Genetic basis for Chondrodysplasia in Norwegian Elkhounds - it is an autosomal recessive inherited skeletal disorder caused by a nonsense mutation in the ITGA10 gene. The ITGA10 gene encodes the integrin alpha-10 subunit, a protein that forms a collagen-binding α10β1 receptor expressed specifically in cartilage chondrocytes. This receptor mediates chondrocyte interaction with the extracellular matrix during endochondral ossification, the process by which cartilage is replaced by bone in developing long bones. Affected dogs inherit two copies of this pathogenic variant; carriers have one copy and show no clinical signs but can pass the mutation to offspring. Genetic testing is available for breeders to identify carriers and affected dogs.
Pathophysiolgy - The premature stop codon in ITGA10 causes the integrin α10 protein to be truncated and absent in cartilage tissue, disrupting the formation and function of the α10β1 collagen receptor. This receptor is essential for normal cartilage development and bone growth within the growth plates of long bones. The lack of functional α10β1 integrin impairs chondrocyte-matrix interactions, resulting in abnormal cartilage synthesis and defective endochondral ossification, leading to irregular bone growth and structural bone abnormalities. This manifests as disproportionate dwarfism, characterized by markedly short limbs and skeletal deformities.
Complications - Affected Norwegian Elkhounds display disproportionate dwarfism with significantly shortened limbs, around 10 cm shorter than normal for adults. Abnormal skeletal conformation such as bowed front legs, “knock-knee” deformity, and shortening of outer digits. Other skeletal abnormalities including hip dysplasia and muscle atrophy, especially in the hind limbs. Predisposition to joint problems and arthritis later in life due to abnormal bone and joint alignment. Radiographic signs of skeletal dysplasia can be detected by 5 to 12 weeks of age, with clinical signs typically evident from late puppyhood.
Why This Matters to Breeders and Vets
Breeders: Because ITGA10-related chondrodysplasia is recessively inherited, mating two carriers carries a 25% risk of producing affected puppies. DNA screening for the ITGA10 mutation is crucial to avoid propagating the disease within Norwegian Elkhound populations while maintaining genetic diversity.
Veterinary Role: Early clinical recognition based on limb conformation and radiographs allows for diagnosis, with genetic confirmation possible through testing. Vets should counsel owners on the potential for long-term orthopedic complications such as arthritis and recommend appropriate management strategies including joint health preservation and monitoring.
Management: While no cure exists, symptomatic treatment focuses on maintaining mobility, controlling pain associated with arthritis, and preventing secondary musculoskeletal issues.
Summary - Chondrodysplasia ITGA10 (Elkhound Type) is an autosomal recessive genetic disorder caused by a nonsense mutation in the ITGA10 gene. It leads to defective cartilage development and abnormal bone growth, manifesting as disproportionate short-limbed dwarfism with skeletal abnormalities including bowed legs and joint malformations. Affected dogs are predisposed to arthritis and muscle atrophy later in life. Genetic testing enables breeders and veterinarians to detect carriers and affected dogs early, supporting informed breeding decisions and clinical management. This condition highlights the critical role of the integrin α10β1 collagen receptor in normal canine skeletal development.