Spinal muscular atrophy, or SMA, is a genetic disease that attacks nerve cells in the spinal cord. These nerve cells, known as motor neurons, communicate with the voluntary muscles in the body, such as those in the arms and legs. As more neurons are lost, muscles start to weaken and breathing, crawling, swallowing, and walking can become more difficult. It also can be difficult for those with SMA to control movements in their heads and necks. Though SMA runs in families, parents can exhibit no symptoms but still carry the gene. There are many types of SMA, and, according to the National Institute of Neurological Disorders and Stroke, the type of SMA is determined by the age of onset and the severity of symptoms. SMA Type I is evident at birth or within the first few months of a child being born. Symptoms may include difficulty swallowing, feeble movements of the arms and legs, loose limbs and trunk, impaired breathing, and a weak sucking reflex. SMA Type II is evident between the ages of six and 18 months, and the legs are typically more impaired than the arms. An early indicator may be a baby who is not crawling or walking. SMA Type III may be evident when a child reaches his or her toddler years, but sometimes does not appear until adolescence. When a child has SMA Type III, he or she may have trembling fingers and may experience difficulty getting up from a sitting position. Children with SMA Type II or Type III are at an increased risk of respiratory infections.
What causes SMA?
According to the Muscular Dystrophy Association, chromosome 5 SMA, the most common form of SMA, is caused by a deficiency of SMN, a motor neuron protein. This protein is necessary for normal motor neuron function, and a deficiency of SMN is caused by mutations on chromosome 5 in the SMN1 gene. Mutations in other genes may also cause SMA, and such cases are referred to as non-chromosome 5 SMA.
What are the symptoms of SMA?
There are various types of SMA, and the symptoms can vary depending on the type of SMA a person has. The following are some of the symptoms associated with the various types of SMA.
- Type 1: Type 1 is the most severe type of SMA. When a child is type 1, he or she may have difficulty supporting his or her head and sitting without help. Difficulty swallowing and weakness in the arms and legs may also occur. The muscles that control breathing also can be compromised when a child has type 1 SMA, and breathing problems can affect a child’s life expectancy.
- Type 2: Type 2 SMA typically affects the legs more than the arms. Type 2 SMA affects children between six and 18 months of age, and such kids may be able to sit, stand or walk with help.
- Type 3: The mildest form of SMA, type 3 may be referred to as juvenile SMA. Children with type 3 can often stand or walk without help, but they may have difficulty climbing stairs, getting up from a chair or running.
- Type 4: Type 4 SMA begins in adulthood, and men and women may experience muscle weakness, twitching or breathing problems. Physical therapy can help men and women better manage their symptoms, which typically only affect the upper arms and legs.
Recently the FDA approved an amazing new drug Spinraza to treat symptoms of SMA and prolong these life of individuals taking Spinraza. With a few injections, patients with SMA may be able to gain muscle strength and live longer by a year or more. It cost $125,000 an injection, and in the first two months one takes 4 injections in the spine. That’s half a million dollars for the first four shots. Subsequent costs for this possibly lifelong therapy are expected to be about $375,000 annually, with about three injections required each year. While this may seem extremely expensive the drug was developed to save lives, along with some resources available to help individuals requiring the drug. With coverage being more readily available to those effected the most, starting with SMA type I. Remember if you are trying to obtain Spinraza use every resource available at your disposal and educate yourself on the drug, available resources, and your healthcare. Don’t be afraid to ask questions and challenge your neurologist who would prescribe Spinraza along with your insurance representative, and if you have to, seek out a social worker for assistance. Be your own advocate. Take into account this drug has been developed and approved in a significantly short amount of time. Spinraza is for a relatively low percentage of the population, lots of money and resources were put into the development of this drug. For more information and resources go to SMAnewstoday.com. Remember to connect yourself with other individuals with SMA to share resources and connect with others who are going through the same thing you may be experiencing with SMA.
Parents can also learn more about SMA by visiting the Muscular Dystrophy Association online at www.mda.org & www.curesma.org