Weaving Mitochondrial DNA and Y-Chromosome Variation in the Panamanian Genetic Canvas

A review of ancestrality and admixture in Latin America and the caribbean focusing on native American and African descendant populations

Genomics can reveal essential features about the demographic evolution of a population that may not be apparent from historical elements. In recent years, there has been a significant increase in the number of studies applying genomic epidemiological approaches to understand the genetic structure and diversity of human populations in the context of demographic history and for implementing precision medicine. These efforts have traditionally been applied predominantly to populations of European origin. More recently, initiatives in the United States and Africa are including more diverse populations, establishing new horizons for research in human populations with African and/or Native ancestries. Still, even in the most recent projects, the under-representation of genomic data from Latin America and the Caribbean (LAC) is remarkable. In addition, because the region presents the most recent global miscegenation, genomics data from LAC may add relevant information to understand population admixture better. Admixture in LAC started during the colonial period, in the 15th century, with intense miscegenation between European settlers, mainly from Portugal and Spain, with local indigenous and sub-Saharan Africans brought through the slave trade. Since, there are descendants of formerly enslaved and Native American populations in the LAC territory; they are considered vulnerable populations because of their history and current living conditions. In this context, studying LAC Native American and African descendant populations is important for several reasons. First, studying human populations from different origins makes it possible to understand the diversity of the human genome better. Second, it also has an immediate application to these populations, such as empowering communities with the knowledge of their ancestral origins. Furthermore, because knowledge of the population genomic structure is an essential requirement for implementing genomic medicine and precision health practices, population genomics studies may ensure that these communities have access to genomic information for risk assessment, prevention, and the delivery of optimized treatment; thus, helping to reduce inequalities in the Western Hemisphere. Hoping to set the stage for future studies, we review different aspects related to genetic and genomic research in vulnerable populations from LAC countries.

A paleoepidemiological approach to the challenging differential diagnosis of an isolated 1500-year-old anomalous molar from Panamá

OBJECTIVE

This study seeks to quantify the presence and prevalence of specific genetic and infectious diseases in the pre-Colombian Panamanian population and uses these data to consider the plausibility of these diseases as causative factors in the development of an abnormal supernumerary cusp morphology in a 1500-year-old isolated molar recovered from Cerro Juan Díaz (Los Santos, Panama).

MATERIALS

267 individuals from pre-Columbian sites throughout Panama.

METHODS

The anomalous tooth was analyzed through macroscopic, odontometric, and radiographic means. Tentative differential diagnosis was performed using inferences from paleopathological features of the broader regional population.

RESULTS

The regional sample showed evidence of treponemal infection and developmental anomalies in 10.1% and 10.9% of individuals, respectively.

CONCLUSIONS

While not able to rule out three potential genetic conditions, more evidence was found to support the differential diagnosis of congenital syphilis as the causative agent leading to the development of abnormal supernumerary cusps in the isolated molar.

SIGNIFICANCE

This study demonstrates how characterizing disease experience in the population can assist in differential diagnoses at the individual level and cautions against the assumption that any one lesion in isolation is unique to only one specific pathological condition.

LIMITATIONS

The timing discrepancy between clinical descriptions of congenital syphilis and genetic disorders, lack of knowledge on pathophysiological mechanisms of the former, poor preservation of Treponema pathogen ancient DNA, and deficiencies in modern public health data from Panama limit the differential diagnosis.

SUGGESTIONS FOR FURTHER RESEARCH

Inclusion and serious contemplation of genetic diseases in paleopathological differential diagnoses is necessary.

Overview of the Americas’ First Peopling from a Patrilineal Perspective: New Evidence from the Southern Continent

Uniparental genetic systems are unique sex indicators and complement the study of autosomal diversity by providing landmarks of human migrations that repeatedly shaped the structure of extant populations. Our knowledge of the variation of the male-specific region of the Y chromosome in Native Americans is still rather scarce and scattered, but by merging sequence information from modern and ancient individuals, we here provide a comprehensive and updated phylogeny of the distinctive Native American branches of haplogroups C and Q. Our analyses confirm C-MPB373, C-P39, Q-Z780, Q-M848, and Q-Y4276 as the main founding haplogroups and identify traces of unsuccessful (pre-Q-F1096) or extinct (C-L1373*, Q-YP4010*) Y-chromosome lineages, indicating that haplogroup diversity of the founder populations that first entered the Americas was greater than that observed in the Indigenous component of modern populations. In addition, through a diachronic and phylogeographic dissection of newly identified Q-M848 branches, we provide the first Y-chromosome insights into the early peopling of the South American hinterland (Q-BY104773 and Q-BY15730) and on overlying inland migrations (Q-BY139813).