SMA - Spinal Muscular Atrophy
SMA Spinal Muscular Atrophy symptoms
Spinal Muscular Atrophy (SMA) is a hereditary genetic disease of Maine Coon caused by the degeneration of neurons responsible for voluntary and conscious movements (walking, running, holding the head, swallowing, etc.).
Symptoms of SMA may be more or less severe and occur primarily in a young kitten, although cases have been reported in adult cats.
In the first months of life, there is a muscle weakness that becomes really obvious at the age of 3 or 4 months.
Affected kittens have difficulties in walking; their gait is strange with a sway of the hindquarters and sometimes slight tremors.
At the age of 5 to 7 months, they become clumsy and lose agility in jumps.
It can also be observed in some cases breathing difficulties.
After this phase of rapid evolution, the SMA stabilizes generally to evolve more slowly from 10 months. There may be remission phases in adult life.
Some cats with SMA live with more or less severe symptoms up to 9 years.
SMA affected cats feel no pain, they eat normally and play greedily. Muscular atrophy affecting only the hind limbs, some seriously affected cats move by crawling with the front legs.
This disease is similar to SMA type III in humans where the individual can walk but falls frequently.
The SMA detection DNA test can be performed from 6 to 8 weeks. Like all genetic tests, this test is very reliable.
The test is performed from a buccal swab, fast and easy to perform.Here is the list of the different types of samples that are accepted for this test :
- Buccal swab
- Blood in EDTA tube
- Blood in dry tube
Screening and interpretation of results
Maine Coon SMA is caused by 140 kb suppression on the LIX1 gene.
The expression of the LIX1 gene is largely restricted to the central nervous system, mainly in motoneuron neurons, thus explaining the loss of agility and balance of affected cats.
This mutation is hereditary according to an autosomal recessive mode with complete penetrance.
The test does not determine the severity of the SMA.
Motor neurons of the spinal cord affected by the SMA (in red).
Available breed for the test : SMA – Spinal Muscular Atrophy
The following breed is recognized :
- Maine Coon
Understanding results of the test : SMA – Spinal Muscular Atrophy
Gene Mutation : LIX1 140kb del, exons 4-6
Heredity : autosomal recessive (more information)
Penetrance : complete (more information)
|Test result||SMA – Spinal Muscular Atrophy status (LIX1 140kb del, exons 4-6)||Health status|
|N/N||No copy of the SMA mutation||Animal is normal (clear)|
|N/SMA||1 copy of the SMA mutation||Animal is normal (clear)|
|SMA/SMA||2 copies of the SMA mutation||Animal is, will or could be affected|
Cross table of the test : SMA – Spinal Muscular Atrophy
|Mother N/N||Mother N/SMA||Mother SMA/SMA|
|Father N/N||100% N/N||50% N/N|
|Father N/SMA||50% N/N|
|Father SMA/SMA||100% N/SMA||50% N/SMA|
Certificate example for the test : SMA – Spinal Muscular Atrophy
Click on the example certificate below to open it.
John C. Fyfe et al.: An ~140-kb deletion associated with feline spinal muscular atrophy
implies an essential LIX1 function for motor neuron survival , Genome Res. 2006 16: 1084-1090.