Genetic polymorphisms of serotonin transporter and receptor 1A could influence success during embryo implantation and maintenance of pregnancy.

OBJECTIVE: To explore whether serotonin-related gene polymorphisms influence clinical outcomes of IVF treatment in recipients using donated oocytes.
DESIGN: Nested case-control study.
SETTING: University-affiliated infertility clinic. PATIENT(S): Two hundred forty-five women undergoing IVF treatment with donated oocytes. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Genotype and haplotype analysis of the serotonin transporter-linked polymorphic region (5-HTTLPR), rs1800532, rs6295, rs6313, and rs3813929, between recipients grouped according to the results of the oocyte donation for IVF treatment. RESULT(S): No differences were found between genotype distribution of the tryptophan hydroxylase 1, serotonin receptor 2A, and serotonin receptor 2C polymorphisms. Recipients carrying the LL genotype for 5-HTTLPR had lower clinical pregnancy rates (PR) and higher biochemical pregnancy loss (BPL) events. Lower implantation rates were found in CC carriers for 5-HT1A.rs6295 who also presented higher BPL rates. A lower incidence of clinical pregnancy was observed for LC haplotypes, corresponding to an increase in BPL rates. CONCLUSION(S): A strong association was found between early pregnancy loss and recipients carrying the 5-HTTLPR and rs6295 genetic variants. Identifying biological processes involving serotonin and embryo implantation may help to understand the dynamics of the maternal-embryo dialogue.