Spinal muscular atrophy (SMA) is an incurable autosomal recessive disease caused by a genetic defect in the SMN1 gene which codes SMN, a protein necessary for survival of motor neurons, and resulting in death of neuronal cells in the anterior horn of spinal cord and subsequent system-wide muscle wasting (atrophy).
The lifespan in SMA type I is seldom longer than 2 - 3 years. Survival time with type II is longer, but the disease kills most of those affected while they are still children. Children with type III disease may survive into early adulthood. However, people with all forms of the disease have worsening weakness and debility.
Through the concerted efforts of drug companies, government agencies, academic institutions, and advocacy groups, the SMA community has reached an exciting point where new therapeutics have entered clinical trials or are approaching trials in the near future.
Researchers treated SMA-affected mice with histone deacetylase (HDAC) inhibitors, commonly used in psychiatry and neurology as mood stabilizers and anti-epileptics and increasingly for cancer and inflammatory disease treatments, and found that the drug increased the levels of SMN protein in the muscles of the mice by targeting the genetic mutation.
Doctors have previously known that the disease targets the body’s nerve cells, causing those affected to have little or no control over their movements. Researchers at the University of Edinburgh conducted a study on mice, and found that the disease not only causes nerve damage, but also reduces the blood supply to muscle tissue.
Spinal muscular atrophy (SMA) is a collection of different muscle diseases. Grouped together, it is the second leading cause of neuromuscular disease. Most of the time, a person must get the defective gene from both parents to be affected. Approximately 4 out of every 100,000 people have the condition.
In the second study, the researchers treated mice with SMA with a class of drugs known as HDAC inhibitors.
It was found treatment increased the levels of the protein in muscle by targeting the genetic mutation.
Infants with SMA type I are born with very little muscle tone, weak muscles, and feeding and breathing problems. With SMA type III, symptoms may not appear until the second year of life.
Type 1 babies have floppy limbs and "flickering" tongues.
Type 2 is usually picked up when children are between six and 18 months old. Affected children are able to sit, but cannot walk.
Type 3 is the mildest form of the disease. Children are usually diagnosed over the age of two. Many have problems walking and may require a wheelchair.
It affects one in 6,000 births, but 50% of those with the most severe form die before the age of two.
Spinal muscular atrophy (SMA) - "floppy baby syndrome" - is the leading genetic cause of death in children.