Preeclampsia has a familial component suggesting that one or more common alleles may act as susceptibility genes. Some families may have "private" predisposing mutations. The central role of the placenta in the pathogenesis of preeclampsia implies that fetal genes contribute to the disease process. Twin studies support the role of maternal and fetal gene interaction. Candidate gene studies have not yielded consistent results. Genome-wide linkage studies provide powerful means to study disease susceptibility genes, and several loci have been mapped. Parent-of-origin effect of the STOX1 gene has been suggested on chromosome 10q22 locus in the Dutch population. Maternally inherited missense mutations in the STOX1 gene of the fetus have been shown to co-segregate with the maternal preeclamptic phenotype. Up-regulation of placental leptin expression has been found in several studies and might be of importance in the pathogenesis of preeclampsia. DNA microarray is ideal tool for screening gene expression in preeclamptic tissues, but critical attitude is needed when interpreting the results. The placental DNA and mRNA in maternal plasma hold great promise as novel biomarkers for the prediction of preeclampsia. Finding genes prediposing to preeclampsia will enhance our understanding of the disease mechanism, and might allow identification of prognostic and therapeutic subgroups.