Test Detail

Genetic test for type I-A cystinuria (autosomal recessive) in dogs: it detects the nonsense variant SLC3A1 c.586C>T (p.Arg196*) described in the Newfoundland and Landseer. Cystinuria is a defect in tubular reabsorption of cystine that produces crystalluria and stones, with a risk of urinary obstruction. The molecular test is complementary to —not a substitute for— urinalysis and stone analysis.

Applicable breeds: Newfoundland and Landseer (OMIA:000256). Cystinuria in general has been described in more than 60 breeds with different variants; population data on carriers for this specific form are limited.

- Do not mate two carriers: 25 % risk of affected homozygotes
- Carrier x clear: offspring intended for breeding must be tested; plan a progressive replacement with clear animals
- In homozygotes: generous hydration, alkaline urine and monitoring of crystalluria; watch for obstruction especially in males
- After a confirmed clinical case, do not repeat the parental mating and communicate the status to the buyer
- Confirm with the laboratory that the test variant corresponds to the animal's breed

Differential diagnosis with other forms of cystinuria (SLC7A9, androgen-dependent forms of other breeds) and with oxalate or urate uroliths. Diagnosis by hexagonal crystals in sediment or stone analysis; metabolic screening (nitroprusside, urinary amino acids) can detect the disease before the clinical picture. The c.586C>T variant is different from that of the Labrador (c.350del) and of the Bulldog (haplotype c.[574A>G;2092A>G]), so a negative result for this test does not rule out cystinuria due to another variant.

1. Henthorn PS et al. 2000, polimorfismo del gen SLC3A1 y mutación sin sentido en Terranova con cistinuria (PMID 11129328)
2. Brons AK et al. 2013, SLC3A1/SLC7A9 y nueva clasificación de la cistinuria canina (PMID 24001348)
3. Revisión de la cistinuria en perro y gato 2021 (PMID 34438894)
4. OMIA:000256 Cistinuria, type I-A