Population-Based Genetic Assessment of Thrombophilia Polymorphisms: Allelic Frequencies and Population Linkage Dynamics

<i>Background and Objectives</i>: Thrombophilia is a prothrombotic disorder that increases the risk of blood clotting and can pose serious health problems. It is considered a condition of gene-gene or gene-environment interactions. Variation in the prevalence of thrombophilia mutations and their interaction among populations necessitates localized genetic assessments. However, population-based genetic data remains limited for developing effective preventive strategies. <i>Materials and Methods</i>: This cross-sectional observational study was conducted over five years (2020-2024) at a tertiary university hospital in Northern Greece. A total of 2961 individuals aged 18-85 years (mean: 50.5) were registered based on family or medical history of venous thromboembolism (VTE) or clinical symptoms of VTE. The final analysis included 2078 participants comprising 1143 males (55%) and 935 females (45%), who met all the inclusion criteria. Inclusion criteria were absence of acute illness or malignancy, informed consent, and an adequate DNA quantity for genotyping, whereas excluded criteria included incomplete laboratory data, active inflammatory or malignant disease, and cognitive or psychiatric conditions. Peripheral blood samples were collected in 2 mL K₃-EDTA tubes, and genomic DNA was analyzed using real-time polymerase chain reaction (PCR) with melting curve analysis and hybridization probes (LightMix^® in vitro diagnostics, TIB MolBiol, Berlin, Germany). Five thrombophilia-related polymorphisms, Factor V Leiden (<i>F5</i> G1691A), prothrombin (<i>F2</i> G20210A), methylenetetrahydrofolate reductase (<i>MTHFR</i> C677T and <i>MTHFR</i> A1298C), and Plasminogen Activator Inhibitor-1 (<i>PAI-1</i>) 4G/5G, were examined for allele and genotype frequencies, Hardy-Weinberg equilibrium testing, pairwise linkage disequilibrium (D' and r²), and power analysis. For subjects tested for Factor V Leiden (<i>n</i> = 1476), the activated protein C resistance (APC) ratio was additionally evaluated using the ACL TOP 750 analyzer. <i>Results</i>: Allele frequencies were 7.3% for FV Leiden and 3.7% for <i>FII</i>. The <i>PAI-1</i> allele was distributed at 44%, while the <i>MTHFR</i> (C677T and A1298C) alleles were each present at 33%. Significant linkage disequilibrium was identified between <i>MTHFR</i> (C677T and A1298C) and between <i>MTHFR</i> A1298C and <i>PAI-1</i>. No evolutionary pressure or demographic bias was found in the Hardy-Weinberg equilibrium. The APC ratio demonstrated a high sensitivity (99.2%) and specificity (96.6%), indicating that it may serve as a reliable screening method. <i>Conclusions</i>: Our findings highlight informative patterns in the genetic predisposition to thrombophilia, which may help develop rule-based strategies for implementing thromboprophylaxis guidelines and personalized medical interventions.