Preliminary pathological results on chondrodysplastic dwarfism in Tyrolean Grey cattle due to deletion in the EVC2 gene

Preliminary pathological results on chondrodysplastic dwarfism in Tyrolean Grey cattle due to deletion in the EVC2 gene C Benazzi*, KE Dittmer†, KG Thompson†, C Drögemüller‡, A Gentile*, LV Muscatello*, L Murgiano‡, C Piffer#, M Bolcato* and B Brunetti* *Department of Veterinary Medical Sciences, University of Bologna, 40064 Ozzano dell’Emilia, Italy. Email: cinzia.benazzi@unibo.it †Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand ‡Institute of Genetics, Vetsuisse Faculty, University of Bern, 3001 Bern, Switzerland. #Gesundheitbezirk Bozen, Laura Conti Strasse 4, 39100 Bozen, Italy. During July–November 2013 breeders reported the birth of Italian Tyrolean Grey calves with abnormally short limbs. Seven calves, aged 2–5 months, were referred to the Department of Veterinary Medical Sciences, Bologna, Italy. Whole genome resequencing of an affected calf detected a single candidate causal mutation in the Ellis van Creveld syndrome 2 (EVC2) gene. All animals had difficulties in assuming or maintaining a quadrupedal stance, with deterioration in this ability with increased growth. The limbs were disproportionately short and bulky, variably rotated and arched in a dumbbell-like position. At necropsy, the limbs (in particular the femur and humerus) were rotated and significantly shortened. Histologically the growth plates of long bones and vertebrae were irregular and prematurely closed. The reserve zone showed variable thickness at the expense of proliferative and hypertrophic zones, which were disorganised with multifocal loss of the normal columnar arrangement. In one calf reduced development of the heart valves was noted. In three female calves the genital tracts appeared fully mature, with numerous follicle-like structures on the ovaries. The uteri had multiple polypoid structures.