RESUMO
OBJECTIVES: To outline the possible role of the imprinted genes in early human embryogenesis and implantation. DATA IDENTIFICATION: Literature review. STUDY SELECTION: Studies examining the issues of genomic imprinting, implantation, gestational trophoblastic diseases, placental gene expression, and trophoblast invasion. RESULTS: Certain genes have been shown to be expressed either in the embryo or in the uterine decidua before implantation. Some of these have been shown to be parentally imprinted, that is, expressed either from their paternal or maternal origin. The paternally expressed genes are linked to placental proliferation and invasiveness. CONCLUSIONS: Clinical and basic data from different disciplines indicate that genomic imprinting may be crucial to the process of implantation.
