About Spinal Muscular Atrophy (SMA):
- SMA is a group of inherited neuromuscular disorders cause certain muscles to become weak and waste away.
- It is a progressive disorder that can cause life-threatening
What Happens in SMA?
- In SMA, the nerves that control muscle strength and movement break down.
- These nerves (called motor neurons) are in the spinal cord and lower part of the brain.
- They can't send signals from the brain to the muscles to make them move.
- Because the muscles don't move, they get smaller (or atrophy).
- The weakness in SMA tends to be more severe in the muscles that are close to the center of the body (proximal muscles) than in the muscles farther away from the body’s center (distal muscles).
- Muscle weakness tends to worsen with time.
What Causes SMA?
- Motor neurons need a protein called SMN (survival motor neuron) to work.
- Most kinds of SMA are caused by a problem with a gene that makes this protein, called the SMN1 gene.
- When this gene mutates (changes in some way), it can’t make enough protein for the motor neurons to work properly.
- The motor neurons break down and can't send signals to the muscles.
- Types of SMA:
- It is classified as type 1, 2, 3, or 4 depending on age of onset.
- SMA type 1 (infantile-onset SMA or Werdnig-Hoffman disease): It is the most severe It is also the most common. Babies with this type usually show signs of the disease before 6 months of age.
- SMA type 2 (intermediate SMA): It is a moderate to severe type of SMA. It is usually first noticed between 6 and 18 months of age.
- SMA type 3 (juvenile SMA, Kugelberg Welander syndrome): It is the mildest type that affects children. The signs of the disease usually show up after age 18 months.
- SMA type 4 (adult SMA): It is rare and often mild. It usually causes symptoms after 21 years of age.
- The term "5q SMA" is often used to refer to all 4 common types of SMA.
- Healthcare providers classify them based on the age of onset, as well as the severity and life expectancy.
- Treatment:
- There isn’t a cure for SMA.
- Treatment for SMA mainly seeks to manage symptoms and prevent complications.
