Genetic and <i>in silico</i> analysis show a role of <i>SMAD3</i> on recurrent pregnancy loss

Recurrent pregnancy loss (RPL) is one of the most common reproductive failures affecting 1–5% of couples. Smad3 is an effector of signalling of the Transforming Growth Factors-β superfamily (TGF-β), regulating the transcription of several target genes of these cytokines. The objective of this study was to evaluate the influence of a variant on <i>SMAD3</i> (rs17293443) in RPL. A case-control study was carried out with 149 women who experienced RPL and 159 controls, as well as bioinformatics tools to determine the role of this variant in this condition. Our study showed an allelic (<i>p</i> = 0.023) and genotypic (<i>p</i> &lt; 0.01) association of this variant with the RPL. Our functional <i>in silico</i> predictions suggest that this variant causes a change in <i>SMAD3</i> expression levels. Alterations in the expression of this gene can directly compromise the Smad3-dependent signalling pathway that is fundamental for key processes for gestation such as steroid hormone regulation and implantation, as demonstrated by ontologies analyses performed and the literature. Our findings regarding the involvement of Smad3 on RPL are a novelty in this field, and they seem to be promising to the clinical management of this condition.