OBJECTIVE: Hereditary dentin defects can be grouped into three types of dentinogenesis imperfecta (DGI) and two types of dentin dysplasia. Tooth enamel is considered normal in patients with hereditary dentin defects, but is easily worn down and fractured due to DSPP mutation-induced altered dentin properties. The purposes of this study were to identify genetic cause of a family with type II DGI and enamel defects. MATERIALS AND METHODS: We identified a family with type II DGI and a unique form of hypoplastic enamel defect affecting occlusal third of the crown. Family members were recruited for the genetic analysis and DNA was obtained from peripheral whole blood. RESULTS: Mutational analysis revealed a T to A transversion in exon 3 of the DSPP (c.53T>A, p.V18D). Haplotype analysis showed that the same mutation arose separately in two different families having DGI with similar enamel defects, indicating that this phenotype is associated with this specific DSPP mutation. Clinical features suggest that enamel formation was affected in the affected individuals during early amelogenesis, in addition to the dentin defect. CONCLUSIONS: We observed that a DSPP gene mutation not only influences dentinogenesis but also affects early stage amelogenesis.