EN
Dwarfism is a frequently occurring congenital disorder in human and farm animals. Defects in endochondral ossification lead to disproportionate dwarfism with abnormal length of the limbs in relation to the size of the trunk. Based on observed skeleton abnormities in general, a short- and long-limbed achondroplasia can be recognized. Short-headed dwarfism often relates to the latter ACH form and comprises a number of head deformities with a characteristic craniofacial shortening. Lethal cases with severe skeleton malformations occur when ACH is inherited in the homozygous recessive mode. A number of different ACH forms were described in Dexter, Holstein Fresian, Jersey, Aberdeen Angus, Hereford, Shorthorn and Japanese brown cattle. Only in the last mentioned breed two causative mutations have been detected causing ACH phenotype in the appendicular skeleton. Extensive efforts are being made to find mutations determining achondroplasia in other cattle breeds.