# Uncovering the Genetic Structure of the Sekler Population in Transylvania Through Genome-Wide Autosomal Data

## TL;DR

This study uses genetic data to show that the Sekler population in Transylvania is genetically similar to Hungarians, with only minor differences in a few villages.

## Contribution

The study provides the first genome-wide analysis of the Sekler population, revealing their genetic coherence and minor localized drift.

## Key findings

- Sekler groups form a single genetic cluster with Hungarians, showing no major genetic differences.
- Two Sekler villages show signs of increased relatedness and subtle separation, suggesting local demographic drift.
- The Sekler population is genetically cohesive, shaped by shared historical and linguistic ties.

## Abstract

Background/Objectives: The Seklers are a Hungarian-speaking regional population in Transylvania, Romania, with a long and complex history, yet comprehensive genome-wide studies remain limited. Our aim was to characterize the genetic background of multiple Sekler communities using high-density autosomal data and to place them in a broader Central and Eastern European context. Methods: Here we analyzed genome-wide autosomal SNP data obtained from 17 Sekler groups. Allele frequency- and haplotype-based approaches were applied to assess overall genetic structure, ancestry patterns, recent shared ancestry, and signals of demographic history. Results: Analyses based on overall allele-frequency patterns showed that Sekler groups fit into a single, coherent genetic cluster shared with Hungarians. No major differences were detected among the Sekler communities at this broader genomic level, and their genetic profiles were largely indistinguishable from one another. Using haplotype-based methods, most Sekler groups again formed a compact cluster. However, two villages, Deményháza and Nyárádszentimre, showed clear signs of increased within-group relatedness and subtle separation. These patterns might indicate that both communities experienced stronger local drift and reduced effective population size, while other Sekler groups showed no comparable deviation from the general regional pattern. Conclusions: Although a small number of villages display modest signs of localized demographic drift, our results support that the Seklers represent a regionally distinct and internally cohesive population, whose genetic structure is shaped mainly by common historical and linguistic ties, with minor village-level variation, forming a uniform part of the Hungarian-speaking population of the East-Central European region.