Hereditary Vitamin D-Resistant Rickets Type II
Affected Genes: VDR
Inheritance: Autosomal Recessive
Variant(canFam6):
chr27:39412048-39412049 1 bp deletion C
General Information: Hereditary Vitamin D-Resistant Rickets Type II (HVDRR-II) is an inherited disorder in dogs where a genetic mutation affects the body’s ability to respond to vitamin D, leading to impaired calcium and phosphorus balance. Dogs with two copies of the associated gene mutation are predisposed to HVDRR-II, which typically manifests in early life. Symptoms include bone deformities, muscle weakness, growth retardation, and skeletal pain. Affected dogs may display difficulty in walking, lameness, and a characteristic bowed appearance of the limbs. The condition can lead to severe skeletal issues and impact the overall quality of life. Early diagnosis and management through dietary adjustments and supplements are crucial to mitigate the symptoms and improve bone health in affected dogs.
How to Read Your Dog's Test Results for this Genetic Variant:
Two Variants Detected: Dog Likely Affected
One Variant Detected: Dog Unlikely Affected
No Variants Detected: No Effect
Gene / Testing Information: Genetic testing of the specific gene associated with Hereditary Vitamin D-Resistant Rickets Type II can determine if a dog is a carrier of this condition. HVDRR-II is inherited in an Autosomal Recessive manner, meaning that dogs must inherit two copies of the mutated gene, one from each parent, to develop the disease. Carrier dogs, possessing only one copy of the mutation, typically do not show symptoms but can pass the gene to their offspring. When two carriers are bred, each pup has a 25% chance of developing the disease and a 50% chance of being a carrier. Reliable genetic testing is crucial for informed breeding practices to eliminate this mutation from breeding lines, and breeding two carriers together is not recommended to avoid producing affected pups. Dogs that are not carriers have no increased risk of having affected offspring.
References:
LeVine DN, Zhou Y, Ghiloni RJ, Fields EL, Birkenheuer AJ, Gookin JL, Roberston ID, Malloy PJ, and Feldman D. Hereditary 1,25-Dihydroxyvitamin D-Resistant Rickets in aP ome ranian Dog Caus ed by a N ove l Mutati on i n the V itamin DReceptor Gene. J Vet Intern Med. 2009 23:1278–1283