Professor Hannes Lohi’s research group at the University of Helsinki and Folkhälsan Research Center in Finland has identified a mutation in the ITGA10 gene that causes chondrodysplasia (dwarfism) in two dog breeds, the Norwegian Elkhound and the Karelian Bear Dog. The research revealed a new chondrodysplasia gene in dogs, and a candidate gene for human chondrodysplasias. The finding has implications on bone biology as well as canine health. A genetic test can now be used to identify mutation carriers in the two affected dog breeds. The study was published online in the open-access journal PLOS ONE on 25 September 2013. The ITGA10 mutation causes autosomal recessive disproportionate short-stature dwarfism of varying severity. The appearance of affected dogs is characterized by considerably shorter limbs than normal dogs, and other skeletal abnormalities may follow, including bowed forearms, abnormal digits, and malformed femoral heads. The ITGA10 gene codes for an integrin subunit that assembles into a cartilage-specific collagen receptor, found in the growth plates of long bones. The receptor is important for the process of endochondral ossification, in which the cartilage cells first proliferate, and are then replaced by bone tissue. Accordingly, several abnormalities have been found in the growth plates of affected dogs both in radiographic and histological examinations. The causative mutation was mapped to a specific region on canine chromosome 17 by comparing the genomes of affected and healthy dogs. Further analysis of this chromosomal region revealed a single nucleotide change in the ITGA10 gene, which disrupts the gene by introducing a signal that prematurely ends the production of the encoded integrin subunit.
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