Genes in the AKT (POSTN, RACK1, VCP) and β-catenin and Wnt signalling pathways (CTNNB1, WNT2, WNT4, RSPO2, SFRP1, SFRP4, ZIC1) have also been implicated in DD [41], [42]. Here, SFRP4 is linked to dentin dysplasia.