Spinal Muscular Atrophy is a genetically inherited condition that weakens the voluntary muscles of infants and children and damages the nerve cells in the brain and spinal cord. This condition can result in having trouble performing day-to-day activities like walking, sitting upright, controlling the head, and even breathing. This condition is passed on genetically, and there are no cures available for this disorder. Read on to know about the symptoms and causes of spinal muscle atrophy.

• Cause

This condition results in changes in the composition of the survival motor neuron 1 (SMN1) and survival motor neuron 2 (SMN2). These genes are responsible for the production of proteins necessary for the proper functioning of motor neurons. These neurons transport the signal of action from the brain to the rest of the body. Aberrations in SMN 1 cause spinal muscular atrophy, while aberrations in SMN2 are responsible for controlling the severity of the condition.

Spinal muscular atrophy is a condition that is usually observed in babies and children. It is caused due to inheritance of a broken or mutated gene, found in chromosome 5, from both parents. Furthermore, there are different forms of SMAs that are not connected to aberrations in chromosome 5 and the deficiency of survival motor neurons.

• Signs and Symptoms

There are five types of SMAs named through type 0 to type 4 in the descending order of severity. The severity of each condition depends on the amount of SMN protein present in the motor neurons. The signs and symptoms amplify in their effect, as observed in each of the types of SMAs.

The following early signs can be observed in children suffering from SMA:

• In Type 0 SMA, the symptoms can be felt by the mother in her pregnancy before the child is even born. These include reduced movement felt in the womb; furthermore, newborn babies show severe weakness, heart defects, and facial paralysis.
• Slightly milder than type 0 SMA, newborn babies with type 1 SMA are usually weak and have difficulty supporting their heads or sitting. Their muscles are weaker, making it difficult to breathe or swallow food.

• Type 2 SMA is observed in babies between the ages of 3 to 15 months, exhibiting weakness in the muscles of the legs. These symptoms can be moderate or severe.
• In Type 3 SMA, symptoms are observed later in life (between 2-17 years of age) and are milder than other SMAs. They can walk and stand without much effort, but have difficulty in running or climbing flights of stairs. Symptoms like foot deformities, scoliosis, and respiratory muscle weakness are observed in adulthood.
• Type 4 SMA is observed in adulthood with very mild symptoms of weakness in the muscles of the thighs and upper arms. The patient is usually able to lead an ordinary life, and most of the symptoms can be managed with the help of exercises and physical therapy.