A de novo germline mutation of DLX 3 in a Brown Swiss calf with tricho‐dento‐osseus‐like syndrome

Objective A novel congenital disorder affecting a calf was observed, and its phenotype and genetic mutation identified. Animal A six‐month‐old female Brown Swiss calf. Methods Diagnostic investigation and whole genome sequencing of a case parent trio was performed. Results The calf had a dull kinky coat with mild hypotrichosis, and teeth with brown staining and enamel defects. Histological examination of skin biopsies was compatible with a follicular dysplasia. Radiography and computed tomography revealed thickening of the skull bones and large pulp cavities with a marked thinning of enamel affecting all teeth. A de novo germline mutation affecting the distal‐less homeobox gene ( DLX 3 ) was identified. The 10 bp frameshift mutation in exon 3 of the bovine DLX 3 gene is predicted to replace the second C‐terminal transactivation domain of the wild‐type protein by a recoded peptide of 99 amino acids without any sequence similarity. Conclusion and clinical importance A causative mutation for a sporadic phenotype resembling human tricho‐dento‐osseous syndrome was identified after detection of a de novo germline mutation in the DLX 3 gene.