short of current design criteria will impact negatively on the field.
    Journal of Genetics and Genomics 03/2015; 42(4). DOI:10.1016/j.jgg.2015.03.002 · 3.59 Impact Factor
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    ABSTRACT: Certain mitochondrial DNA (mtDNA) variants and haplogroups have been found to be associated with neurological disorders. Several studies have suggested that mtDNA variation could have an etiologic role in these disorders by affecting the ATP production on high-energy demanding organs, such as the brain. We have analyzed 15 mtDNA SNPs (mtSNPs) in five cohorts of cases presenting Alzheimer disease (AD), Parkinson disease (PD), and migraine, and in controls, to evaluate the role mtDNA variation in disease risk. Association tests were undertaken both for mtSNPs and mitochondrial haplogroups. No significant association was detected for any mtSNP or haplogroup in AD and PD cohorts. Two mtSNPs were associated with one migraine cohort after correcting for multiple tests, namely, T4216C and G13708A and haplogroup J (FDR q-value = 0.02; Santiago's cohort). However, this association was not confirmed in a second replication migraine series. A review of the literature reveals the existence of inconsistent findings and methodological shortcomings affecting a large proportion of mtDNA association studies on AD, PD, and migraine. A detailed inspection of the literature highlights the need for performing more rigorous methodological and statistical standards in mtDNA genetic association studies aimed to avoid false positive results of association between mtDNA variants and neurological diseases. © 2014 Wiley Periodicals, Inc.
    American Journal of Medical Genetics Part B Neuropsychiatric Genetics 01/2015; 168(1). DOI:10.1002/ajmg.b.32276 · 3.42 Impact Factor
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    ABSTRACT: We have analyzed the specific male genetic component of 226 Bolivians recruited in five different regions (“departments”), La Paz, Cochabamba, Pando, Beni, and Santa Cruz. To evaluate the effect of geography on the distribution of genetic variability, the samples were also grouped into three main eco-geographical regions, namely, Andean, Sub-Andean, and Llanos. All the individuals were genotyped for 17 Y-STR and 32 Y-SNP markers. The average Y-chromosome Native American component in Bolivians is 28%, and it is mainly represented by haplogroup Q1a3a, while the average Y-chromosome European ancestry is 65%, and it is mainly represented by haplogroup R1b1-P25. The data indicate that there exists significant population sub-division in the country in terms of continental ancestry. Thus, the partition of ancestries in Llanos, Sub-Andean, and Andean regions is as follows (respectively): (i) Native American ancestry: 47%, 7%, and 19%, (ii) European ancestry: 46%, 86%, and 75%, and (iii) African ancestry: 7%, 7%, and 6%. The population sub-structure in the country is also well mirrored when inferred from an AMOVA analysis, indicating that among-population variance in the country reaches 9.74–11.15%. This suggests the convenience of using regional datasets for forensic applications in Bolivia, instead of using a global and single country database. By comparing the Y-chromosome patterns with those previously reported on the same individuals on autosomal SNPs and mitochondrial DNA (mtDNA), it becomes clear that Bolivians show a strong gender-bias.
    Forensic Science International: Genetics 11/2014; 14. DOI:10.1016/j.fsigen.2014.10.023 · 4.60 Impact Factor
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Publication Stats

7k Citations
940.91 Total Impact Points


  • 2012-2015
    • Instituto Nacional de Toxicología y Ciencias Forenses
      Madrid, Madrid, Spain
  • 2001-2015
    • Instituto De Medicina Legal
      La Habana, La Habana, Cuba
  • 1997-2015
    • University of Santiago de Compostela
      • • Department of Pathological Anatomy and Forensic Sciences
      • • Group of Genomic Medicine
      • • Instituto de Medicina Legal
      Santiago, Galicia, Spain
  • 2011
    • Universität Hamburg
      • Department of Mathematics
      Hamburg, Hamburg, Germany
  • 2010
    • Genome Institute of Singapore
      Tumasik, Singapore
  • 2004
    • University of Huddersfield
      • Department of Chemical and Biological Sciences
      Huddersfield, England, United Kingdom
  • 2002
    • University of Zulia
      • Faculty of Medicine
      Maracaibo, Estado Zulia, Venezuela
  • 1998
    • Complejo Hospitalario Universitario de Santiago
      • Department of Medicine
      Santiago, Galicia, Spain