Spinal muscular atrophy, or SMA, is a rare autosomal recessive disease affecting 1 in 10,000 people globally. The condition, commonly referred to as SMA is usually characterized by progressive muscle degeneration hence the name atrophy and weakness as well.

According to studies, SMA occurs when there is a deficiency of the protein known as SMN. The protein is responsible for the proper functioning and survival of the motor neurons so when there is a deficiency, they end up breaking down and fail to perform their function which is to relay signals between the brain and the muscles. As a result, the muscles end up wasting away (atrophy) and also become weaker. Even though SMA symptoms vary depending on the level of protein deficiency, one suffers, here are the common symptoms among all types:

• Difficulties in sleeping and weight gain
• Frequent pneumonia
• Scoliosis
• Stiff joints
• Breathing problems
• Difficulties in eating and swallowing
• Limited mobility
• Spontaneous tongue movements
• Delayed gross motor skills

There are five spinal muscle atrophy main types as shown below:

1. SMA type 0
This is the most severe SMA form. It often affects newborns, and its symptoms begin kicking in during the late stage of pregnancy as the fetus becomes less active than usual. Once born, the infant often suffers from severe muscle weakness and hypotonia. As a result, they often have little ability to move and problems with breathing and swallowing. They also suffer from respiratory problems, and most infant with this type of SMA often die within the first six months after birth.

2. SMA type 1a
Also known as the Werdnig-Hoffman disease is to some extent similar to SMA type 0. However, it is more severe and more common than the latter. Unlike type 0, the newborn often appears normal but soon begins exhibiting the signs of SMA. This happens within the first six months, and unfortunately, they may not survive. Type 1 SMA symptoms include extreme hypotonia, lack of head control, limb weakness, difficulties in breathing and swallowing due to tongue fasciculation and a weak cry among many others.

3. SMA Type II
Also known as the Dubowitz disease, symptoms of SMA type II often become apparent between 6 and 12 months. This means that all through, the infant seems quite normal. Between six and nine months, an SMA type II infant is usually able to sit independently; however, they cannot walk without assistance. Their muscle atrophy is often more pronounced in their arms. Other signs of type II SMA include respiratory problems, chewing problems, areflexia and hypotonia among many others.

4. SMA Type III
This type of SMA accounts for 30% of SMA patients and usually begins displaying its signs at the age of 18 months and early adulthood. Even though the patient can stand and walk without assistance, they often fall repeatedly and experience trouble climbing and going down the stairs. Even though they can walk and stand on their own, they may lose these abilities later in life due to weak muscles. However, they may live as long as unaffected people.

5. SMA Type IV
This is the adult form of SMA as it often manifests itself at the age of 20 or 30 and even in some cases much later than that. It is often quite mild, and the patient usually retains their ability to walk and move independently but might experience moderate muscle twitching and tremors.