Charting the Y-chromosome ancestry of present-day Argentinean Mennonites

Application of Targeted Y-Chromosomal Capture Enrichment to Increase the Resolution of Native American Haplogroup Q

Y-chromosomal haplogroups and the Y-SNPs defining them are relevant for the exploration of male lineages, inference of paternal ancestry, and reconstruction of migration pathways, to name a few. Currently, over 300,000 Y-SNPs have been reported, defining 20 main haplogroups. However, ascertainment bias in the investigations has led to some haplogroups being overlooked, which hinders a representative depiction of certain populations and their migration events. For migration pattern analyses of the first settlers of the Americas, the Native American main founding lineage Q-M3 needs to be further investigated to allow clear genetic differentiation of individuals of different ethnogeographic origins. To increase the resolution within this haplogroup, a total of 7.45 Mb of the Y chromosome of 59 admixed South Americans of haplogroup Q was targeted for sequencing using hybridization capture enrichment. Data were combined with 218 publicly available sequences of Central and South Americans of haplogroup Q. After rigorous data processing, variants not meeting the quality criteria were excluded and 4128 reliable Y-SNPs were reported. A total of 2224 Y-SNPs had previously unknown positions in the phylogenetic tree, and 1291 of these are novel. The phylogenetic relationships between the Y-SNPs were established using the software SNPtotree in order to report a redesigned phylogenetic tree containing 300 branches, defined by 3400 Y-SNPs. The new tree introduces 117 previously undescribed branches and is the most comprehensive phylogenetic tree of the Native American haplogroup Q lineages to date. The 214 sequences were assigned to 135 different low- to high-resolution branches, while in the previous phylogenetic tree, only 195 sequences could be sorted into 14 low-resolution branches with the same quality criteria. The improved genetic differentiation of subhaplogroup Q-M3 has a great potential to resolve migration patterns of Native Americans.

The Second Highest Prevalence of Celiac Disease Worldwide: Genetic and Metabolic Insights in Southern Brazilian Mennonites

Celiac disease (CD), despite its high morbidity, is an often-underdiagnosed autoimmune enteropathy. Using a modified version of the Brazilian questionnaire of the 2013 National Health Survey, we interviewed 604 Mennonites of Frisian/Flemish origin that have been isolated for 25 generations. A subgroup of 576 participants were screened for IgA autoantibodies in serum, and 391 participants were screened for HLA-DQ2.5/DQ8 subtypes. CD seroprevalence was 1:29 (3.48%, 95% CI = 2.16-5.27%) and biopsy-confirmed CD was 1:75 (1.32%, 95% CI = 0.57-2.59%), which is superior to the highest reported global prevalence (1:100). Half (10/21) of the patients did not suspect the disease. HLA-DQ2.5/DQ8 increased CD susceptibility (OR = 12.13 [95% CI = 1.56-94.20], p = 0.003). The HLA-DQ2.5 carrier frequency was higher in Mennonites than in Brazilians (p = 7 × 10^-6). HLA-DQ8 but not HLA-DQ2.5 carrier frequency differed among settlements (p = 0.007) and was higher than in Belgians, a Mennonite ancestral population (p = 1.8 × 10^-6), and higher than in Euro-Brazilians (p = 6.5 × 10^-6). The glutathione pathway, which prevents reactive oxygen species-causing bowel damage, was altered within the metabolic profiles of untreated CD patients. Those with lower serological positivity clustered with controls presenting close relatives with CD or rheumatoid arthritis. In conclusion, Mennonites have a high CD prevalence with a strong genetic component and altered glutathione metabolism that calls for urgent action to alleviate the burden of comorbidities due to late diagnosis.

Preliminary study between Y chromosome haplogroups and chagasic cardiomyopathy manifestations in patients with Chagas disease

INTRODUCTION

Among patients with Chagas disease, men have a higher risk of worse pathological symptoms than women. We aimed to explore the role of the Y chromosome in men diagnosed with Chagas disease and assess the relationship between their ancestry and disease status.

METHODS

In this comparative study, we analyzed 150 men with unrelated non-chagasic disease (nCD) and 150 men with unrelated chagasic disease (CD). We assessed the serological diagnosis of Chagas disease, biochemical parameters, thoracic X-rays, electrocardiogram, and transthoracic echocardiography and determined the haplogroup by analyzing a set of 17 microsatellites from the Y chromosome. We examined the associations between common Y chromosome haplogroups and the clinical parameters of risk by logistic regression.

RESULTS

For all patients, the most common haplogroups were R1b (43%), G2a (9%), and E1b1b (9%). The R1b and G2a haplogroup was more frequent in men with nCD and CD, respectively. As expected, we observed a high proportion of symptomatic patients in the CD group independent of the haplogroups. Men from both groups classified as having the R1b haplogroup showed less clinical evidence of disease. Multivariate analysis showed that CD patients without R1b were about five times more likely to have a cardio-thorax index >0.5% (OR [odds ratio] = 5.1, 95% CI [confidence interval] = 3.31-8.17). Men without the R1b haplogroup were 2.5 times more likely to show EcoCG alterations (OR = 2.50, 95% CI = 0.16-3.94).

CONCLUSIONS

Our results provided evidence that the R1b haplogroup may have a potential protective cardiovascular effect for its carriers.

The genetic affinities of Gujjar and Ladakhi populations of India

The Union Territories of Jammu and Kashmir (J&K) and Ladakh in North India owing to their unique geographic location offer a wide variety of landscape from plains to high altitudes and is a congruence of many languages and cultural practices. Here, we present the genetic diversity studies of Gujjars from Jammu region of J&K and Ladakhi population based on a battery of autosomal single nucleotide polymorphisms (SNPs) and short tandem repeats (STRs), Y-chromosomal STRs and the control region of the mitochondrial genome. These two populations were observed to be genetically distant to each other as well as to other populations from India. Interestingly, Y-STR analyses showed a closer affinity of Gujjars to other nomadic populations of Pashtuns from Baghlans and Kunduz provinces of Afghanistan and Pashtuns and Sindhis of Pakistan. Gujjars exhibited lesser genetic diversity as compared to Ladakhi population. M30f and M9 were the most abundant mitochondrial haplogroups observed among Gujjars and Ladakhis, respectively. A lower matrilineal to patrilineal diversity was observed for both these populations. The current study presents the first comprehensive analysis of Gujjars and Ladakhis and reveals their unique genetic affiliations with other populations of the world.

A comprehensive portrait of Y-STR diversity of Indian populations and comparison with 129 worldwide populations

India, known for its rich cultural, linguistic and ethnic diversity, has attracted the attention of population geneticists to understand its genetic diversity employing autosomal, Y-chromosomal and mitochondrial DNA markers. Y-chromosomal short tandem repeats (Y-STRs) are useful in understanding population substructures and reveal the patrilineal affinities among populations. Previous studies on Indian populations based on Y-STR markers were either limited to restricted number of markers or focused on few selected populations. In this study we genotyped 407 unrelated male individuals from 12 states in India employing the suite of Y-STRs present in PowerPlex Y23 (Promega, Madison, WI, USA). These populations clustered genetically close to each other irrespective of their geographic co-ordinates and were characterized primarily by R1a, H and L haplogroups. Interestingly, comparison with 129 worldwide populations showed genetic affinity of the Indian populations with few populations from Europe and Levantine. This study presents the first pan-Indian landscape of 23 Y-STRs and serves as a useful resource for construction of an Indian Y-STR database.

The geographic mosaic of Ecuadorian Y-chromosome ancestry

Ecuadorians originated from a complex mixture of Native American indigenous people with Europeans and Africans. We analyzed Y-chromosome STRs (Y-STRs) in a sample of 415 Ecuadorians (145 using the AmpFlSTR^® Yfiler™ system [Life Technologies, USA] and 270 using the PowerPlex^®Y23 system [Promega Corp., USA]; hereafter Yfiler and PPY23, respectively) representing three main ecological continental regions of the country, namely Amazon rainforest, Andes, and Pacific coast. Diversity values are high in the three regions, and the PPY23 exhibits higher discrimination power than the Yfiler set. While summary statistics, AMOVA, and R_ST distances show low to moderate levels of population stratification, inferred ancestry derived from Y-STRs reveal clear patterns of geographic variation. The major ancestry in Ecuadorian males is European (61%), followed by an important Native American component (34%); whereas the African ancestry (5%) is mainly concentrated in the Northwest corner of the country. We conclude that classical procedures for measuring population stratification do not have the desirable sensitivity. Statistical inference of ancestry from Y-STRS is a satisfactory alternative for revealing patterns of spatial variation that would pass unnoticed when using popular statistical summary indices.

Genomic continuity of Argentinean Mennonites

Mennonites are Anabaptist communities that originated in Central Europe about 500 years ago. They initially migrated to different European countries, and in the early 18^th century they established their first communities in North America, from where they moved to other American regions. We aimed to analyze an Argentinean Mennonite congregation from a genome-wide perspective by way of investigating >580.000 autosomal SNPs. Several analyses show that Argentinean Mennonites have European ancestry without signatures of admixture with other non-European American populations. Among the worldwide datasets used for population comparison, the CEU, which is the best-subrogated Central European population existing in The 1000 Genome Project, is the dataset showing the closest genome affinity to the Mennonites. When compared to other European population samples, the Mennonites show higher inbreeding coefficient values. Argentinean Mennonites show signatures of genetic continuity with no evidence of admixture with Americans of Native American or sub-Saharan African ancestry. Their genome indicates the existence of an increased endogamy compared to other Europeans most likely mirroring their lifestyle that involve small communities and historical consanguineous marriages.