Genetic panel for the Cane Corso (Italian) grouping five autosomal recessive hereditary conditions described or validated in the breed: canine multifocal retinopathy 1 (CMR1, multifocal retinal lesions caused by BEST1), degenerative myelopathy (DM, SOD1 exon 2 variant), dental-skeletal-retinal anomaly (DSRA, multisystemic syndrome caused by MIA3), hyperuricosuria/hyperuricemia (HUU, renal defect of SLC2A9 with risk of urate uroliths) and neuronal ceroid lipofuscinosis 1 (NCL1, lysosomal neurodegenerative disease caused by PPT1). It affects the ocular, neurological, skeletal-dental and renal/urinary systems. Adjunctive test, not a substitute for clinical examination.

Applicable breed: Cane Corso (Italian). CMR1 and DSRA are characterized in the breed (DSRA with a private variant); DM and HUU are variants present in multiple breeds and NCL1 has been described in isolated Cane Corso cases. No population carrier frequencies have been published for the breed (limited data).

- CMR1: multifocal subretinal plaques with tapetal hyperreflectivity; vision usually preserved, a typical finding on fundus examination
- DM: ataxia and progressive paresis of the pelvic limbs in the adult, with muscle atrophy; non-painful at onset
- DSRA: dental hypoplasia, absence or fragility, skeletal abnormalities and retinal dysplasia or degeneration
- HUU: urate uroliths (radiolucent), dysuria, hematuria and urethral obstruction, especially in males
- NCL1: onset around 9 months of age with ataxia, weakness, disorientation, rhythmic head movements, kyphosis and visual and cognitive decline
- Progression is variable depending on the condition; NCL1 is progressive with no curative treatment

The causal variant of CMR1 was identified in the BEST1 gene (Guziewicz et al., 2007) and the Cane Corso is among the affected breeds (OMIA:001444-9615). Canine DM was associated with the SOD1 exon 2 variant (Awano et al., 2009), present in many breeds. DSRA in the Cane Corso was genetically characterized by Christen et al. (2021) as a private MIA3 splicing variant, with complete genotype-phenotype association in the family studied. HUU was attributed to the SLC2A9 variant described by Bannasch et al. (2008). NCL1 in the Cane Corso was described by Kolicheski et al. (2017) as a PPT1 splicing variant in an affected dog.

- Genotype Cane Corso breeding stock for BEST1, SOD1 exon 2, MIA3, SLC2A9 and PPT1 before mating
- Do not breed two carriers of the same variant (25 % homozygotes per litter)
- A carrier may be bred to a clear individual; test the offspring intended for breeding
- Exclude affected and homozygous animals from breeding
- After a confirmed case, do not repeat the parental mating and communicate the status to the buyer
- Remember that DM has incomplete penetrance: the genotype alone does not determine onset or severity
- Complement with ophthalmological, dental and orthopedic examination of the breeding stock

CMR1 must be differentiated from other hereditary retinopathies and confirmed by fundus examination; the test is specific for the cmr1 variant and does not cover cmr2 or cmr3. DM requires ruling out compressive causes of myelopathy (MRI or myelography) before attributing it to SOD1. DSRA requires combined dental, skeletal and ophthalmological assessment. HUU is confirmed by stone analysis (urate uroliths) and urine culture, and its management is dietary with urinary monitoring. NCL1 is a progressive neurodegenerative disease with no curative treatment, with a differential diagnosis against other degenerative ataxias.

1. Guziewicz KE et al. (2007). Bestrophin gene mutations cause canine multifocal retinopathy. Invest Ophthalmol Vis Sci 48:1959-1967. PMID: 17460247
2. Awano T et al. (2009). Genome-wide association analysis reveals a SOD1 mutation in canine degenerative myelopathy. Proc Natl Acad Sci USA. PMID: 19188595
3. Christen M et al. (2021). MIA3 Splice Defect in Cane Corso Dogs with Dental-Skeletal-Retinal Anomaly (DSRA). Genes (Basel) 12:1497. PMID: 34680893
4. Brown AT et al. (2024). Dental Abnormalities in Two Dental-Skeletal-Retinal Anomaly-Positive Cane Corso Dogs: A Case Series. J Vet Dent. PMID: 38146186
5. Bannasch D et al. (2008). Mutations in the SLC2A9 gene cause hyperuricosuria and hyperuricemia in the dog. PLoS Genet. PMID: 18989453
6. Kolicheski A et al. (2017). Homozygous PPT1 splice donor mutation in a Cane Corso dog with neuronal ceroid lipofuscinosis. J Vet Intern Med 31:149-157. PMID: 28008682
7. OMIA:001444-9615 (CMR1), OMIA:000263-9615 (DM), OMIA:002465-9615 (DSRA), OMIA:000584-9615 (HUU), OMIA:001504-9615 (NCL1).