RELN and progressive pseudorheumatoid arthropathy of childhood: During the post-partum period, estrogen levels decrease significantly and might contribute to the development of PPD (Hedges et al., 2021) and while estrogen can influence the reelin system and vice versa (Bender et al., 2010; Meseke et al., 2018) whether alterations in reelin occur during the critical post-partum phase and could be a vulnerability factor remains unexplored.