DLX3 and tricho-dento-osseous syndrome: Tricho-dento-osseous syndrome (Online Mendelian Inheritance in Man (OMIM):#190320; TDO) is an exceedingly rare autosomal dominant, completely penetrant genetic condition caused by heterozygous pathogenic variants in the distal-less homeobox 3 (DLX3) gene (OMIM:∗600525), which encodes a transcription factor crucial in fetal limb development.1