Xanthinuria type 2 / xanthine urolithiasis (MOCOS c.232G>T) - Manchester Terrier

What does this test examine?

This genetic test examines the MOCOS variant c.232G>T in dogs. The variant causes Xanthinuria type 2 / xanthine urolithiasis, also described as hereditary xanthinuria, xanthine stones, xanthine uroliths, xanthine nephrolithiasis or an inherited disorder of purine metabolism.

This analysis is intended for Manchester Terrier. In this disorder, xanthine accumulates in the urine. Because xanthine has low solubility, crystals and urinary stones can form in the bladder, urinary tract or kidneys.

What does xanthinuria mean?

In normal purine metabolism, xanthine is further broken down into more soluble end products. With this variant, molybdenum cofactor sulfurase does not function sufficiently, causing higher amounts of xanthine to be excreted in urine. Not every dog shows signs immediately, but genetically affected dogs have a clearly increased risk of xanthine crystals, bladder stones, kidney stones and secondary kidney damage.

Signs can include frequent or difficult urination, straining, blood in the urine, pain, recurrent urinary problems and, in severe cases, life-threatening urinary obstruction. The first problems can appear from a young age, but may also become visible later. Diet, water intake, sex and urine properties can influence how quickly stones develop.

Inheritance and result

This trait is inherited as autosomal recessive. A dog with two normal copies is clear for the tested variant. A dog with one copy is a carrier: usually healthy, but important for breeding. A dog with two copies is genetically affected; this genotype causes the tested form of xanthinuria.

The result labels are GG, GT and TT.

Practical value of this test

This test is valuable because xanthinuria may only become obvious once urinary signs or stones are already present. DNA testing helps breeders, owners and veterinarians recognise inherited risk earlier and make better decisions for breeding, follow-up and management.

For breeders and owners

• Distinguishes clear, carrier and genetically affected dogs.
• Helps avoid carrier-to-carrier matings and prevent affected puppies.
• Provides useful information for purchase, sale and selection of breeding animals in risk lines.
• Supports targeted screening of relatives when a carrier or affected dog is found.
• Helps plan early attention to water intake, diet and urinary monitoring in genetically affected animals.