A de novo germline mutation of DLX3 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 (DLX3) was identified. The 10 bp frameshift mutation in exon 3 of the bovine DLX3 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 DLX3 gene.