Spinal Muscular Atrophy has been discussed, including its symptoms and treatments, in a previous article. Now let’s take a look at the gene that causes this debilitating hereditary disease. The Spinal Muscular Atrophy gene is often diagnosed as early as 6 months of age. Also known as the SMN1 gene, it does not relent as it starts from a young age and progresses until death. While only Type 1 is fatal, the symptoms progressively lead to lack of mobility and normal living becomes difficult.

Defect In SMN1 Gene Is Hereditary

The biggest key to the Spinal Muscular Atrophy gene is that it is inherited. It comes primarily from the genes passed on by parents. In fact, cureSMA comments that “SMA is an autosomal recessive genetic disorder. This means that, generally, both parents must pass on the mutation for the child to have SMA.” (2)

The Muscular Dystrophy Association (MDA) reports that “the most common form of SMA (types 1-4) is caused by a defect (mutation) in the SMN1 gene on chromosome 5.”(1) Every person carries two of these genes (one on each chromosome), and a defect in one leads to the disorder occurring, usually at birth. The defect is caused by a mutation resulting from the loss of nerve cells in the spinal cord. This loss likely occurs from a lack of the motor neuron protein SMN, for survival of motor neuron.

Inoperative Spinal Muscular Atrophy Gene Can Be Debilitating

In our earlier article, What Is Spinal Muscular Atrophy? we discuss how it is a hereditary disorder that causes damage to lower motor nerves that control:

  • Breathing
  • Swallowing
  • Walking
  • and other basic functions

The level of debilitation from a defective SMN1 gene varies based on how much SMN1 protein is made available from a neighboring SMN2 gene. The more the protein produced by SMN2, the milder the symptoms will be for the afflicted. The disease can also be affected by modifying proteins, plastin3 and ZPR1, that determine the development of biological pathways important in reducing disease onset and progression.

In a previous article, Can Physical Therapy Improve SMA Disease?, we discussed how “low levels of the SMN1 protein cause poor muscle control. This can make it hard to walk, talk, eat, or perform other common and necessary tasks.” Unfortunately, there is no cure for a defective Spinal Muscular Atrophy gene, but there are treatments to lessen the symptoms’ hold on one’s life.

Mutated SMN1 Gene Works Like A Trojan

Spinal muscular atrophy is genetic, meaning it is passed down from parent to child. It also acts like the fable Trojan Horse, hiding behind a gateway only to attack when the host lacks the necessary defense mechanism to cure it. This defense is the SMN1 protein produced, as we said above, by both the SMN1 gene and sometimes the SMN2 gene. While it may seem sneaky since it is not diagnosed until at least 6 months after birth, tests can be done in utero to determine the effectiveness of SMN1 protein development within a fetus.

Defective Spinal Muscular Atrophy Gene Is Not A Death Sentence

While those children diagnosed early with SMA Type 1 have a life expectancy of fewer than 18 months, the three other types of SMA offer promise for a more normal life. With the rise of treatments available, SMA-afflicted children can grow well into adulthood.

The latest in gene therapy may also show promise for those with a defective SMN1 gene because the healthy SMN2 gene can be stimulated or replicated to counteract faulty protein production better. Furthermore, the mere existence of this sister gene, SMN2, can provide necessary SMN protein naturally that will lessen the effects of SMA on children as they grow.

Should the SMN1 Gene Be Tested?

Overall, the Spinal Muscular Atrophy gene is a critical component of our chromosomes that can be passed on by unknowing parents leading to a less than ideal life for their child. A parent must think deeply about their child’s needs when afflicted with SMA and whether they can meet them for the duration of life.  But, you’re never alone.  There is a lot more support for this condition now than ever before.  Talk


(1) Spinal Muscular Atrophy – Causes/Inheritance


(2) SMA Genetics | Cure SMA


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