One of the most poignant parts of the two-day series was when , Leo, at eleven days of age. Leo died of a neuromuscular disease called Spinal Muscular Atrophy (SMA). SMA is a disease where the nerve cells that control motor neurons are damaged. SMA belongs to a group of genetic 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), found on chromosome 5, which is responsible for the production of a protein (called SMN protein) essential to motor neurons. Without this protein, lower motor neurons in the spinal cord degenerate and die.
According to :
- SMA is one of the most prevalent genetic disorders.
- One in every 6,000 babies is born with SMA.
- 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.
- 7.5 million Americans are carriers.
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. It has been postulated that physicist suffers from this form of the disease and not amyotrophic lateral sclerosis (Lou Gehrig's Diease) as is widely believed.
Is there any treatment?
There is no cure for SMA. Treatment consists of managing the symptoms and preventing complications.
What is the prognosis?
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. Mental functioning in all groups remains normal.
What research is being done about SMA?
Several basic science studies are looking at ways to stimulate the production of the SMN protein from the SMN2 gene, a gene that is almost identical to SMN1. Most children with SMA have functional SMN2 genes. Researchers are beginning to test (in animal models) chemical compounds that have the potential to from the SMN2 gene.
Ongoing are testing the benefits in children of hydroxyurea, riluzole, valproic acid, and phenylbutyrate -- drugs that have promise in treating the symptoms of SMA. Researchers are following the trial participants to determine how well the drugs are tolerated, the optimal dosage, and the best mode of administration.
The Spinal Muscular Atrophy (SMA) Project is an NINDS-funded collaborative program focused on the development of drug therapies for the treatment of SMA. The program is guided by experts from industry, academia, NINDS and the FDA. 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.
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