BackgroundTricho-dento-osseous (TDO) syndrome is an autosomal dominant disorder characterized by anomalies in hair, teeth and bone (OMIM190320). Various mutations of Distal-Less 3 (DLX3) gene are found to be responsible for human TDO. The aim of this study was to investigate effects ofDLX3on tooth and bone development using a zebrafish model.MethodsThedlx3bmutant zebrafish lines were established using the gene targeting tool transcription activator-like effector nuclease (TALEN). Micro-computed tomography was used to render the three-dimensional skeletal structures of mutant fishes. The pharyngeal bone along with connected teeth was isolated and stained by Alizarine Red S, then observed under stereomicroscope. Scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) were used to examine the tooth surface morphology and mineral composition. Quantitative real-time PCR was used to analyze gene expression.ResultsA moderate curvature of the spine toward the dorsal side was found at the early larval stages, appearing in 86 out of 100 larvae indlx3b-/-group as compared to 3 out of 99 in thedlx3b+/+group. At the adult stage, three of the thirtydlx3b-/-homozygotes exhibited prominent abnormal curvature in the spine. SEM revealed morphological surface changes in pharyngeal teeth enameloid, accompanied by a decrease in the mineral content detected by EDS. Furthermore, specific secretory calcium-binding phosphoprotein (SCPP) genes, includingodam,scpp9,spp1,scpp1, andscpp5were significantly downregulated indlx3bmutants.ConclusionThe findings of this study suggest thatdlx3bis critical for enamel mineralization and bone formation in zebrafish. Moreover, the discovery of the downregulation of SCPP genes indlx3bmutants sheds new light on the molecular mechanisms underlying TDO syndrome.