Analysis of 26 STR loci (PowerPlex® Fusion 6C System) in a mestizo population from Mexico city.

BACKGROUND: Short tandem repeats (STRs) are the most widely used genetic markers in forensic genetics. Therefore, it is essential to document genetic population data of new kits designed for human identification purposes to enable laboratories to use these genetic systems to interpret and solve forensic casework. However, in Mexico, there are no studies with the PowerPlex Fusion 6C System, which includes 26 STRs (23 autosomal STRs and 3 Y-STRs). METHODS AND RESULTS: 600 DNA samples from Mexico City were subjected to genotyping using the PowerPlex Fusion 6C System. For autosomal STRs, 312 different alleles were observed. Combined PE and PD were 99.999999809866% and 99.99999999999999999999999818795%, respectively. Genetic distances and AMOVA test showed low but significant differentiation between Mexican populations. CONCLUSIONS: The results reported in this work demonstrate the efficacy of this system for human identification purposes in the population studied and justify its possible application in other Mexican Mestizo populations.

Use of Investigator 24plex GO! To analyse allele frequencies of 21 autosomal STRs in the population of Veracruz state, Mexico.

BACKGROUND: Mexican population databases for autosomal STRs are scarce, and no previous studies have been performed with the Qiagen Investigator 24plex GO! AIM: To analyse the frequency of 21 autosomal short tandem repeat (STR) loci and forensic parameters in individuals from Veracruz state, Mexico. SUBJECTS AND METHODS: A total of 234 unrelated individuals were analysed with the Investigator 24plex GO! Kit, which includes the following autosomal STRs: TH01, D3S1358, vWA, D21S11, TPOX, D1S1656, D12S391, SE33, D10S1248, D22S1045, D19S433, D8S133879, D2S1338, D2S441, D18S51, FGA, D16S539, CSF1PO, D13S317, D5S818, and D7S820. Allele frequencies, forensic parameters, and relationships with neighbouring Mexican populations were estimated. RESULTS: The STRs analysed were in Hardy-Weinberg Equilibrium (HWE). The combined matching probability and combined PE were 1.5266 E-24 and 0.999999988711, respectively. The D18S51 and SE33 loci presented the highest Ho (0.8974 and 0.8932) and PE (0.7902 and 0.7815), respectively. The highest PIC (0.9337) and PD (0.9894) values corresponded to SE33. Conversely, D22S1045 had the lowest PIC and PE (0.5533 and 0.3546, respectively). A population cluster among southern Mexican populations, which included non-differentiation between Guerrero and Veracruz states was detected. CONCLUSION: The forensic efficacy of the 21 STRs analysed by the Investigator 24plex GO! Kit was evaluated in the Veracruz state. Moreover, new population clusters that have not yet been described and are related to geographic regions were identified, and these are in agreement with previously reported ancestral differences.

Candidate pharmacological treatments for substance use disorder and suicide identified by gene co-expression network-based drug repositioning.

Patients with substance use disorders (SUD) are at high risk to die by suicide. So far, the neurobiology of the suicide-SUD association has not been elucidated. This study aimed to identify potential pharmacological targets among hub genes from brain gene co-expression networks of individuals with SUD in a suicidal and non-suicidal context. Post-mortem samples from the prefrontal cortex of 79 individuals were analyzed. Individuals were classified into the following groups: suicides with SUD (n = 28), suicides without SUD (n = 23), nonsuicides with SUD (n = 9), nonsuicides without SUD (n = 19). Gene expression profiles were evaluated with the Illumina HumanHT-12 v4 array. Co-expression networks were constructed in WGCNA using the differentially expressed genes found in the comparisons: (a) suicides with and without SUD and (b) nonsuicides with and without SUD. Hub genes were selected for drug-gene interaction testing in the DGIdb database. Among drugs interacting with hub genes in suicides we found MAOA inhibitors and dextromethorphan. In the nonsuicide individuals, we found interactions with eglumegad and antipsychotics (olanzapine, clozapine, loxapine). Modafinil was found to interact with genes in both suicides and nonsuicides. These drugs represent possible candidate treatments for patients with SUD with and without suicidal behavior and their study in each context is encouraged.

Paternal lineages and forensic parameters based on 23 Y-STRs (Powerplex® Y23) in Mestizo males from Mexico City.

We analyzed 307 Mexican-Mestizo (admixed) males from Mexico City with the Powerplex® Y23 system. The complete list of Y-STR haplotypes was uploaded into the YHRD database (accession number YA004275). The discriminatory capacity (98.70 %) and gene diversity (D = 99.99 %) were calculated, improving the haplotype diversity regarding previous studies in Mexico based on 17 Y-STRs and 12 Y-STRs. Haplogroup distribution assignment was inferred by means of two different online-available algorithms. The Native American Q* haplogroup was the most frequent (66.2 %), followed by the European R1b lineage (19.5 %). In addition, eight Eurasian (3.9%) and two African (6.6%) haplogroups were observed in this population sample from Mexico City. Interestingly, AMOVA test showed a low but significant differentiation among Mexican-Mestizos (Fst = 1.52%; p = 0.0000), suggesting that four population clusters allow to explain their genetic structure according to geographic criteria: north, west, center, and south.

Brain Gene Expression-DNA Methylation Correlation in Suicide Completers: Preliminary Results.

BACKGROUND: Gene expression alterations have been implicated in suicide pathology. However, the study of the regulatory effect of DNA methylation on gene expression in the suicidal brain has been restricted to candidate genes. OBJECTIVE: The objective of the study was to identify genes whose expression levels are correlated with DNA methylation in the prefrontal cortex of suicides. METHODS: Postmortem prefrontal cortex samples from 21 suicides and six non-suicides were collected. Transcriptomic and DNA methylation profiles were evaluated with microarrays; cis correlations between gene expression and CpG methylation were screened. We then analyzed the presence of transcription factor (TF) binding sites (TFBS) at CpG sites correlated with gene expression. Gene expression of TFs involved in neurodevelopmental binding to predicted TFBS was determined in the BrainSpan database. RESULTS: We identified 22 CpG sites whose methylation levels correlated with gene expression in the prefrontal cortex of suicides. Genes annotated to identified CpG sites were involved in neurodevelopment (BBS4, NKX6-2, AXL, CTNND1, and MBP) and polyamine metabolism (polyamine oxidase [PAOX]). Such correlations were not detected in the nonsuicide group. Nine TFs (USF1, TBP, SF1, NRF1, RFX1, SP3, PKNOX1, MAZ, and POU3F2) showed differential expression in pre- and post-natal developmental periods, according to BrainSpan database. CONCLUSIONS: The integration of different omic technologies provided novel candidates for the investigation of genes whose expression is altered in the suicidal brain and their potential regulatory mechanisms.

Exploratory analysis of genetic variants influencing molecular traits in cerebral cortex of suicide completers.

Genetic factors have been implicated in suicidal behavior. It has been suggested that one of the roles of genetic factors in suicide could be represented by the effect of genetic variants on gene expression regulation. Alteration in the expression of genes participating in multiple biological systems in the suicidal brain has been demonstrated, so it is imperative to identify genetic variants that could influence gene expression or its regulatory mechanisms. In this study, we integrated DNA methylation, gene expression, and genotype data from the prefrontal cortex of suicides to identify genetic variants that could be factors in the regulation of gene expression, generally called quantitative trait locus (xQTLs). We identify 6,224 methylation quantitative trait loci and 2,239 expression quantitative trait loci (eQTLs) in the prefrontal cortex of suicide completers. The xQTLs identified influence the expression of genes involved in neurodevelopment and cell organization. Two of the eQTLs identified (rs8065311 and rs1019238) were previously associated with cannabis dependence, highlighting a candidate genetic variant for the increased suicide risk in subjects with substance use disorders. Our findings suggest that genetic variants may regulate gene expression in the prefrontal cortex of suicides through the modulation of promoter and enhancer activity, and to a lesser extent, binding transcription factors.

Genetic Affiliation of Pre-Hispanic and Contemporary Mayas Through Maternal Linage.

Maya civilization developed in Mesoamerica and encompassed the Yucatan Peninsula, Guatemala, Belize, part of the Mexican states of Tabasco and Chiapas, and the western parts of Honduras and El Salvador. This civilization persisted approximately 3,000 years and was one of the most advanced of its time, possessing the only known full writing system at the time, as well as art, sophisticated architecture, and mathematical and astronomical systems. This civilization reached the apex of its power and influence during the Preclassic period, from 2000 BCE to 250 CE. Genetic variation in the pre-Hispanic Mayas from archaeological sites in the Mexican states of Yucatan, Chiapas, Quintana Roo, and Tabasco and their relationship with the contemporary communities in these regions have not been previously studied. Consequently, the principal aim of this study was to determine mitochondrial DNA (mtDNA) variation in the pre-Hispanic Maya population and to assess the relationship of these individuals with contemporary Mesoamerican Maya and populations from Asia, Beringia, and North, Central, and South America. Our results revealed interactions and gene flow between populations in the different archaeological sites assessed in this study. The mtDNA haplogroup frequency in the pre-Hispanic Maya population (60.53%, 34.21%, and 5.26% for haplogroups A, C, and D, respectively) was similar to that of most Mexican and Guatemalan Maya populations, with haplogroup A exhibiting the highest frequency. Haplogroup B most likely arrived independently and mixed with populations carrying haplogroups A and C based on its absence in the pre-Hispanic Mexican Maya populations and low frequencies in most Mexican and Guatemalan Maya populations, although this also may be due to drift. Maya and Ciboneys sharing haplotype H10 belonged to haplogroup C1 and haplotype H4 of haplogroup D, suggesting shared regional haplotypes. This may indicate a shared genetic ancestry, suggesting more regional interaction between populations in the circum-Caribbean region than previously demonstrated. Haplotype sharing between the pre-Hispanic Maya and the indigenous populations from Asia, the Aleutian Islands, and North, Central, and South America provides evidence for gene flow from the ancestral Amerindian population of the pre-Hispanic Maya to Central and South America.

Forensic parameters and population structure based on 21 autosomal STRs with the investigator 24plex QS in mestizos from the Mexico City population.

Allele frequencies and forensic parameters for 21 STR autosomal markers (CSF1PO, D10S1248, D12S391, D13S317,D16S539, D18S51, D19S433, D1S1656,D21S11, D22S1045, D2S1338, D2S441, D3S1358, D5S818, D7S820, D8S1179, FGA, SE33, TH01, TPOX and vWA) were reported in 289 unrelated individuals from Mexico City, Mexico. In addition, an interpopulation analysis was performed including other world populations. In brief, the established population database of 21 autosomal STR markers in the present work is adequate for human identification purposes.

Maternal admixture and population structure in Mexican-Mestizos based on mtDNA haplogroups.

The maternal ancestry (mtDNA) has important applications in different research fields, such as evolution, epidemiology, identification, and human population history. This is particularly interesting in Mestizos, which constitute the main population in Mexico (∼93%) resulting from post-Columbian admixture between Spaniards, Amerindians, and African slaves, principally. Consequently, we conducted minisequencing analysis (SNaPshot) of 11 mitochondrial single-nucleotide polymorphisms in 742 Mestizos of 10 populations from different regions in Mexico. The predominant maternal ancestry was Native American (92.9%), including Haplogroups A, B, C, and D (47, 23.7, 15.9, and 6.2%, respectively). Conversely, European and African ancestries were less frequent (5.3 and 1.9%, respectively). The main characteristics of the maternal lineages observed in Mexican-Mestizos comprised the following: 1) contrasting geographic gradient of Haplogroups A and C; 2) increase of European lineages toward the Northwest; 3) low or absent, but homogeneous, African ancestry throughout the Mexican territory; 4) maternal lineages in Mestizos roughly represent the genetic makeup of the surrounding Amerindian groups, particularly toward the Southeast, but not in the North and West; 5) continuity over time of the geographic distribution of Amerindian lineages in Mayas; and 6) low but significant maternal population structure (FST = 2.8%; P = 0.0000). The average ancestry obtained from uniparental systems (mtDNA and Y-chromosome) in Mexican-Mestizos was correlated with previous ancestry estimates based on autosomal systems (genome-wide single-nucleotide polymorphisms and short tandem repeats). Finally, the comparison of paternal and maternal lineages provided additional information concerning the gender bias admixture, mating patterns, and population structure in Mestizos throughout the Mexican territory.

High polygenic burden is associated with blood DNA methylation changes in individuals with suicidal behavior.

Suicidal behavior is result of the interaction of several contributors, including genetic and environmental factors. The integration of approaches considering the polygenic component of suicidal behavior, such as polygenic risk scores (PRS) and DNA methylation is promising for improving our understanding of the complex interplay between genetic and environmental factors in this behavior. The aim of this study was the evaluation of DNA methylation differences between individuals with high and low genetic burden for suicidality. The present study was divided into two phases. In the first phase, genotyping with the Psycharray chip was performed in a discovery sample of 568 Mexican individuals, of which 149 had suicidal behavior (64 individuals with suicidal ideation, 50 with suicide attempt and 35 with completed suicide). Then, a PRS analysis based on summary statistics from the Psychiatric Genomic Consortium was performed in the discovery sample. In a second phase, we evaluated DNA methylation differences between individuals with high and low genetic burden for suicidality in a sub-sample of the discovery sample (target sample) of 94 subjects. We identified 153 differentially methylated sites between individuals with low and high-PRS. Among genes mapped to differentially methylated sites, we found genes involved in neurodevelopment (CHD7, RFX4, KCNA1, PLCB1, PITX1, NUMBL) and ATP binding (KIF7, NUBP2, KIF6, ATP8B1, ATP11A, CLCN7, MYLK, MAP2K5). Our results suggest that genetic variants might increase the predisposition to epigenetic variations in genes involved in neurodevelopment. This study highlights the possible implication of polygenic burden in the alteration of epigenetic changes in suicidal behavior.

Brain Gene Expression-DNA Methylation Correlation in Suicide Completers: Preliminary Results

Abstract Background: Gene expression alterations have been implicated in suicide pathology. However, the study of the regulatory effect of DNA methylation on gene expression in the suicidal brain has been restricted to candidate genes. Objective: The objective of the study was to identify genes whose expression levels are correlated with DNA methylation in the prefrontal cortex of suicides. Methods: Postmortem prefrontal cortex samples from 21 suicides and six non-suicides were collected. Transcriptomic and DNA methylation profiles were evaluated with microarrays; cis correlations between gene expression and CpG methylation were screened. We then analyzed the presence of transcription factor (TF) binding sites (TFBS) at CpG sites correlated with gene expression. Gene expression of TFs involved in neurodevelopmental binding to predicted TFBS was determined in the BrainSpan database. Results: We identified 22 CpG sites whose methylation levels correlated with gene expression in the prefrontal cortex of suicides. Genes annotated to identified CpG sites were involved in neurodevelopment (BBS4, NKX6-2, AXL, CTNND1, and MBP) and polyamine metabolism (polyamine oxidase [PAOX]). Such correlations were not detected in the non-suicide group. Nine TFs (USF1, TBP, SF1, NRF1, RFX1, SP3, PKNOX1, MAZ, and POU3F2) showed differential expression in pre- and post-natal developmental periods, according to BrainSpan database. Conclusions: The integration of different omic technologies provided novel candidates for the investigation of genes whose expression is altered in the suicidal brain and their potential regulatory mechanisms. (REV INVEST CLIN. 2020;72(5):283-92)