This was the first report of a mutation within the homeodomain of DLX3 compared to previous studies that have shown a DLX3 mutation outside the homeodomain associated with TDO; the authors concluded that TDO and some forms of AI-Type IV variant are allelic and suggested that this new DLX3 mutation affects the formation of enamel and teeth but lacks the defects of bone and hair. This evidence concerns the gene DLX3 and tricho-dento-osseous syndrome.