Spinal Muscular Atrophy is a genetic disease affecting the part of the nervous system that controls voluntary muscle movement.
Most of the nerve cells that control muscles are in the spinal cord, which accounts for the word Spinal in the name of the disease. Moreover, Spinal Muscular Atrophy is Muscular because its primary effect is on muscles, which do not receive signals from these nerve cells. Finally, Atrophy is the medical term for getting smaller, which is what generally happens to muscles when they are not active.
There are four types of SMA (Type 1-4) that differ in age of onset, symptoms and rate of progression.
The earlier the age of onset, the greater the impact on motor function. Consequently, children who show symptoms at birth or in infancy typically have the lowest level of functioning (type 1), followed by children (types 2 and 3), teens or adults (type 4).
It is caused by a deficiency in the gene SMN1
SMN1 gene is the main responsible for the production of a protein called SMN.
If the levels of SMN protein are little in the body, our motor neurons will be damaged and will not be able to transmit impulses to the muscles leading to a reduction of the motor activity.
Muscles are not active and consequently they get smaller and weaker. All of the muscles of the body are affected, but usually the ones of the legs suffer from a higher degree of weakness than the ones of the arms. It is also rather common that the disease causes problems in the muscles needed to chew and swallow.
Depending on the type and the state of the disease (age), the symptoms are different. However, some of them are common.
Children are generally not able to walk
The ability to walk decreases slowly
Standing up and sitting down become gradually complicated
prone to get respiratory diseases
Skin sensitivity and reaction to sensory inputs are not damaged in SMA patients. Moreover, it is very often observed that SMA patients are communicative and mentally fit. Hence, they do not only need medical and attentive care, but they also would like to have an active role in social life, like all of us.
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