Publication date: Jul 01, 2026
The clinical relevance of inherited thrombophilia-related polymorphisms in COVID-19 remains uncertain. This study investigated the distribution of Factor V Leiden (FVL) G1691A and MTHFR A1298C polymorphisms in patients with COVID-19 and associations with laboratory findings and short-term mortality. This case-control study included 150 patients with PCR-confirmed COVID-19 and 300 controls. Genomic DNA was isolated from peripheral blood, and FVL G1691A and MTHFR A1298C polymorphisms were analyzed. Associations with d-dimer levels, hospitalization duration, and 30- and 90-day mortality were evaluated using multivariable linear and Cox regression analyses. The FVL GG genotype was less frequent in patients than controls (77. 3% vs. 87. 0%, p = 0. 009), whereas the MTHFR AA genotype was more frequent (76. 7% vs. 61. 3%, p = 0. 001). Heterozygosity in both genes did not differ between groups (8. 0% vs. 6. 3%, p = 0. 552). Patients with heterozygosity in both genes had higher d-dimer levels (median 435. 0 vs. 201. 0 ng/mL, p = 0. 024) and longer hospitalization (median 7. 5 vs. 5. 0 days, p = 0. 037). After adjustment, heterozygosity in both genes remained associated with higher log-transformed d-dimer levels (β = 0. 758, 95% CI: 0. 239-1. 277; p = 0. 005), as did MTHFR A1298C (β = 0. 432, 95% CI: 0. 007-0. 856; p = 0. 046). None of the polymorphisms was associated with 30- or 90-day mortality, while age independently predicted both outcomes. Thrombophilia-related polymorphisms may influence d-dimer levels and hospitalization duration in COVID-19 but do not appear to affect short-term mortality.