The paternal perspective of the Slovenian population and its relationship with other populations

A Machine-Learning-Based Approach to Prediction of Biogeographic Ancestry within Europe

Data obtained with the use of massive parallel sequencing (MPS) can be valuable in population genetics studies. In particular, such data harbor the potential for distinguishing samples from different populations, especially from those coming from adjacent populations of common origin. Machine learning (ML) techniques seem to be especially well suited for analyzing large datasets obtained using MPS. The Slavic populations constitute about a third of the population of Europe and inhabit a large area of the continent, while being relatively closely related in population genetics terms. In this proof-of-concept study, various ML techniques were used to classify DNA samples from Slavic and non-Slavic individuals. The primary objective of this study was to empirically evaluate the feasibility of discerning the genetic provenance of individuals of Slavic descent who exhibit genetic similarity, with the overarching goal of categorizing DNA specimens derived from diverse Slavic population representatives. Raw sequencing data were pre-processed, to obtain a 1200 character-long binary vector. A total of three classifiers were used-Random Forest, Support Vector Machine (SVM), and XGBoost. The most-promising results were obtained using SVM with a linear kernel, with 99.9% accuracy and F1-scores of 0.9846-1.000 for all classes.

Eye and hair color prediction of an early medieval adult and subadult skeleton using massive parallel sequencing technology

Phenotypic trait prediction in ancient DNA analysis can provide information about the external appearance of individuals from past human populations. Some studies predicting eye and hair color in ancient adult skeletons have been published, but not for ancient subadult skeletons, which are more prone to decay. In this study, eye and hair color were predicted for an early medieval adult skeleton and a subadult skeleton that was anthropologically characterized as a middle-aged man and a subadult of unknown sex about 6 years old. When processing the petrous bones, precautions were taken to prevent contamination with modern DNA. The MillMix tissue homogenizer was used for grinding, 0.5 g of bone powder was decalcified, and DNA was purified in Biorobot EZ1. The PowerQuant System was used for quantification and a customized version of the HIrisPlex panel for massive parallel sequencing (MPS) analysis. Library preparation and templating were performed on the HID Ion Chef Instrument and sequencing on the Ion GeneStudio S5 System. Up to 21 ng DNA/g of powder was obtained from ancient petrous bones. Clean negative controls and no matches with elimination database profiles confirmed no contamination issue. Brown eyes and dark brown or black hair were predicted for the adult skeleton and blue eyes and brown or dark brown hair for the subadult skeleton. The MPS analysis results obtained proved that it is possible to predict hair and eye color not only for an adult from the Early Middle Ages, but also for a subadult skeleton dating to this period.

Kinship analysis of 5th- to 6th-century skeletons of Romanized indigenous people from the Bled-Pristava archaeological site

The familial relationship between skeletons buried together in a shared grave is important for understanding the burial practices of past human populations. Four skeletons were excavated from the Late Antiquity part of the Bled-Pristava burial site in Slovenia, dated to the 5th to 6th century. They were anthropologically characterized as two adults (a middle-aged man and a young woman) and two non-adults (of unknown sex). Based on stratigraphy, the skeletons were considered to be buried simultaneously in one grave. Our aim was to determine whether the skeletons were related. Petrous bones and teeth were used for genetic analysis. Specific precautions were followed to prevent contamination of ancient DNA with contemporary DNA, and an elimination database was established. Bone powder was obtained using a MillMix tissue homogenizer. Prior to extracting the DNA using Biorobot EZ1, 0.5 g of powder was decalcified. The PowerQuant System was used for quantification, various autosomal kits for autosomal short tandem repeat (STR) typing, and the PowerPlex Y23 kit for Y-STR typing. All analyses were performed in duplicate. Up to 28 ng DNA/g of powder was extracted from the samples analyzed. Almost full autosomal STR profiles obtained from all four skeletons and almost full Y-STR haplotypes obtained from two male skeletons were compared, and the possibility of a familial relationship was evaluated. No amplification was obtained in the negative controls, and no match was found in the elimination database. Autosomal STR statistical calculations confirmed that the adult male was the father of two non-adult individuals and one young adult individual from the grave. The relationship between the males (father and son) was additionally confirmed by an identical Y-STR haplotype that belonged to the E1b1b haplogroup, and a combined likelihood ratio for autosomal and Y-STRs was calculated. Kinship analysis confirmed with high confidence (kinship probability greater than 99.9% was calculated for all three children) that all four skeletons belonged to the same family (a father, two daughters, and a son). Through genetic analysis, the burial of members of the same family in a shared grave was confirmed as a burial practice of the population living in the Bled area in Late Antiquity.

Distribution of Y-chromosome haplogroups in Serbian population groups originating from historically and geographically significant distinct parts of the Balkan Peninsula

Our study enrolled 1200 Serbian males originating from three geographical regions in the Balkan Peninsula inhabited by Serbs: present-day Serbia, regions of Old Herzegovina and Kosovo and Metohija. These samples were genotyped using the combination of 23 Y-chromosomal short tandem repeats (Y-STRs) loci and 17 Ychromosomal single nucleotide polymorphisms (Y-SNPs) loci for the haplotype and haplogroup analysis in order to characterize in detail Y chromosome flow in the recent history. Serbia's borders have changed through history, forcing Serbs constantly to migrate to different regions of Balkan Peninsula. The most significant migration waves in the recent history towards present-day Serbia occurred from the regions of Old- Herzegovina and Kosovo and Metohija that lie in the south-west/south. High haplotype diversity and discrimination capacity were observed in all three datasets, with the highest number of unique haplotypes (381) and discrimination capacity (0.97) detected in the samples originating from the present-day Serbia. Haplogroup composition didn't differ significantly among datasets, with three dominant haplogroups (I-M170, E-P170 and R-M198), and haplogroup I-M170 being the most frequent in all three datasets. Haplogroup E-P170 was the second most dominant in the dataset originating from geographical region of Kosovo and Metohija, whereas haplogroup R-M198 was the second most prevalent in the dataset from historical region of Old Herzegovina. Based on the phylogenetic three for haplogroup I constructed within this study, haplogroup I2a1-P37.2 was the most dominant within all three datasets, especially in the dataset from historical region of Old Herzegovina, where 182 out of 400 samples were derived for SNP P37.2. Genetic distances between three groups of samples, evaluated by the Fst and Rst statistical values, and further visualized through multidimensional scaling plot, showed great genetic similarity between datasets from Old Herzegovina and present-day Serbia. Genetic difference in the haplogroup distribution and frequency between datasets from historical region of Old Herzegovina and from geographical region of Kosovo and Metohija was confirmed with highest Fst and Rst vaules. In this study we have distinguished genetic structure, diversity and haplogroup frequencies within 1200 Serbian males from three datasets, relationships among them as well as with other Balkan and European populations, which is useful for studying recent demographic history.

Mutations in Collagen Genes in the Context of an Isolated Population

Genetic studies of population isolates have great potential to provide a unique insight into genetic differentiation and phenotypic expressions. Galičnik village is a population isolate located in the northwest region of the Republic of North Macedonia, established around the 10th century. Alport syndrome-linked nephropathy with a complex inheritance pattern has been described historically among individuals in the village. In order to determine the genetic basis of the nephropathies and to characterize the genetic structure of the population, 23 samples were genotyped using a custom-made next generation sequencing panel and 111 samples using population genetic markers. We compared the newly obtained population data with fifteen European population data sets. NGS analysis revealed four different mutations in three different collagen genes in twelve individuals within the Galičnik population. The genetic isolation and small effective population size of Galičnik village have resulted in a high level of genomic homogeneity, with domination of R1a-M458 and R1b-U106* haplogroups. The study explains complex autosomal in cis digenic and X-linked inheritance patterns of nephropathy in the isolated population of Galičnik and describes the first case of Alport syndrome family with three different collagen gene mutations.

Y-Chromosome Genetic Analysis of Modern Polish Population

The study presents a full analysis of the Y-chromosome variability of the modern male Polish population. It is the first study of the Polish population to be conducted with such a large set of data (2,705 individuals), which includes genetic information from inhabitants of all voivodeships, i.e., the first administrative level, in the country and the vast majority of its counties, i.e., the second level. In addition, the available data were divided into clusters corresponding to more natural geographic regions. Genetic analysis included the estimation of F_ST distances, the visualization with the use of multidimensional scaling plots and analysis of molecular variance. Y-chromosome binary haplogroups were classified and visualized with the use of interpolation maps. Results showed that the level of differentiation within Polish population is quite low, but some differences were indicated. It was confirmed that the Polish population is characterized by a high degree of homogeneity, with only slight genetic differences being observed at the regional level. The use of regional clustering as an alternative to counties and voivodeships provided a more detailed view of the genetic structure of the population. Those regional differences identified in the present study highlighted the need for additional division of the population by cultural and ethnic criteria in such studies rather than just by geographical or administrative regionalization.

Y chromosome genetic data defined by 23 short tandem repeats in a Serbian population on the Balkan Peninsula

BACKGROUND

Serbs mainly live in the territory of the recently re-established state of Serbia. However, the turbulent history in the Balkan Peninsula has led to settlement of Serbs not only within present day Serbia, but also in different parts of neighbouring countries.

AIM

To define polymorphisms of 23 Y-chromosomal short tandem repeat (STR) loci in a modern Serbian population from the central part of the Balkan Peninsula.

SUBJECTS AND METHODS

The reference sample consisted of 303 men declared as Serbs over three generations. Localities of the collected materials include the territories of Serbia, Bosnia and Herzegovina, Croatia and Montenegro. DNA samples were typed using the PowerPlex^®Y23 amplification kit.

RESULTS

The highest locus diversity was observed for DYS385 and DYS481. In this study the most abundant haplogroups were I2a, E1b1b, R1a and I1. The largest genetic distances between the Serbs and other close Southern Slavs were for the Macedonians and Slovenians.

CONCLUSION

This study is the first one to define STR polymorphism of Serbian people not only from Serbia but also from other parts of the Balkan Peninsula. The presented genetic data may be useful in further examinations of the genesis and genetic structuring of the present-day Serbian gene pool.

Genetic Landscape of Slovenians: Past Admixture and Natural Selection Pattern

The Slovenian territory played a crucial role in the past serving as gateway for several human migrations. Previous studies used Slovenians as a source population to interpret different demographic events happened in Europe but not much is known about the genetic background and the demographic history of this population. Here, we analyzed genome-wide data from 96 individuals to shed light on the genetic role and history of the Slovenian population. Y chromosome diversity splits into two major haplogroups R1b and R1a with the latter suggesting a genetic contribution from the steppe. Slovenian individuals are more closely related to Northern and Eastern European populations than Southern European populations even though they are geographically closer. This pattern is confirmed by an admixture and clustering analysis. We also identified a single stream of admixture events between the Slovenians with Sardinians and Russians around ∼2630 BCE (2149-3112). Using ancient samples, we found a significant admixture in Slovenians using Yamnaya and the early Neolithic Hungarians as sources, dated around ∼1762 BCE (1099-2426) suggesting a strong contribution from the steppe to the foundation of the observed modern genetic diversity. Finally, we looked for signals of selection in candidate variants and we found significant hits in HERC2 and FADS responsible for blue eye color and synthesis of long-chain unsaturated fatty acids, respectively, when Slovenians were compared to Southern Europeans. While the comparison was done with Eastern Europeans, we identified significant signals in PKD2L1 and IL6R which are genes associated with taste and coronary artery disease, respectively.

The lack of association between angiotensin-converting enzyme gene insertion/deletion polymorphism and nicotine dependence in multiple sclerosis

OBJECTIVE

Blood-borne angiotensin II is generated from angiotensinogen via cleavage by renin and angiotensin-converting enzyme (ACE), an enzymatic cascade known as the renin-angiotensin system (RAS). Several lines of evidence indicate that ACE, beyond its classical role of mediating blood pressure regulation, might contribute to the etiology of substance addictions by influencing dopaminergic signaling. A functional insertion/deletion (I/D) polymorphism of the ACE gene was associated with risk for being a smoker among individuals with depression and with smoking severity in studies comprising patients with depression and healthy controls. Several reports have described significantly increased ACE activity in cerebrospinal fluid and serum among MS patients. Furthermore, in our previous work with MS patients from Croatian and Slovenian populations, we demonstrated that the ACE-I/D polymorphism contributes to an elevated MS risk among male patients. Here we investigated whether the ACE-I/D polymorphism might influence smoking behavior among patients with MS.

PATIENTS AND METHODS

Genotyping was performed in 521 patients (males/females: 139/382) using polymerase chain reaction.

RESULTS

We revealed no significant differences in ACE genotype and allele frequencies between smokers and nonsmokers and no significant association between the ACE-I/D polymorphism and either pack-year smoking history or number of cigarettes smoked daily (p > .05, respectively).

CONCLUSION

The ACE-I/D polymorphism does not contribute either to risk for nicotine dependence or to smoking severity among MS patients. In the context of reports on the ACE-I/D polymorphism and nicotine dependence among healthy controls and patients with depression, we may speculate that the mechanism by which this polymorphism influences nicotine dependence risk differs in MS compared to depression, although not compared to a healthy population. In addition to angiotensin II, other potential ACE substrates, such as substance P and neurotensin, which also influence dopaminergic neurotransmission (and are proposed to be associated with MS), may deserve study in future.

Molecular diversity of 23 Y-chromosome short tandem repeat loci in the population of Tuzla Canton, Bosnia and Herzegovina

BACKGROUND

Tuzla Canton is the most populated region in the ethnically mixed territory of Bosnia and Herzegovina, whose genetic analysis could provide an insight into past demographic events.

AIM

Analysis of 23 Y-chromosome STR markers in the population of Tuzla Canton and investigation of the genetic relationship of the male population of the Tuzla Canton and that of the larger Bosnian and Herzegovinian population as well as neighbouring and other European populations.

SUBJECTS AND METHODS

The study was conducted among 100 unrelated healthy adult males from Tuzla Canton that have been genotyped using 23 Y-STR loci included in the PowerPlex Y23 kit. Statistical parameters such as haplotype diversity and allele frequencies were calculated, as well as the R_st-based genetic distances between the new dataset and those from Bosnia and Herzegovina and elsewhere, which were then visualised through multi-dimensional scaling plot and neighbour-joining phylogenetic tree analyses.

RESULTS

The PowerPlex Y23 kit has shown high discrimination capacity, as all 100 individuals have unique haplotypes. The newly incorporated loci seem to be highly informative. Population comparison reveals no statistically significant differences between the study population and the general Bosnian-Herzegovinian population, and between the study population and neighbouring populations.

CONCLUSION

These results could be used as an additional investigation of the genetic relationship between the regional populations in Bosnia and Herzegovina and neighbouring human populations, as well as for further human population and forensic genetics studies.

The maternal perspective for five Slovenian regions: The importance of regional sampling

BACKGROUND

The Slovenian territory is geographically positioned between the Alps, Adriatic Sea, Pannonian basin and the Dinaric Mountains and, as such, has served as a passageway for various populations in different periods of time. Turbulent historic events and diverse geography of the region have produced a diverse contemporary population whose genetic analysis could provide insight into past demographic events.

AIM

The aims of this study were to characterize the Slovenian mitochondrial gene pool at the micro-geographic level and to compare it with surrounding populations.

SUBJECTS AND METHODS

A total of 402 individuals from five Slovenian regions were analysed in this study by typing HVR I, HVR II and coding region polymorphisms of mtDNA.

RESULTS

Analysis revealed 47 haplogroups and sub-haplogroups, the most common of which were H*, H1, J1c, T2 and U5a. Intra-population comparisons revealed a sharp gradient of the J1c haplogroup between Slovenian regions, with a peak frequency of 24.5% being observed in the population of the Littoral Region.

CONCLUSION

The sharp gradient of the J1c haplogroup between Slovenian regions is in line with the archaeological horizon known as Impressed Ware culture and could, therefore, represent a genetic trace of the early Neolithic expansion route along the East Adriatic coastal region.

New clustering methods for population comparison on paternal lineages

The goal of this study is to show two new clustering and visualising techniques developed to find the most typical clusters of 18-dimensional Y chromosomal haplogroup frequency distributions of 90 Western Eurasian populations. The first technique called "self-organizing cloud (SOC)" is a vector-based self-learning method derived from the Self Organising Map and non-metric Multidimensional Scaling algorithms. The second technique is a new probabilistic method called the "maximal relation probability" (MRP) algorithm, based on a probability function having its local maximal values just in the condensation centres of the input data. This function is calculated immediately from the distance matrix of the data and can be interpreted as the probability that a given element of the database has a real genetic relation with at least one of the remaining elements. We tested these two new methods by comparing their results to both each other and the k-medoids algorithm. By means of these new algorithms, we determined 10 clusters of populations based on the similarity of haplogroup composition. The results obtained represented a genetically, geographically and historically well-interpretable picture of 10 genetic clusters of populations mirroring the early spread of populations from the Fertile Crescent to the Caucasus, Central Asia, Arabia and Southeast Europe. The results show that a parallel clustering of populations using SOC and MRP methods can be an efficient tool for studying the demographic history of populations sharing common genetic footprints.

The place of Slovakian paternal diversity in the clinal European landscape

BACKGROUND

Several demographic events have been postulated to explain the contemporaneous structure of European genetic diversity. First, an initial settlement of the continent by anatomically modern humans; second, the re-settlement of northern latitudes after the Last Glacial Maximum; third, the demic diffusion of Neolithic farmers from the Near East; and, fourth, several historical events such as the Slavic migration.

AIM

The aim of this study was to provide a more integrated picture of male-specific genetic relationships of Slovakia within the broader pan-European genetic landscape.

SUBJECTS AND METHODS

This study analysed a new Y-chromosome data-set (156 individuals) for both SNP and STR polymorphisms in population samples from five different Slovakian localities.

RESULTS

It was found that the male diversity of Slovakia is embedded in the clinal pattern of the major R1a and R1b clades extending over the continent and a similar pattern of population structure is found with Y-specific SNP or STR variation.

CONCLUSION

The highly significant correlation between the results based on fast evolving STRs on one hand and slow evolving SNPs on the other hand suggests a recent timeframe for the settlement of the area.