Genetic Overview of the Maya Populations: Mitochondrial DNA Haplogroups

We identified the mitochondrial DNA haplogroups A, B, C and D in 75 present-day Maya individuals, 24 Maya individuals of the colonial period and one pre-Columbian Maya individual from Quintana Roo, Mexico. We examined these data together with those of 21 Maya populations accounting for 647 present-day Maya individuals and 104 ancient Maya individuals. A demographic study based on the analysis of fertility and endogamy was carried out in two modern Maya populations to identify cultural factors that influence the mitochondrial haplogroup genetic diversity. Most present-day and ancient Maya populations show a distribution pattern of mitochondrial haplogroup frequencies A, C, B and D in decreasing order, with haplogroup D absent in several populations. Considering only modern Maya populations with at least 50 individuals analyzed, the present-day Tzotzil and Lacandon populations from Chiapas show the higher and lower genetic diversities, 0.706 and 0.025 respectively. Our results show small genetic differences between the Maya populations with exception of the present-day Tojolabal and Lacandon populations from Chiapas. The present-day Lacandon population from Chiapas is different to other Maya populations in showing almost only haplogroup A. This result suggests a long history of isolation and endogamy as well as a possible founder effect inside the Lacandonian rain-forest. The contemporary Tojolabal population is the only one with an unusual mitochondrial haplogroup pattern exhibiting a frequency of haplogroup B higher than A and the absence of haplogroup C. With a small sample size, the pre-Columbian Copan Maya show a high content of haplogroup C and a low frequency of haplogroup D. The genetic homogeneity of the Maya populations is indicative of a common origin and nearly continuous gene flow in the long-term within a general isolation of the whole group, conversely to the Nahua populations that had different origins. Our demographic study showed high fertility rates and high levels of endogamy in the present-day Maya populations from Quintana Roo here analyzed that are consistent with their general low genetic diversity. We propose that the genetic similarity among ancient and present-day Maya populations persists due to a strong sense of social cohesion and identity that impacts their marriage practices maintaining this cultural group isolated. These factors have constrained gene flow inside the Maya region and impeded the differentiation among the Maya. Discernment of genetic differentiation within the peninsula is constrained by the lack of sampling documentation in the literature

Mendelian Randomization Analysis of the Relationship Between Native American Ancestry and Gallbladder Cancer Risk

Background A strong association between the proportion of Native American ancestry and the risk of gallbladder cancer (GBC) has been reported in observational studies. Chileans show the highest incidence of GBC worldwide, and the Mapuche are the largest Native American people in Chile. We set out to investigate the causal association between Native American Mapuche ancestry and GBC risk, and the possible mediating effects of gallstone disease and body mass index (BMI) on this association. Methods Markers of Mapuche ancestry were selected based on the informativeness for assignment measure and then used as instrumental variables in two-sample mendelian randomization (MR) analyses and complementary sensitivity analyses. Result We found evidence of a causal effect of Mapuche ancestry on GBC risk (inverse variance-weighted (IVW) risk increase of 0.8% for every 1% increase in Mapuche ancestry proportion, 95% CI 0.4% to 1.2%, p = 6.6×10-5). Mapuche ancestry was also causally linked to gallstone disease (IVW risk increase of 3.6% per 1% increase in Mapuche proportion, 95% CI 3.1% to 4.0%, p = 1.0×10-59), suggesting a mediating effect of gallstones in the relationship between Mapuche ancestry and GBC. In contrast, the proportion of Mapuche ancestry showed a negative causal effect on BMI (IVW estimate -0.006 kg/m2 per 1% increase in Mapuche proportion, 95% CI -0.009 to -0.003, p = 4.4×10-5). Conclusions The results presented here may have significant implications for GBC prevention and are important for future admixture mapping studies. Given that the association between Mapuche ancestry and GBC risk previously noted in observational studies appears to be causal, primary and secondary prevention strategies that take into account the individual proportion of Mapuche ancestry could be particularly efficient

Rare coding variants in PLCG2, ABI3, and TREM2 implicate microglial-mediated innate immunity in Alzheimer's disease

We identified rare coding variants associated with Alzheimer’s disease (AD) in a 3-stage case-control study of 85,133 subjects. In stage 1, 34,174 samples were genotyped using a whole-exome microarray. In stage 2, we tested associated variants (P<1×10-4) in 35,962 independent samples using de novo genotyping and imputed genotypes. In stage 3, an additional 14,997 samples were used to test the most significant stage 2 associations (P<5×10-8) using imputed genotypes. We observed 3 novel genome-wide significant (GWS) AD associated non-synonymous variants; a protective variant in PLCG2 (rs72824905/p.P522R, P=5.38×10-10, OR=0.68, MAFcases=0.0059, MAFcontrols=0.0093), a risk variant in ABI3 (rs616338/p.S209F, P=4.56×10-10, OR=1.43, MAFcases=0.011, MAFcontrols=0.008), and a novel GWS variant in TREM2 (rs143332484/p.R62H, P=1.55×10-14, OR=1.67, MAFcases=0.0143, MAFcontrols=0.0089), a known AD susceptibility gene. These protein-coding changes are in genes highly expressed in microglia and highlight an immune-related protein-protein interaction network enriched for previously identified AD risk genes. These genetic findings provide additional evidence that the microglia-mediated innate immune response contributes directly to AD development

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Espacio trasfronterizo entre Belice y México a principios del siglo XX. Análisis socio-demográfico del impacto de la migración en la formación familiar

Belice y México comparten características demográficas, culturales y económicas. Su gente fronteriza ha tenido procesos de sociabilidad, impactando en la formación de sus familias y su modo de asimilación a los lugares de destino al momento de migrar. Se evaluaron estos procesos a través de los registros civiles de nacimientos y defunciones de Corozal, Belice y del sur de Quintana Roo, México (1885 a 1955), con la finalidad de reconstruir las familias, de ahí se obtuvo información sobre su fecundidad y tipos de familias (endo/exogámicas). Los resultados muestran diferencias en estos rubros, por lo que cada grupo social (cultura íntima) vive diferente su proceso migratorio

ESPACIO TRASFRONTERIZO ENTRE BELICE Y MÉXICO A PRINCIPIOS DEL SIGLO XX. ANÁLISIS SOCIO-DEMOGRÁFICO DEL IMPACTO DE LA MIGRACIÓN EN LA FORMACIÓN FAMILIAR

Belice y México comparten características demográficas, culturales y económicas. Su gente fronteriza ha tenido procesos de sociabilidad, impactando en la formación de sus familias y su modo de asimilación a los lugares de destino al momento de migrar. Se evaluaron estos procesos a través de los registros civiles de nacimientos y defunciones de Corozal, Belice y del sur de Quintana Roo, México (1885 a 1955), con la finalidad de reconstruir las familias, de ahí se obtuvo información sobre su fecundidad y tipos de familias (endo/exogámicas). Los resultados muestran diferencias en estos rubros, por lo que cada grupo social (cultura íntima) vive diferente su proceso migratorio.   TRANSBORDER SPACE BETWEEN BELIZE AND MEXICO IN THE EARLY 20TH CENTURY: A SOCIO-DEMOGRAPHIC ANALYSIS OF THE IMPACT OF MIGRATION ON FAMILY FORMATION ABSTRACT Belize and Mexico share demographic, cultural and economic characteristics. Their bordering peoples have experienced sociability processes that have an impact on family formation and their mode of assimilation to their destinations when they migrate. These processes were evaluated through the civil registry of birth and death records in Corozal, Belize and South Quintana Roo, Mexico (from 1885 to 1955) with the purpose of reconstructing family composition. Information about fertility and family types (endo/exogamic families) was drawn from the same source. Results show differences in these areas. Each social group (intimate culture) thus has a different experience of its migratory process

La paleodemografía: ¿un instrumento para simular el comportamiento demográfico del pasado? Análisis comparativo con la demografía histórica en la Ciudad de México del siglo XIX.

En este estudio se emplearon los métodos de evaluación de la información y de análisis demográfico para examinar el comportamiento de dos series poblacionales de la Ciudad de México del siglo XIX que provienen de los restos esqueléticos que fueron exhumados en el Panteón de Santa Paula y de los registros de la Parroquia de Santa María. Los resultados muestran diferencias entre todos los análisis, y con ellos se construyeron dos escenarios demográficos, pues la demografía histórica refiere una fecundidad mayor que la determinada por la paleodemografía, lo cual ocasiona que los cálculos de la mortalidad sean por tanto disímiles. Estas diferencias provienen de las desiguales distribuciones de edad a la muerte, por lo que carece de sustento la idea de complementar el estudio demográfico de las poblaciones pretéritas con la combinación de estas disciplinas

Análisis antropofísico de una osamenta

This article presents the results of a physical-anthropological study carried out on the bones uncovered at the base of the San Felipe Fortress in Bacalar. The bones correspond to a Caucasian man, of middle age, living in the nineteenth century, and who according to the bone structure and the artifacts accompanying them possibly belonged to the privileged classes. This study aims to establish the identity of this person, determine what relationship he had with Bacalar and with the Fortress, and in which socio-historic time he lived and died. The importance of this person lies in the fact that he represents a reference point for the reconstruction of living conditions in Bacalar in the nineteenth century