Other Names: Degenerative Myelopathy Modifier Gene, Degenerative Myelopathy Early-Onset Risk Modifier - Pembroke Welsh Corgi
Affected Gene: SP110
Transmission: Dominant modification

Mutations:
SP110 Intron 11: CanFam3.1 25 g.42439453 C/T (on CanFam2 25 45,437,568)
SP110 Exon 9: CanFam3.1 25 g.42445205 A/G (on CanFam2 25 45,443,320)
OMIA Link: 000263-9615

Breeds Recommended for Testing: Pembroke Welsh Corgi

Symptoms:
The genetic test for the SP110 gene in Pembroke Welsh Corgis is a modifier associated with an increased risk for conventional degenerative myelopathy (mutation CanFam3.1 chr.31 g.26540342G>A c.118G>A). The mutation increases the risk of degenerative myelopathy in an autosomal dominant manner. This means that dogs with two copies of the SOD1 mutation only need to inherit one copy of the SP110 gene mutation to be at an increased risk of developing degenerative myelopathy. The degenerative myelopathy modifier test (Pembroke Welsh Corgi type) is necessary only for dogs that are at risk (affected) by degenerative myelopathy.
According to Ivansson et al., 2016, a frequency haplotype was determined in the population, and it was found that the ATGGT haplotype differs between affected and unaffected PWC. The ATGGT haplotype is associated with an increased risk, as it is present in 40% of affected dogs, but only 4% of unaffected dogs. The locus CanFam3.1 25: 42439453 (on CanFam2 25 45,437,568 intron 11) allows for discrimination of this haplotype (ATGGT) from the other three (GCAAA, GCGGT, ACAAA).
Furthermore, the study revealed that locus 25:42445205 (on CanFam2 25 45,443,320 exon 9) is the strongest associated SNP (P = 2, 7 × 10−8).
Bêtagène tests both loci (SP110 locus 11 and exon 9).
References:
  
Ivansson EL, Megquir K, Kozyrev SV, et al. (2016). Variants within the SP110 nuclear body protein modify the risk of canine degenerative myelopathy. PNAS USA E3091-E3100. PubMed: 27185954
  
Shelton GD, Johnson GC, O’Brien DP, et al. (2012). Degenerative myelopathy associated with a missense mutation in the superoxide dismutase 1 (SOD1) gene progresses to peripheral neuropathy in Pembroke Welsh Corgis and Boxers. J Neurol Sci. 318(1-2):55-64. PubMed: 22542607