Degenerative Myelopathy (DM) is a progressive disease of the spinal cord in older dogs. In many breeds, the disease is strongly correlated with a mutation in the superoxide dismutase 1 (SOD1) gene often referred to as the 118G>A mutation. This mutation is tested for using the standard DM test (see above). More recently, a second mutation in the SOD1 gene has been detected in the Bernese Mountain Dog (BMD) and is referred to as the SOD1B 52A>T mutation. To date, a single BMD with two copies of the 52A>T mutation and no copies of the 118G>A mutation has been clinically diagnosed with DM. In one additional study, a single BMD that tested ‘CARRIER’ for both the 118G>A and the 52A>T showed clinical signs of DM highlighting the potential for complex mutation interactions.
The SOD1B mutation is detected much less frequently (3%) than the 118G>A mutation (38%) in BMD but could play a role in disease progression. In an effort to further understand the disease in the breed, the SOD1B test is being offered. Please share the results in an open database such as The Berner-Garde Foundation (http://www.bernergarde.org/home/), a group established to collect, maintain and disseminate information about genetic diseases observed in the BMD. Through tracking of the health and SOD1B status, a better understanding of the impact of this mutation on the breed can be determined.
Bernese Mountain Dog
A (CLEAR/NORMAL): These dogs have two normal copies of DNA. To date, no dogs tested as ‘CLEAR/NORMAL’ have been confirmed to have DM.
B (CARRIER/NOT AFFECTED): These dogs have one copy of the 52A>T mutation and one normal copy of DNA. One compound carrier (118G>A carrier, 52A>T) to date has been confirmed to have DM.
C (AT RISK/AFFECTED): These dogs have two copies of the 52A>T mutation and may develop DM during their lifetime. At this point, the SOD1B mutation can be interpreted as being ‘AT RISK’ of developing DM within the animal’s lifetime. For dogs showing clinical signs with a presumptive diagnosis of DM, ‘AT RISK/AFFECTED’ test results can be used as an additional tool to aid in the diagnosis of DM.