Breeds Affected: American Bulldog
Samples Accepted: Blood, Buccal Swabs
Disease Information: Nemaline myopathy is a disease in which a mutation in an important structural protein causes abnormal muscle development. Affected pups may show symptoms as early as 8 weeks of age, with muscle atrophy and weakness, tremors, and exercise intolerance. Pups are generally humanely euthanized before one year of age due to poor quality of life.
Inheritance Information: Nemaline Myopathy is autosomal recessive, meaning that animals with two copies of this allele will be affected. Animals with one copy of the gene will be clinically-normal carriers.
The possible genotypes are:
N/N The dog is normal, and cannot produce NM-affected offspring.
N/nm The dog is a carrier of NM, and can pass the allele on to approximately 50% of any offspring. If bred to another N/nm carrier, approximately 25% of the offspring will be normal, 50% will be carriers, and 25% will be affected.
nm/nm The dog is affected with NM. If bred to a normal animal, 100% of the offspring will be carriers. If bred to a N/nm carrier, 50% of the offspring will be carriers and 50% will be affected.
– Carriers may be bred to normal animals (N/nm x N/N) without any risk of producing affected offspring. The offspring should be tested before breeding to determine if they are carriers or normal.
– Breeding two carriers (N/nm x N/nm) is not recommended due to the possibility of 25% of the offspring being affected.
– Affected animals (nm/nm) should not be used for breeding.
Test Information: This test identifies a single nucleotide change in the NEM gene. The mutation has not been found outside of one family of American Bulldogs. For this reason, the test is not currently on the list of routine tests recommended for the breed; however any American Bulldog with muscle disease, or its relatives, should be tested to rule out Nemaline Myopathy.
This mutation was discovered, and genetic test developed, by CAG and academic collaborators.