The treatment of pre-eclampsia is based on the prevention and the symptoms' management, therefore screening of risk patients and early diagnosis of the developing preeclampsia are essential for reduction of the risk of the negative effects on the mother and fetus. A significantly higher incidence of preeclampsia was observed in women after in vitro fertilization. During preeclampsia, ERVW-1 expression and production of syncytin-1 (one of the main regulators of processes during the trophoblast formation and differentiation) are changed. The abnormalities of trophoblast are typical characteristics of pre-eclamptic placentas. The aim of the project is to characterize the genetic variability of ERVW-1 in order to find a link between genetic variants and changes in expression of this gene, or between the types and complications of preeclampsia in patients after natural and in vitro fertilization. Identifying such DNA variants would widen and refine the diagnostic possibilities of preeclampsia. It would also contribute to clarifying the role of syncytin-1 during pregnancy and its importance in development of the placenta pathological conditions to which preeclampsia belongs.