Quick Facts about Spinal Muscular Atrophy


Spinal muscular atrophy (SMA), the number one genetic killer of children under the age of two, is a group of inherited and often fatal diseases that destroys the nerves controlling voluntary muscle movement, which affects crawling, walking, head and neck control, and even swallowing.


SMA is one of the most prevalent genetic disorders.

One in every 6,000 babies is born with SMA. Of children diagnosed before age two, 50 percent will die before their second birthday.
SMA can strike anyone of any age, race or gender.

One in every 40 people carries the gene that causes SMA. The child of two carriers has a one in four chance of developing SMA.



Type 1, or Werdnig-Hoffman Disease, is the most severe form of SMA. Children with Type I tend to be weak and lack motor development, rendering movement difficult. Children afflicted with Type I cannot sit unaided and have trouble breathing, sucking and swallowing. Type I SMA strikes infants between birth and six months.

Type II is slightly less severe. Type II patients may be able to sit unaided or even stand with support and usually do not suffer from feeding and swallowing difficulties. However, they are at increased risk for complications from respiratory infections. Type II SMA affects infants between seven and 18 months old.


Type III, also known as Kugelberg-Welander Disease, is the least deadly form of childhood-onset SMA. Type III patients are able to stand, but weakness is prevalent and tends to eventually sentence its victims to a wheelchair. Type III SMA strikes children after the age of 18 months, but can surface even in adulthood.


Type IV is the adult form of the disease in which symptoms tend to begin after age 35. Symptoms usually begin in the hands, feet and tongue, and spread to other areas of the body.



Adult Onset X-Linked SMA, also known as Kennedy's Syndrome or Bulbo-Spinal Muscular Atrophy, occurs only in men. Facial and tongue muscles are noticeably affected. In addition, these men also often have breast enlargement known as gynecomastia.  Like all forms of SMA, the course of the disease is variable, but in general tends to progress slowly.

SMA does not affect sensation and intellectual activity in patients. It commonly is observed that patients with SMA are unusually bright and sociable.


May 24, 2001 -- Scientists have found evidence suggesting that the severity of spinal muscular atrophy (SMA) may be ameliorated by common vitamins.   

The findings by researchers at the University of Pennsylvania School of Medicine, which are to be published Thursday in the journal Molecular Cell suggest that folic acid and Vitamins B12 may limit the severity of symptoms that afflict SMA patients. 

"We are not suggesting that this is a cure. But it may help," said Gideon Dreyfuss, PhD, Isaac Norris Professor of Biochemistry and a Howard Hughes Medical Institute Investigator at Penn, and principal author of the study.


August 24, 2000, - A significant breakthrough in identifying a treatment for Spinal Muscular Atrophy is being announced by an International team of researchers. The research, funded in part by Families of SMA, helps to identify what types of therapeutic approaches may be successful.



March 22, 2000 -- The group of J. Melki (French National Institute of Health and Medical Research, INSERM), publish the creation and characterization of a mouse model of SMA, a frequent neuromuscular disease characterized by degeneration of neurons of the spinal cord.   

Dr. Melki's mouse model closely resembles a type II/III phenotype. This mouse model will allow researchers to continue to study SMA at a molecular level. It will also be used to identify and test therapeutic strategies and the effectiveness of compounds discovered in the high-throughput drug screening.




In 1999, investigators at The Ohio State University replicated SMA in a mouse model. The researchers have demonstrated that when the mice have high amounts of the SMN2 gene, which is present in all human SMA patients, the SMA phenotype is corrected and they develop normally. These findings support the conclusion that large amounts of the protein could act to prevent the damage caused by SMA or even reverse the impact of the disease.