Genetic variation at 15 polymorphic, autosomal, short tandem repeat loci of two Hungarian populations in Transylvania, Romania

Aim

To determine allele distribution and genetic parameters for two populations living in the Romanian region of Transylvania: Hungarians from Cluj and Szeklers from Covasna county, and to compare the results between the two populations and with other Hungarian and Romanian populations.

Methods

Allele frequencies for 15 autosomal STR loci (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, VWA, TPOX, D18S51, D5S818, and FGA), several forensic parameters, and paternity parameters were determined for Szekler Hungarians of Covasna county (CV-Sze, n = 278) and non-Szekler Transylvanian Hungarians, who were represented by Hungarians from Cluj county (CJ-Hu, n = 146).

Results

Average expected heterozygosity was above 70%. The combined power of discrimination and combined power of exclusion values were high. All tested loci were in agreement with Hardy-Weinberg equilibrium, with the exception of the CSF1PO locus for Covasna county. Pairwise population comparison tests and exact population differentiation tests showed no significant differences between the CJ-Hu and CV-Sze populations, and the CV-Sze group showed greater differences from other Romanian populations than did the CJ-Hu group.

Conclusion

Hungarians from Cluj show greater genetic heterogeneity than Szeklers from Covasna. The loci tested are suitable for studying micro-differentiation between these two populations, and between these populations and other populations in Hungary and Romania.Since its introduction 25 years ago, DNA fingerprint analysis has become a major tool in diagnosing and treating disease, forensic identification, taxonomy, phylogenetics, and other applications (1,2). Microsatellites, also called simple sequence repeats or short tandem repeats (STR), are among the most polymorphic DNA markers. These sequences of 2-6 basepairs are easily amplified by polymerase chain reaction (PCR) and show widespread and uniform distribution throughout the genome. They show a high level of polymorphism, which is relatively stable (3). These properties of STR loci make them suitable for numerous genetic, forensic, and medical applications.According to the 2002 census in Romania (4), 19.6% of the residents of the Transylvania region belong to the Hungarian ethnic group, with most of them living in the Szekler (Székely) counties of Covasna and Harghita. Earlier genetic studies have suggested that ancient Hungarians and Szekler Hungarians separated from each other more than 1000 years ago. Some centuries ago, the two Szekler groups separated from each other, which affected the genetic structure of these groups (5). In the last decade, genetic parameters for the Szekler population (HR-Sze) and Csángó population (HR-Csn) from Harghita have been published (6), but no population study has been conducted on Szekler communities from Covasna and other, non-Szekler Hungarians, from Transylvania.This study sheds light on the genetic makeup of Hungarian communities from Transylvania by determining CODIS STR allele frequencies, as well as forensic and paternity data for the Szekler Hungarians of Covasna county (CV-Sze) and non-Szekler Hungarians of Cluj county (CJ-Hu).Using allele frequencies, we carried out pairwise comparisons and differentiation tests to test the following hypotheses:1. There is significant genetic distance between the non-Szekler Hungarians (CJ-Hu) and the Szekler populations (HR-Sze and CV-Sze), which indicates genetic isolation of the two Szekler groups from the other Hungarian communities living in Transylvania.2. There is significant genetic distance between the two Szekler populations (HR-Sze and CV-Sze), which reveals genetic isolation of the Szekler communities.3. There is a positive correlation between geographical distance and genetic distance when ethnic Hungarian populations in this study are compared with other ethnic Romanian populations.4. As a result of population migration and ethnic cross-breeding, non-Szekler Hungarians in this study show greater genetic heterogeneity than do Szekler Hungarians.