Since the features associated with the Dlx3 deletion were shown to be due to down-regulation of dentin sialophosphoprotein (Dspp), they appear to rather phenocopy the so-called shell teeth observed in dentinogenesis imperfecta type III (OMIM#125500) which is caused by mutations in the DSPP gene (MacDougall et al., 2006; Kim and Simmer, 2007). This evidence concerns the gene DSPP and dentinogenesis imperfecta type 3.