KLK4 and tricho-dento-osseous syndrome: Combined with the hypoplasia and hypomaturation types of amelogenesis imperfecta detected in TDO patients [3], we suggested that mutant DLX3 disrupts both the apposition and mineralization processes of amelogenesis through inhibiting the activation function of wild-type DLX3 on Enam, Amelx, Klk4, and Odam. DLX3 staining was also observed in odontoblasts, consistent with the regulation of Dspp (dentin sialophosphoprotein), one of the main dentin matrix protein genes, by DLX3 [16].