What is Spinal Muscular Atrophy (SMA)?

Spinal Muscular Atrophy (SMA) is the number 1 genetic killer of children under 2 years of age. It can strike a person anytime throughout their life - infant, toddler, teen or adult.

SMA is a group of inherited and sometimes fatal diseases that destroy the nerve cells (motor neurons) controlling voluntary movement, such as, crawling, walking, head and neck control, as well as swallowing and breathing. It affects the anterior horn cells located in the spine.

Facts About SMA

  • 1 in 40 people are carriers of the SMA gene.
  • 1 in every 6,000 live births is affected.
  • Over 25,000 people in the USA have SMA.
  • SMA does not discriminate when it comes to sex, age, race or ethnic background.
  • Generally both parents must carry the SMA gene to have a child affected by SMA.
  • There is a 1 in 4 chance of having a child with SMA if both parents carry the gene.
  • There is a 50% chance of having a child who carries the gene if both parents carry the gene.
  • There is a 25% chance of having a child who carries the gene if one parent carries the gene.

There are 4 types of SMA:

  • TYPE 1 (Werdnig-Hoffmann disease): Infantile; Most Fatal
  • TYPE 2: Strikes between 9 months to 2 years
  • TYPE 3 (Kugelberg-Welander disease): Juvenile; Can strike at any time between 18 months to 17 years
  • TYPE 4: Adult: Strikes as early as 18 years but usually after 35 years

More Information

For more detailed information on SMA as well a place for support, go to SMA Support.

To search for information or support for other rare diseases (if you are not yet sure of a diagnosis, or the diagnosis does not match SMA) go to Madison's Foundation.