Spinal Muscular Atrophy (SMA) Types I, II, and III belong to a group of hereditary diseases that cause weakness and wasting of the voluntary muscles in the arms and legs of infants and children. The disorders are caused by an abnormal or missing gene known as the survival motor neuron gene (SMN1), which is responsible for the production of a protein essential to motor neurons. Without this protein, lower motor neurons in the spinal cord degenerate and die. The type of SMA (I, II, or III) is determined by the age of onset and the severity of symptoms. Type I (also known as Werdnig-Hoffman disease, or infantile-onset SMA) is evident at birth or within the first few months. Symptoms include floppy limbs and trunk, feeble movements of the arms and legs, swallowing difficulties, a weak sucking reflex, and impaired breathing. Type II (also known as juvenile SMA, intermediate SMA, or chronic SMA, has an onset between 6 and 18 months. Legs tend to be more impaired than arms. Children with Type II are usually able to sit without support if placed in position. Some may be able to stand or walk with help. Type III (also called Wolhlfart-Kugelberg-Welander disease, or mild SMA) can begin as early as the toddler years or as late as adolescence. Children can stand alone and walk, but may have difficulty getting up from a sitting position.
There is no cure for SMA. Treatment consists of managing the symptoms and preventing complications.
The prognosis is poor for babies with SMA Type I. Most die within the first two years. For children with SMA Type II, the
prognosis for life expectancy or for independent standing or walking roughly correlates with how old they are when they first
begin to experience symptoms - older children tend to have less severe symptoms Children with onset after 18 months are often
able to walk and are fully functional for years before they need assistance. They may have a normal life expectancy.
The Spinal Muscular Atrophy Project is an NINDS funded collaborative program focused on the development of drug therapies
for the treatment of SMA. Experts from industry, academia, NINDS, and the U.S. Food and Drug Administration guide the program.
The Project is accelerating the research process by identifying drugs already in use that increase the level of SMN protein
in cultured cells, which are then used as potential leads for further drug discovery and clinical testing.
FightSMA/Andrew's Buddies 1807 Libbie Avenue Suite 104 Richmond, VA 23226 heatherlennon@fightsma.com http://www.fightsma.org Tel: 804-515-0080 Fax: 804-515-0081 |
Families of Spinal Muscular Atrophy P.O. Box 196 Libertyville, IL 60048-0196 info@fsma.org http://www.curesma.org Tel: 800-886-1762 Fax: 847-367-7623 |
Spinal Muscular Atrophy Foundation 888 Seventh Avenue Suite 400 New York, NY 10019 info@smafoundation.org http://www.smafoundation.org Tel: 877-FUND-SMA (877-386-3762) 646-253-7100 Fax: 212-247-3079 |
Muscular Dystrophy Association 3300 East Sunrise Drive Tucson, AZ 85718-3208 mda@mdausa.org http://www.mda.org Tel: 520-529-2000 800-344-4863 Fax: 520-529-5300 |
Prepared by:
Office of Communications and Public Liaison
National Institute of Neurological Disorders and Stroke
National Institutes of Health
Bethesda, MD 20892
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Last updated July 09, 2008