Test Detail

Multi-disease and coat-colour panel targeted at the Rhodesian Ridgeback that groups six tests: degenerative myelopathy (DM exon 2, SOD1), haemophilia B (factor IX deficiency, F9), early-onset adult deafness (EOAD, EPS8L2), juvenile myoclonic epilepsy with photosensitivity (JME, DIRAS1), B-locus (brown/chocolate pigment, TYRP1) and D-locus d1 (dilution, MLPH). Haemophilia B is a severe X-linked coagulopathy; the two colour tests are morphological markers.

Applicable breed: Rhodesian Ridgeback. DM: the Rhodesian Ridgeback was one of the five breeds in the original study of the classic SOD1 variant (Awano 2009). Haemophilia B: F9 p.(G244E) variant described in the breed; no published carrier frequencies (limited data). EOAD: carrier frequencies not well quantified (limited data). JME: limited data on carrier and case frequency. B-locus and D-locus: multi-breed morphological markers; no breed-specific frequencies are published.

- Genotype breeding stock before mating; the panel covers six conditions/markers in a single sample\n- For the autosomal recessive conditions (DM, EOAD, JME): do not mate carrier × carrier — 25% risk of homozygotes per litter; a carrier may be mated with a clear animal and the offspring intended for breeding tested\n- For haemophilia B (X-linked): a carrier female transmits the mutated allele to 50% of the sons (affected males) and 50% of the daughters (carriers); do not mate carrier females and do not use affected males as breeding stock\n- For B-locus and D-locus: information to predict coat colours; it carries no disease risk\n- After a confirmed clinical case, do not repeat the parental mating and communicate the status to the buyer

DM is a diagnosis of exclusion: rule out spinal cord compression, disc herniation and neoplasia before attributing the presentation to SOD1. Haemophilia B is confirmed by a prolonged aPTT with normal PT, factor IX activity assay and genetic testing; in non-genotyped males, assess haemostatic coverage before surgery. EOAD is postnatal and progressive, so assessment in the puppy may be normal; it is confirmed by bilateral brainstem auditory evoked responses (BAER) and genetic testing, and must be differentiated from otitis and acquired deafness. JME requires clinical diagnosis (EEG, video monitoring) and exclusion of other epilepsies. The colour tests are informative, not diagnostic of disease.

1. Awano T et al. (2009). Genome-wide association analysis reveals a SOD1 mutation in canine degenerative myelopathy that resembles amyotrophic lateral sclerosis. Proc Natl Acad Sci U S A 106(8):2794-2799. PMID: 19188595
2. Mischke R et al. (2011). G244E in the canine factor IX gene leads to severe haemophilia B in Rhodesian Ridgebacks. Vet J. PMID: 20303304
3. Kawakami T et al. (2022). Early onset adult deafness in the Rhodesian Ridgeback dog is associated with an in-frame deletion in the EPS8L2 gene. PLoS One. PMID: 35385474
4. Wielaender F et al. (2017). Generalized myoclonic epilepsy with photosensitivity in juvenile dogs caused by a defective DIRAS family GTPase 1. Proc Natl Acad Sci U S A. PMID: 28223533
5. Wielaender F et al. (2018). Absence seizures as a feature of juvenile myoclonic epilepsy in Rhodesian Ridgeback dogs. J Vet Intern Med. PMID: 29194766
6. Candille SI et al. (2007). A beta-defensin mutation causes black coat color in domestic dogs. Science. PMID: 17947548
7. Schmutz SM et al. (2002). TYRP1 and MC1R genotypes and their effects on coat color in dogs. Mamm Genome. PMID: 12140685
8. Drögemüller C et al. (2007). A noncoding melanophilin gene (MLPH) SNP at the splice donor of exon 1 represents a candidate causal mutation for coat color dilution in dogs. J Hered. PMID: 17519392
9. OMIA:000263-9615 (Degenerative myelopathy); OMIA:000438-9615 (Haemophilia B); OMIA:002550-9615 (Deafness, EPS8L2-related); OMIA:002095-9615 (Epilepsy, generalized myoclonic, with photosensitivity); OMIA:001249-9615 (Coat colour, brown, TYRP1-related); OMIA:000031-9615 (Coat colour, dilution, MLPH-related).