Common Symptoms
Diffuse cystic renal dysplasia and hepatic fibrosis is an inherited developmental disease of the Norwich terrier. Affected dogs are born with abnormalities or complete absence of hair-like structures called cilia which play an important role in organ development and other developmental processes. Lack of functional cilia in affected dogs results in severe malformation of the kidneys and scarring (fibrosis) of the liver during fetal development. Kidneys of affected dogs are typically enlarged due to formation of large cysts throughout the tissue. In addition, affected dogs are often born with poorly developed lungs and may also display a cleft palate, free fluid in the chest or abdominal cavity, or malformations of the diaphragm. Affected puppies typically die within a few days of birth.
Breed-Specific Information for the Norwich Terrier
The Mutation of the INPP5E gene associated with Diffuse Cystic Renal Dysplasia and Hepatic Fibrosis has been identified in the Norwich terrier, although its overall frequency in this breed is unknown.
Testing Tips
Genetic testing of the INPP5E gene in the Norwich terrier will reliably determine whether a dog is a genetic Carrier of diffuse cystic renal dysplasia and hepatic fibrosis. Diffuse cystic renal dysplasia and hepatic fibrosis is inherited in an Autosomal Recessive manner in dogs meaning that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup that is born to this pairing has a 25% chance of inheriting the disease and a 50% chance of inheriting one copy and being a carrier of the INPP5E gene mutation. Reliable genetic testing is important for determining breeding practices. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Norwich terriers that are not carriers of the mutation have no increased risk of having affected pups.
There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.
References
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Dillard KJ, Hytonen MK, Fischer D, Tanhuanpaa K, Lehti MS, Vainio-Siukola K, Sironen A, Anttila M. A splice site variant in INPP5E causes diffuse cystic renal dysplasia and hepatic fibrosis in dogs. PLoS One. 2018 Sep 20;13(9):e0204073. doi: 10.1371/journal.pone.0204073.
[PubMed: 30235266]
