Spinal Muscular Atrophy

Feline spinal muscular atrophy (SMA) is a fully penetrant, autosomal recessive lower motor neuron disease in domestic cats and Maine Coons, It causes the loss of spinal cord neurons (nerves) that control muscles in the limbs. This leads to muscle weakness and clinical signs become apparent by 3-4 months of age, signs can be seen at younger ages depending on the severity. The condition is nether fatal or painful and affected cats can life a normal life indoors. Affected felines may be too weak to jump by 6 months of age.

The mutation is inherited as an autosomal recessive trait, meaning that two copies of the mutant gene are required for SMA to develop.

Testing can be done by, Optimal selection https://optimal-selection.com/products/optimal-selection-feline with the turn over time of a week. UCDAVIS https://vgl.ucdavis.edu/test/maine-coon-sma this turn over time can take up to 3+ weeks.

Squares = males, circles = females, open symbols = clinically normal cats, and filled symbols = affected cats. Numerals above certain symbols indicate the number of offspring of the indicated gender and phenotype obtained in multiple litters from the indicated mating. The female indicated by A is an ancestor common to every parent of an affected cat, and all cats in this family were purebred Maine coon cats.

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Alleles: N = Normal Unaffected, S = Spinal muscular atrophy

Cats with S/S genotype will have spinal muscular atrophy, a non-fatal but disabling condition.

  • N = Normal spinal muscular atrophy genetic test result means that the cat does not have the known genetic mutation causing spinal muscular atrophy in Maine Coon cats.

  • N/S = Carrier spinal muscular atrophy genetic test result means that the cat has one copy of the spinal muscular atrophy mutation. The cat will not have spinal muscular atrophy but may pass the mutation to their offspring.

  • S/S = Affected spinal muscular atrophy genetic test result means that the cat has two copies of the spinal muscular atrophy mutation. The cat will have spinal muscular atrophy, and pass the gene on to offsprings if allowed to breed.

A controlled study was done in Michigan using Maine coons and domestic cats. This study offered many doors into understanding SMA and it's relativity to SMA found in humans.

"Michigan State University (MSU) or at the Nantes Veterinary School (Centre de Boisbone, ONIRIS, Nantes, France). Animals at MSU were raised and euthanized according to protocols approved by the university's Institutional Animal Care and Use Committee (IACUC) and which adhered to National Institutes of Health guidelines. Experiments performed at the Nantes Veterinary School were approved by the regional ethics committee and were carried out according to European guidelines for the care and use of experimental animals. Cats were genotyped by multiplex PCR as previously described"

"Model for motoneuron degeneration and the underlying signaling network in SMA. Motoneuron loss observed in post mortem analyses is preceded by a functional degeneration of central synapses and the neuromuscular junction. The subsequent axonal damage induces a chromatolytic phenotype of the motoneurons. During disease progression those processes become less reversible indicated by a reduced regenerative capacity. This is reflected by a growing network of dysregulated signaling nodes with an increased fraction of SMN-irreversible (black) vs. SMN-reversible (blue) signaling mediators. SMN-restoration restores blue nodes only. The relative number of SMN-restorable nodes becomes reduced over time as illustrated in this hypothetical scheme. Highly connected SMN-irreversible (black) nodes may be potent treatment targets (arrow). Those nodes may be critical regulators for a module involved in a specific degenerative process."