Aim: to investigate the frequency of gene polymorphisms related to coagulation, the folate cycle, platelet receptors, serine protease inhibitor clade E member 1 (SERPINE1), selectin P ligand (SELPLG), and Janus kinase 2 (JAK2) in patients with pediatric-onset portal vein thrombosis (PVT).

Materials and methods. A cross-sectional study was conducted, including patients with pediatric-onset non-cirrhotic PVT (n = 31), all of European ancestry. Polymerase chain reaction was used to genotype the following polymorphisms: F2 (rs1799963), F5 (rs6025), FGB (fibrinogen beta chain) (rs1800790), ITGA2 (integrin subunit alpha 2) (rs1126643), ITGB3 (integrin subunit beta 3) (rs5918), MTHFR (methylenetetrahydrofolate reductase) (rs1801133), SERPINE1 (rs1799889), SELPLG (rs2228315), and JAK2 (rs77375493). A history of local risk factors for PVT in the early neonatal period was noted in 12 (39 %) patients, including omphalitis, umbilical sepsis, and umbilical vein catheterization.

Results. Mutations in the F2 (rs1799963) and F5 (rs6025) genes were identified in two patients. The A allele of the FGB gene (rs1800790) was found with a frequency of 21 %, the T allele of the ITGA2 gene (rs1126643) with a frequency of 37.1 %, and the T allele of the MTHFR gene (rs1801133) with a frequency of 32.3 %. The 4G polymorphism in the SERPINE1 gene (rs1799889) was the most frequent: it was found in the homozygous form in 18 (58 %) patients and in the heterozygous form in 9 (29 %) patients; the frequency of the 4G allele was 72.6 %. The somatic JAK2 mutation (rs77375493) was not detected in any of the patients. The presence of either a mutation in the F2 or F5 genes, or homozygous variants for the other studied polymorphisms, was identified in 24 (77 %) patients. A single genetic risk factor was present in 15 (48 %) patients, two factors — in 6 (19 %) patients, and three factors — in 3 (10 %) patients. No significant differences in the frequency of individual polymorphisms were found between patients with and without local risk factors. However, the combination of the A allele of the FGB gene and the C allele of the ITGB3 gene was observed significantly more frequently in patients with local risk factors compared to those without (33 % vs. 5 %; p = 0.039).

Conclusion. In a small Russian cohort of patients with pediatric-onset PVT, well-known thrombophilic mutations in the F2 and F5 genes were identified. Also, polymorphisms in SERPINE1, MTHFR, FGB, ITGA2, ITGB3, and SELPLG genes were identified, which potentially contribute to an increased risk of thrombosis.