Spinal muscular atrophy (SMA) is a genetic disorder that attacks and breaks down motor neurons in the spinal cord. These motor neurons are what controls the movement of muscles in a person’s body, and when the motor neurons die, the muscles weaken. Spinal Muscular Atrophy is a serious disorder, and has been classified as the second leading cause of neuromuscular disease. While there is no cure for Spinal Muscular Atrophy, there is a lot of helpful information, including causes, symptoms, and treatments. Read on to find out more about how SMA affects children. 

Spinal Muscular Atrophy and Kids

  • Causes
  • Symptoms
  • Treatment

SMA Causes

Spinal muscular atrophy is a genetic disease which means that the illness is caused by abnormalities in DNA. These abnormalities are inherited from parents, and for a child to have SMA they have to inherit one SMA gene from each parent. It is possible for a child to have SMA when neither parent has symptoms. This is because the parents may be carriers of the gene, meaning they have one copy of the SMA gene and one normal gene, and for SMA to develop and have symptoms one person has to have both copies of the SMA gene. A child of parents who are both carriers of SMA has a 25 percent chance of having SMA, and the risk of the child having SMA goes up to 50 percent if one parent has SMA and one parent is a carrier. The risk of a child having SMA if both parents have SMA is 100 percent. If SMA runs in a family, it is important for both prospective parents to consider genetic testing to determine if they are carriers of SMA. 


  • DNA abnormalities
  • Parents may not have SMA symptoms
  • Genetic testing may be warranted

SMA Symptoms

There are three types of SMA and symptoms and life expectancy varies wildly depending on the type. Type 1 is the most severe type of SMA. Symptoms typically develop between birth and six months. A child may not be able to support their head or sit without help and have difficulty swallowing, but the most concerning symptom is weakness in the muscles that control breathing. Most children with Type 1 SMA do not live past two due to breathing problems. Type 2 SMA is considered moderate. Symptoms develop between six and eighteen months, mostly affect their legs, and they will not be able to walk unaided. Life expectancy for children with Type 2 ranges from childhood to adulthood. Type 3 SMA is the most mild and symptoms can develop anytime between eighteen months and adulthood. Children with Type 3 SMA are usually able to stand and walk unaided but may have challenges with stairs, running, and other more strenuous activities. Children with Type 3 SMA are likely to have a close to normal life expectancy. Type 4 SMA is the most rare and symptoms do not appear until adulthood, and muscle weakness and atrophy will develop slowly. 


  • Three types of SMA in kids
  • Type 4 is rare and occurs in adults
  • Life expectancy varies

SMA Treatment

While there is no cure for SMA, there are a variety of treatment options to help reduce symptoms. Treatment plans vary depending on severity of symptoms and type of SMA. There are two FDA approved medications to treat SMA: nusinersen (Spinraza) and onasemnogene abeparvovec-xioi (Zolgensma). Other treatment options to help reduce symptoms include special mouthpieces or a machine to aid in breathing, working with a nutritionist and possibly a feeding tube to ensure adequate nutrition, physical and occupational therapy to help gain muscle strength, and possibly devices like leg braces, walkers, or wheelchairs to aid in mobility.


  • There is no cure
  • Treatment medications are available
  • Treatments can help reduce symptoms