Further studies revealed that mice with a pure mutation in Pkd1 showed spina bifida, osteoarticular dysplasia, and a pronounced delay in the processes of endochondral and intramembranous ossification at both embryonic and neonatal stages, suggesting that the deletion of Pkd1 had a severe impact on skeletal development (Lu et al., 2001). Here, PKD1 is linked to spina bifida.