Other names: Degenerative Myelopathy Early-Onset Risk Modifier- Pembrooke Welsh Corgi
Affected gene: SP110
Transmission: Dominant Modification
Mutations: SP110 intron11 canfam3.1 25 g.42439453 C/T (on canfam2 25 45,437,568)
SP110 exon9 canfam3.1 25 g.42445205 A/G (on canfam2 25 45,443,320)
OMIA link: 000263-9615

Appropriate breeds for testing:  Pembroke Welsh Corgi

Symptoms:
Genetic testing of the SP110 gene in Pembroke Welsh Corgi is referred to as ¨modifier¨. It is associated with an increased risk for ¨conventional¨ degenerative myelopathy (CanFam3.1 mutation chr.31 g.26540342G>A c.118G>A) and increases the risk of autosomal dominant degenerative myelopathy. That is, dogs that have two copies of the SOD1 gene mutation need only 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 only necessary for dogs that are at risk (affected) for degenerative myelopathy.
According to the article by Ivansson et al. 2016, a frequency haplotype was determined in the population (see image) and it was determined that the ATGGT haplotype is different 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 in 4% of unaffected dogs. The canfam3.1 25:42439453 locus (on canfam2 25 45,437,568 intron 11) discriminates this haplotype (ATGGT) from the other 3 (GCAAA, GCGGT, ACAAA, see additional image).
In addition, 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).
*** Betagene 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 risk of canine degenerative myelopathy. USA PNAS 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]