Progressive pseudorheumatoid dysplasia, an autosomal-recessive skeletal disorder, involves the dysregulation of both BMP and Wnt/β-catenin signaling pathways.477 Robinow syndrome (RS), caused by loss-of-function mutations in ROR2, is characterized by reduced phosphorylation of Smad1/5/8.478 Fragile X syndrome (FXS), which results from FMR1 silencing, exhibits enhanced BMPRII signaling, suggesting that the BMPRII-LIMK1 axis is a therapeutic target for FXS and related autism spectrum disorders.479. Here, SMAD1 is linked to fragile X syndrome.