Multidisease genetic panel for the Curly Coated Retriever that brings together four molecular tests: cord1-PRA progressive retinal atrophy, exercise-induced collapse (EIC), glycogen storage disease type IIIa (GSDIIIa) and degenerative myelopathy (DM exon 2). Each condition has its own molecular basis and inheritance. The panel is complementary to ophthalmic, neurological and metabolic examination in breeding selection. The cord1 test is offered as a risk marker, without published breed-specific validation in the breed.

Applicable breed: Curly Coated Retriever. EIC and GSDIIIa are documented in the breed; the DM SOD1 variant is pan-breed and the RPGRIP1 (cord1) variant is a marker present in multiple breeds, but without breed-specific validation published in the Curly Coated Retriever. Reliable carrier frequencies in the breeding population are not published systematically (limited data).

- Reduced night vision and progressive retinal atrophy (cord1-PRA)\n- Progressive blindness with abnormal fundus\n- Weakness after intense exercise with staggering gait and collapse (EIC)\n- Rapid recovery when exercise stops (EIC)\n- Lethargy, failure to thrive, hepatomegaly and myopathy from a young age (GSDIIIa)\n- Progressive hindlimb paresis with proprioceptive ataxia (DM)

Canine cord1-PRA was associated with a 44 bp insertion in exon 2 of RPGRIP1 described in the Miniature Long-haired Dachshund and the English Springer Spaniel (Mellersh et al., 2006); there is no breed-specific validation in the Curly Coated Retriever. Exercise-induced collapse was associated with the DNM1 c.767G>T p.(Arg256Leu) variant in the Labrador Retriever (Patterson et al., 2008) and has also been documented in the Curly Coated Retriever. Canine GSDIIIa was characterised in the Curly Coated Retriever as a defect of the glycogen debranching enzyme (amylo-1,6-glucosidase) caused by a deletion in the AGL gene (Gregory et al., 2007; Yi et al., 2012), NOT GBE1. Canine DM was linked to the SOD1 exon 2 variant (Awano et al., 2009).

- Genotype breeding animals before mating; the panel covers four conditions in a single sample\n- For EIC, GSDIIIa and DM (recessive): do not mate two carriers — 25 % risk of affected homozygotes; carrier × clear is safe if the offspring intended for breeding is tested\n- For cord1-PRA: interpret the combined RPGRIP1 + MAP9 genotype, not the isolated variant, and with caution due to the lack of breed-specific validation\n- For DM: mutated homozygotes are not a breeding priority; mate carriers with clear animals\n- After a confirmed clinical case, do not repeat the parental mating and communicate the status to the buyer

cord1-PRA requires interpretation of the combined RPGRIP1/MAP9 genotype — the RPGRIP1 variant alone may be asymptomatic and its validation in the breed is limited. Complementary annual ophthalmic examination (ECVO/CERF). EIC must be differentiated from collapse due to arrhythmogenic cardiomyopathy, laryngeal myopathy and adynamic crises. GSDIIIa is confirmed by enzymology (debranching enzyme deficiency) and molecular study; the differential diagnosis includes other glycogenoses and congenital myopathies. DM is a diagnosis of exclusion: rule out spinal cord compression before attributing the picture to SOD1.

1. Mellersh CS, et al. Canine RPGRIP1 mutation establishes cone-rod dystrophy in miniature longhaired dachshunds as a homologue of human Leber congenital amaurosis. Genomics. 2006. PMID: 16806805.
2. Patterson EE, et al. A canine DNM1 mutation is highly associated with the syndrome of exercise-induced collapse. Nat Genet. 2008. PMID: 18806795.
3. Gregory BL, et al. Glycogen storage disease type IIIa in curly-coated retrievers. J Vet Intern Med. 2007. PMID: 17338148.
4. Yi H, et al. Characterization of a canine model of glycogen storage disease type IIIa. Dis Model Mech. 2012. PMID: 22736456.
5. Awano T, et al. PNAS. 2009. PMID: 19188595.
OMIA:001432-9615 (cord1/RPGRIP1); OMIA:001466-9615 (EIC); OMIA:001577-9615 (GSDIIIa); OMIA:000263-9615 (DM).