In our previous studies, we reported the association of single nucleotide polymorphisms (SNPs) spanning the DYX1C1, DCDC2, KIAA0319, ROBO1, and GRIN2B genes with DD and DD-related quantitative traits in Italian nuclear families with DD [12,13,14,15,16,17,18]. This evidence concerns the gene KIAA0319 and dentin dysplasia.