What is Spinal Muscular Atrophy Disease?
Spinal Muscular Atrophy, also known as SMA is a series of genetic illnesses in which motor neurons-nerve cells in the brain stem and spinal cord that govern vital skeletal muscle activities like speaking, walking, breathing, and swallowing are gradually destroyed, resulting in muscle weakening and atrophy. The arms, legs, chest, face, throat, and tongue are all controlled by motor neurons. When the signals between motor neurons and muscles are disrupted, the muscles gradually weaken, wither away, and develop twitching.
Causes of SMA
Defects in both copies of the survival motor neuron 1 gene (SMN1) on chromosome 5q generate the most prevalent form of SMA. This gene generates the survival motor neuron (SMN) protein, which keeps motor neurons healthy and functioning normally. Individuals with SMA have low amounts of the SMN protein, which causes motor neuron death in the spinal cord, resulting in skeletal muscle weakness and wasting. The trunk, upper leg, and arm muscles are frequently weaker than the muscles of the hands and feet.
Changes in the same genes cause several kinds of spinal muscular atrophy. Mutations in other genes, such as the VAPB gene on chromosome 20. The DYNC1H1 gene on chromosome 14, the BICD2 gene on chromosome 9, and the UBA1 gene on the X chromosome cause less prevalent forms of SMA. The kinds differ in terms of initial age and severity of muscle weakness, however, there is some overlap.
When parents or caregivers observe symptoms of SMA in a child, they frequently seek medical help. A doctor will do a thorough medical examination, as well as family history and a physical examination. They’ll examine the muscles for floppy or flaccidity, as well as deep tendon reflexes and tongue muscle twitching.
Tests for diagnosing SMA may include:
- blood tests
- a muscle biopsy
- genetic tests amniocentesis or chorionic villus sampling during gestation
- electromyography (EMG)
EMG can be used to examine the health of muscles and the nerve cells that regulate them, known as motor neurons. The doctor can evaluate the foetus in the womb via amniocentesis or chorionic villus sample.
SMA genetic screening at birth is recommended in several jurisdictions. If the illness is detected early enough, it may be possible to cure it before symptoms arise.
Progression of SMA
In chromosome 5-related SMA, the later symptoms show and the more SMN protein there is, the milder the disease is projected to be. While newborns with SMA used to seldom live longer than two years. Most doctors now see SMN-related SMA as a continuum and prefer not to make hard predictions regarding life expectancy or weakening based solely on the age of start. The most common genetic cause of infant mortality is SMA.