Refining the Global Phylogeny of Mitochondrial N1a, X, and HV2 Haplogroups Based on Rare Mitogenomes from Croatian Isolates

Mitochondrial DNA (mtDNA) has been used for decades as a predominant tool in population genetics and as a valuable addition to forensic genetic research, owing to its unique maternal inheritance pattern that enables the tracing of individuals along the maternal lineage across numerous generations. The dynamic interplay between evolutionary forces, primarily genetic drift, bottlenecks, and the founder effect, can exert significant influence on genetic profiles. Consequently, the Adriatic islands have accumulated a subset of lineages that exhibits remarkable absence or rarity within other European populations. This distinctive genetic composition underscores the islands' potential as a significant resource in phylogenetic research, with implications reaching beyond regional boundaries to contribute to a global understanding. In the initial attempt to expand the mitochondrial forensic database of the Croatian population with haplotypes from small isolated communities, we sequenced mitogenomes of rare haplogroups from different Croatian island and mainland populations using next-generation sequencing (NGS). In the next step and based on the obtained results, we refined the global phylogeny of haplogroup N1a, HV2, and X by analyzing rare haplotypes, which are absent from the current phylogenetic tree. The trees were based on 16 novel and 52 previously published samples, revealing completely novel branches in the X and HV2 haplogroups and a new European cluster in the ancestral N1a variant, previously believed to be an exclusively African-Asian haplogroup. The research emphasizes the importance of investigating geographically isolated populations and their unique characteristics within a global context.

Linking infant size and early growth with maternal lifestyle and breastfeeding - the first year of life in the CRIBS cohort

BACKGROUND

Every third child in Croatia is classed as overweight or obese. Infant growth can represent early warning signs for obesity.

AIM

To detect early risk factors for obesity by investigating infant size and early growth trajectories and their association with maternal lifestyle and breastfeeding.

SUBJECTS AND METHODS

Ninety-eight mother-child pairs from the Croatian Islands' Birth Cohort Study (CRIBS) cohort were included in the study. Data were collected from questionnaires and medical records. Growth data were converted to Z-scores using World Health Organisation (WHO) standards and used as the primary outcome.

RESULTS

Z-score trajectories in the first year of life were in line with WHO standards. A direct link between infant size and maternal socioeconomic status (SES) or breastfeeding was not detected. However, child weight gain in the first 6 months was associated with maternal body mass index (BMI) before pregnancy (p < 0.01). A positive association was also established between breastfeeding and maternal SES and mothers that report an unhealthy diet have heavier children (p < 0.05, respectively).

CONCLUSION

Infant size and early growth in Croatia is in line with WHO standards and risk factors for obesity development were detectable in the first year of life, but not highly pronounced. However, more effective BMI monitoring and promotion of a healthy diet and lifestyle of women before and during pregnancy is needed.

Genetic landscape of the Hvar Island - highlight of a 50-year long bioanthropological research

The paper presents an overview of the 50-year long bioanthropological research of the Hvar islanders and depicts the maternal and paternal genetic landscape of the Hvar population (mtDNA and NRY lineages) in more detail. MtDNA haplogroups were determined in 169 and NRY haplogroups in 407 autochthonous individuals from the Hvar Island. The relatively high level of diversity of mtDNA and NRY lineages has been observed, however with interesting deviations from both the maternal (F1b1 lineage) and paternal (Q2a1a lineage) perspective. Additionally, population substructuring revealed differences between Hvar communities (east-west substructuring), in line with the ethnohistoric background and observed migration patterns on the island. Genetic analysis of the Hvar islanders presents a highlight of the 50-year long anthropological research on this island and offers insight into the current genetic structure of Dalmatia, Croatia, shaped by dynamic and diverse population movements throughout history.

Genetic sub-structuring of Croatian island populations in the Southeastern European context: a meta-analysis

Aim

Methods

Results

Conclusion

Influence of genetic substructuring of statistical forensic parameters on genetic short tandem repeat markers in the populations of Southeastern Europe

Aim

To investigate the influence of specific intrapopulation genetic structures on interpopulation relationships. Special focus was the influence of island population isolation on the substructuring of the Croatian population, and the influence of regional population groups on the substructuring of Southeast European populations.

Methods

Autosomal short tandem repeat (STR) loci were analyzed by using four forensic parameters: matching probability (PM), power of discrimination (PD), power of exclusion (PE), and polymorphic information content (PIC) on a sample of 2877 unrelated participants of both sexes. A sample set comprising 590 participants was analyzed for the first time, and 2287 participants were included from previous studies. The analysis was performed with PowerStats v. 1.2.

Results

The analysis of forensic parameters for all nine loci in the Croatian subpopulations showed the largest deviations in the populations of the islands of Korčula and Hvar. The smallest deviations were found in the mainland population. As for Southeast European populations, the largest deviations were found in the population of North Macedonia, followed by Romania, Albanians from Kosovo, and Montenegro, while the smallest deviations were found in the population of Hungary.

Conclusion

The comparison of forensic parameters between different subpopulations of Croatia and Southeast Europe indicates that the isolation of individual Croatian subpopulations and rare alleles in their gene pool affect the values of forensic parameters. Specific features of (sub)populations should be taken into account for appropriate sampling of the total population when creating a DNA database of STR markers.

Testing the Institute of Medicine (IOM) recommendations on maternal reproductive health and associated neonatal characteristics in a transitional, Mediterranean population

BACKGROUND

High pre-pregnancy body mass index (BMI) and excessive gestational weight gain (GWG) are significant risk factors for maternal and neonatal health.

AIM

To assess pre-pregnancy BMI and GWG during pregnancy and their association with different maternal and neonatal characteristics in the transitional Mediterranean population from the Eastern Adriatic islands.

SUBJECTS AND METHODS

262 mother-child dyads from the CRoatian Islands' Birth Cohort Study (CRIBS) were included in the study. Chi-square test, ANOVA and regression analysis were used to test the association between selected characteristics.

RESULTS

22% of women entered pregnancy with overweight/obesity and 46.6% had excessive GWG. Pre-pregnancy overweight and obesity were significantly associated with elevated triglycerides uric acid levels, and decreased HDL cholesterol in pregnancy. Excessive GWG was associated with elevated fibrinogen and lipoprotein A levels. Women with high pre-pregnancy BMI and GWG values were more likely to give birth to babies that were large for gestational age (LGA), additionally confirmed in the multiple logistic regression model.

CONCLUSION

High maternal pre-pregnancy BMI and excessive GWG were both significantly associated with deviated biochemical parameters and neonatal size. More careful monitoring of maternal nutritional status can lead to better pre- and perinatal maternal health care.

Adherence to Mediterranean Diet and Maternal Lifestyle during Pregnancy: Island-Mainland Differentiation in the CRIBS Birth Cohort

Maternal nutrition and lifestyle in pregnancy are important modifiable factors for both maternal and offspring's health. Although the Mediterranean diet has beneficial effects on health, recent studies have shown low adherence in Europe. This study aimed to assess the Mediterranean diet adherence in 266 pregnant women from Dalmatia, Croatia and to investigate their lifestyle habits and regional differences. Adherence to the Mediterranean diet was assessed through two Mediterranean diet scores. Differences in maternal characteristics (diet, education, income, parity, smoking, pre-pregnancy body mass index (BMI), physical activity, contraception) with regards to location and dietary habits were analyzed using the non-parametric Mann-Whitney U test. The machine learning approach was used to reveal other potential non-linear relationships. The results showed that adherence to the Mediterranean diet was low to moderate among the pregnant women in this study, with no significant mainland-island differences. The highest adherence was observed among wealthier women with generally healthier lifestyle choices. The most significant mainland-island differences were observed for lifestyle and socioeconomic factors (income, education, physical activity). The machine learning approach confirmed the findings of the conventional statistical method. We can conclude that adverse socioeconomic and lifestyle conditions were more pronounced in the island population, which, together with the observed non-Mediterranean dietary pattern, calls for more effective intervention strategies.

MATERNAL GENETIC PROFILE OF SERBIAN AND MONTENEGRIN POPULATIONS FROM SOUTHEASTERN EUROPE

Significant mtDNA variation in Southeastern Europe (SEE) reflects the turbulent and complex demographic history of the region, influenced by gene flow from various parts of Eurasia and a long history of intermixing. In this study we present the maternal genetic profile of the Serbian and Montenegrin populations based on the high resolution analysis of 258 mtDNAs, 119 samples from Serbia and 139 samples from Montenegro. Besides the evidence of minor gene flow from distant central/northeastern Asia, the majority of haplogroups place these populations in the broader genetic landscape of Southeastern Europe, close to their neighbors.

Diversity of Y-chromosomal and mtDNA Markers Included in Mediscope Chip within Two Albanian Subpopulations from Croatia and Kosovo: Preliminary Data

The aim of this preliminary study is to analyze genetic specificity of Kosovo Albanians comparing with neighboring populations using new genetic tool - MEDISCOPE gene chip, to investigate the feasibility of this approach. We collected 37 DNA samples (9 Croats, 17 Albanians from Croatia and 11 Albanians from Kosovo) from unrelated males born in Croatia and Kosovo. Additionally, samples were expanded with female individuals and mtDNA analysis included a total of 61 samples (15 Croats, 23 Albanians from Croatia and 23 Albanians from Kosovo). This pilot study suggests that the usage of the MEDISCOPE chip could be recognized as an efficient tool within recognition of the population genetic specificity even within extremely small sample size.

Genetic heritage of Croatians in the Southeastern European gene pool-Y chromosome analysis of the Croatian continental and Island population

OBJECTIVES

The research objective of this study is to enlarge and deepen the Y chromosome research on the Croatian population and enable additional insights into the population diversity and historic events that shaped the current genetic landscape of Croatia and Southeastern Europe (SEE).

MATERIALS AND METHODS

A high-resolution phylogenetic and phylogeographic analysis of 66 biallelic (SNPs) and 17 microsatellite (STRs) markers of the Y chromosome was performed using 720 Croatian samples. The obtained results were placed in a wider European context by comparison with ∼4450 samples from a number of other European populations.

RESULTS

A high diversity of haplogroups was observed in the overall Croatian sample, and all typical European Y chromosome haplogroups with corresponding clinal patterns were observed. Three distinct genetic signals were identifiable in the Croatian paternal gene pool - I2a1b-M423, R1a1a1b1a*-M558, and E1b1b1a1b1a-V13 haplogroups.

DISCUSSION

The analyses of the dominant and autochthonous I2a1b-M423 lineage (>30%) suggest that SEE had a significant role in the Upper Paleolithic, the R1a1a1b1a*-M558 lineage (19%) represents a signal from present day Slavic populations of Central Europe in the Croatian population, and the phylogeography of the E1b1b1a1b1a-V13 clade (around 9%) implies cultural diffusion of agriculture into Europe via the Balkan Peninsula. Am. J. Hum. Biol., 2016. © 2016 Wiley Periodicals, Inc. Am. J. Hum. Biol. 28:837-845, 2016. © 2016Wiley Periodicals, Inc.

Maternal genetic heritage of Southeastern Europe reveals a new Croatian isolate and a novel, local sub-branching in the x2 haplogroup

High mtDNA variation in Southeastern Europe (SEE) is a reflection of the turbulent and complex demographic history of this area, influenced by gene flow from various parts of Eurasia and a long history of intermixing. Our results of 1035 samples (488 from Croatia, 239 from Bosnia and 130 from Herzegovina, reported earlier, and 97 Slovenians and 81 individuals from Žumberak, reported here for the first time) show that the SEE maternal genetic diversity fits within a broader European maternal genetic landscape. The study also shows that the population of Žumberak, located in the continental part of Croatia, developed some unique mtDNA haplotypes and elevated haplogroup frequencies due to distinctive demographic history and can be considered a moderate genetic isolate. We also report seven samples from the Bosnian population and one Herzegovinian sample designated as X2* individuals that could not be assigned to any of its sublineages (X2a'o) according to the existing X2 phylogeny. In an attempt to clarify the phylogeny of our X2 samples, their mitochondrial DNA has been completely sequenced. We suppose that these lineages are signs of local microdifferentiation processes that occurred in the recent demographic past in this area and could possibly be marked as SEE-specific X2 sublineages.

Influence of evolutionary forces and demographic processes on the genetic structure of three Croatian populations: a maternal perspective

BACKGROUND

Many Croatian islands are examples of genetic isolates, with low level of heterozygosity and high level of inbreeding, due to practice of endogamy.

AIM

The aim was to study the genetic structure of two insular and one mainland population through high-resolution phylogenetic analysis of mitochondrial DNA (mtDNA).

SUBJECTS AND METHODS

MtDNA polymorphisms were explored in 300 unrelated individuals from Mljet, Lastovo and the coastal city of Dubrovnik, based on SNP polymorphisms.

RESULTS

All mtDNA haplogroups found in the sample were of typical European origin. However, the frequency distribution of their subclades differed significantly from other Croatian and European populations. MtDNA haplotype analysis revealed only two possible founder lineages on Mljet and six on Lastovo, accounting for almost half of the sample on both islands. The island of Mljet also has the lowest reported haplotype and nucleotide diversity among Croatian isolates and the island of Lastovo, a new sublineage of a usually quite rare U1b clade.

CONCLUSION

The results can be explained by the effect evolutionary forces have on genetic structure, which is in line with the specific demographic histories of the islands. An additional research value of these two island isolates is the appearance of certain Mendelian disorders, highlighting their importance in epidemiological studies.