Spinal Muscle Atrophy, or SMA, is a rare genetic disorder that progressively impacts the nervous system as well as the muscles. This condition is known to occur to 1 in every 6,000 to 10,000 people. SMA causes the gradual death of the muscle cells and affects the lower motor neurons from the spinal cord to the muscle cells, which are primarily responsible for all movements (i.e., walking, crawling, reaching, grasping, swallowing, and even breathing).
In general, SMA is categorized into four main types: type 1, 2, 3, and 4. The categorization into types is based on the age that the onset happens and the physical milestones that are the highest. Each individual with SMA has different experiences of the condition even if categorized under the same type, and the progression rates differ from individual to individual, and consequently, the treatment and care decisions are made. SMA types include the following:
- SMA type 1
This is one the most severe and most commonly diagnosed in an infant within 6-months of birth. Babies that are born with this type of SMA face quite a lot of physical challenges such as muscle weakness, and trouble with coughing, breathing and swallowing. The babies in this type of scenario have breathing assistance and feeding tube assistance given. This type of SMA is fatal and occurs in more than 60% of the cases.
- SMA type 2
This type of SMA is usually diagnosed between six months to two years of age. The first signs of symptoms are usually identifiable with the delay in motor milestones or complete failure to meet the required milestones. Those affected with SMA type 2 would be able to sit up without much help but would need some form of assistance. However, they will be unable to walk and may require a wheelchair.
- SMA type 3
This type of SMA is generally diagnosed after 18 months to before 3 years of age. There are chances that SMA would not be diagnosed until the late teen years. Those affected by SMA type 3 would have the ability to walk for some time but their mobility will soon be limited and they will eventually have to end up with a wheelchair for movement.
- type 4
This type of SMA is quite rare and usually often surfaces only during adulthood. This condition causes the impairment of mild motor abilities, and even if the symptoms can start around the age of 18, the actual onset is severe after the age of 35 in a majority of the cases.
- Other forms of SMA
There are also other forms of SMA that can occur as a result of the mutation in the genes rather than the specific SMN 1 gene. Some of these variations in the condition include Spinal Muscular Atrophy Respiratory Distress (SMARD), Distal SMA, and Kennedy’s Disease.
