Breeds Affected: Maine Coon
Samples Accepted: Blood, Buccal Swabs
Disease Information: Spinal Muscular Atrophy (SMA) is caused by the loss of nerves going from the spinal cord to the leg muscles, which in turn causes those muscles to atrophy. Symptoms may be noted by 12-16 weeks of age and include weakness, gait abnormalities that get worse with time, and tremors. Many affected cats are able to survive to adulthood.
Inheritance Information: SMA 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 cat is normal, and cannot produce affected offspring.
N/sma The cat is a carrier, and can pass the allele on to approximately 50% of any offspring. If bred to another N/sma carrier, approximately 25% of the offspring will be normal, 50% will be carriers, and 25% will be affected.
sma/sma The cat is affected. If bred to a normal animal, 100% of the offspring will be carriers. If bred to an N/sma carrier, 50% of the offspring will be carriers and 50% will be affected.
– Carriers may be bred to normal animals (N/sma 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/sma x N/sma) is not recommended due to the possibility of 25% of the offspring being affected.
– Affected animals (sma/sma) should not be used for breeding.
Test Information: This mutation test identifies a 140 kb deletion that encompasses parts of the LNPEP and LIX1 genes.
Fyfe, J.C., Menotti-Raymond, M., David, V.A., Brichta, L., Schäffer, A.A., Agarwala, R., Murphy, W.J., Wedemeyer, W.J., Gregory, B.L., Buzzell, B.G., Drummond, M.C., Wirth, B., O’Brien, S.J.: An approximately 140-kb deletion associated with feline spinal muscular atrophy implies an essential LIX1 function for motor neuron survival. Genome Res 16:1084-90, 2006. Pubmed reference: 16899656. Doi: 10.1101/gr.5268806.
Further information is available at the Online Mendelian Inheritance in Animals website.