What is SMA?

A Brief Rundown of SMA

This is the neurological disorder that has put Little David in a wheelchair from the age of 4  to where he is today in his journey with SMA and the treatments he has had along the way. Make sure you read about this young man’s situation and his struggles to date. More details can be found on the first page of this very site entitled SpecialNeedsPeople.Click on the link if you didn’t get a chance to read Little David’s adventure.

SMA is an abbreviation for Spinal Muscular Atrophy

SMA is a neurological disorder. It is not contagious. SMA is a genetic disease that attacks nerve cells called motor neurons in the spinal cord and the brain stem. When the motor neurons die, this cuts off communication to the muscles which then get progressively weaker and atrophy due to lack of use. Of course, being a genetic disease, SMA runs in families. As you can imagine, atrophied muscles affect walking, crawling, swallowing, breathing, head and neck control. The level of muscle control varies due to a number of factors from the age of onset to the level of intensity of the disorder. There are basically 4 primary types of the disorder although, like most disorders, there are variances but we can pretty accurately divide the disorder into 4 basic types.

Types of SMA

Type I – Type I is a severe form of SMA that is evident at birth or within the first few months of life. Infants diagnosed with Type I are developmentally delayed. Most are unable to support their head or sit unassisted. Children with this type often have breathing and swallowing problems that often lead to choking or gagging.

Type II – Type II is characterized by muscle weakness that develops in children between ages 6 and 12 months. Children with type II can sit without support, although they may need help getting to a seated position. Individuals with this type of SMA cannot stand or walk unaided.

Type III – Type III has somewhat milder features and usually develop between early childhood and adolescence. Individuals with type III  can usually stand and walk unaided. Most of the time walking and climbing stairs may become increasingly difficult. Many affected individuals will require wheelchair assistance later in life.

Type IV – Type IV often occurs after age 30. People with type IV usually experience mild to moderate muscle weakness, tremors, twitching, or mild breathing problems. Usually, the muscles close to the center of the body, such as the upper arms and legs, are affected.

Little David is basically in the Type III range. He was able to walk, although unevenly, at an early age but by about the age of 4 he just let go of his little walker and sat down.

Spinal Muscular Atrophy Causes an Exceptionally High Infant Mortality Rate

SMA is the leading heritable cause of infant mortality worldwide. It is a neurodegenerative disorder that presents as progressive muscle wasting and loss of motor function. As motor nerves are located in the spinal cord, a vast decrease in muscle control for several activities (such as breathing, walking, head and neck control, swallowing) occurs. SMA is an autosomal recessive disorder caused by deletion of the survival motor neuron gene 1 (SMN1).

SMA Facts

  • 1 in 6,000 births is an SMA baby
  • 1 in 40 adults is a carrier of the gene mutation that causes SMA
  • The child of 2 carriers has a 1-in-4 chance of having SMA
  • ​7.5 million Americans are carriers
  • There is now an FDA-approved drug for SMA called Spinraza created by a wonderful company called Biogen.

Over the last few years there has been a lot of promising research into finding a Cure for SMA. Little David is in the first year of his treatment. He is still disabled but says he can feel a small increase in his physical strength. He says he gets the urge to stand up but at least at this point is still too weak.


Comments on this SMA article

If you have SMA or a friend, a loved one has SMA  please leave us your thoughts below.  If you found this interesting, or even way out in left field, Please comment below. We All benefit from every comment or suggestion and it only takes a minute to let us know what YOU think. Thank You!

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About David Kennedy

I am a retired Senior Development Engineer for Hughes Aircraft Company. I retired from Hughes In 1997 and moved to Phoenix with my young daughter to be with my two older sons attending Arizona State University. I am a former member of the U.S. Air Force where I was an active member of the 95th Fighter Interceptor Squadron.
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