Breeding Recommendations for SMA

SMA is a very serious disorder, but fortunately it is also extremely rare.

After 15 years of registering results, we have found that SMA is not as widespread as once believed. Therefore, starting in 2025, we will only recommend testing cats from known affected lines. We will register test results exclusively from these lines, as well as any new carriers that might be found through panel tests. 

A 2022 study by Anderson and colleagues identified only 12 carriers among 2.121 screened Maine Coons (approximately 0,6%). In the nearly 15 years that PawPeds has collected DNA results, no new carriers have been observed outside of the known carrier lines. At the current carrier frequency, an affected kitten would be expected in roughly 125.000 Maine Coons, if they are bred randomly. 

Recommendations

Since a DNA test is available for identifying both carriers and affected cats for SMA, we recommend the following protocols for breeding programs:

Test Recommendations:

• Relatives in Risk: It is strongly recommended to test any cat that has a relative known to be a carrier or affected.
• New Foundation Lines: This is not because they are particularly risky, but testing for everything is recommended in order to know what is brought in. 
• Safe Lines: It is not necessary to test cats where the parents are clear from SMA (N/N) or when they are from known safe lines. 

See "How to test", for more information how to test and how to send in results.

Breeding recommendations:

• Using Carriers: Carriers may be used for breeding, but only when paired with cats that are normal for the SMA mutation. Remember that offspring has 50 % risk of being carriers.
• Informing Buyers: All buyers of carrier kittens or kittens with an unknown status from pairings where both parents are not negative must be informed about the disease and the risks associated with using the kitten for breeding—unless the kitten or cat is neutered. Although heterozygous carriers never show symptoms of the disorder, pet buyers should fully understand the nature of the disease, especially if they might later decide to breed the pet without contacting the breeder.
• Excluding Affected Cats: Affected cats (with both SMA genes defective) should not be used for breeding.