Cystinuria English Bulldog and French Bulldog Type (CYS)

Acronym:	CYS
Gene:	SLC3A1; SLC7A9
Mutation:	c.574A>G, c.2092A>G; c.649G>A
Inheritance:	Autosomal Recessive in SL3CA1, Incompletely Recessive in SLC7A9
Sample type:	CHS (Cheek Swab), WBE (Whole Blood EDTA)

Genetics and characteristics

Cystinuria English Bulldog and French Bulldog type is an inherited disorder affecting the urinary tract of a dog. It is characterized by the formation and accumulation of cystine stones in the kidney, bladder, or ureter. So far, cystinuria has been recognized in humans, dogs, cats, and wolves. Canine cystinuria affects over 60 dog breeds, while the genetic testing for this disorder is available for Labrador Retriever, Newfoundlander, Landseer, Miniature Pinscher, Australian Cattle dog breed, and English and French bulldog. Generally, canine cystinuria can be divided into three groups, type I (autosomal recessive), type II (autosomal dominant), and type III (also known as non-type I). Unlike type I and II, type III cystinuria shows a complex inheritance pattern and is usually found in male dogs.

In properly functioning kidneys, blood is filtered in order to create urine, and cystine is reabsorbed back into the bloodstream within the tubules. Dog affected with cystinuria cannot reabsorb cystine, which causes cystine accumulation and crystallization in the urine. Some crystals may bind with calcium molecules, grow and accumulate in the kidneys or in the bladder, creating blockages in the urinary tract. These stones may also be a source of bacterial infection. These conditions can lead to stranguria, hematuria, urinary obstruction, and renal failure. Cystinuria can be without any effect on the life-length of the dog, unless in cases of complications, such as obstruction, recurrent infections, or surgical complications. The development of cystinuria Bulldog type is also influenced by hormones, particularly testosterone. Due to this reason, affected bulldogs affected should be neutered in order to prevent the development of cystinuria symptoms. Certain medications may also be used in order to dissolve cystine stones.

Three mutations in SLC3A1 and SLC7A9 genes have been associated with the development of cystinuria in English and French bulldogs. A dog is considered a carrier when is heterozygous for one or more out of three mutations. The SLC3A1 mutation shows an autosomal recessive mode of inheritance. That means that cystinuria will develop in dogs that inherited two mutated alleles from both parents (recessive homozygous). Heterozygous dog inherited the mutated allele only from one of their parents and does not show any signs and is considered clinically healthy, but can pass the mutated allele to their offspring. The SLC7A9 mutation shows incomplete recessive inheritance i.e. even heterozygous dogs may develop symptoms of cystinuria.

 

Results Reported As

Test Result	Interpretation of test result

 

 

 

 

 

 

 

 

 

 

References:

Ruggerone B., Marelli SP., Scarpa P., Polli M. (2016): Genetic evaluation of English bulldogs with cystine uroliths. Veterinary Record. doi: 10.1136/vr.103615