Did you know that 1 in every 40 people carries the abnormal gene that causes SMA? August is the month of Spinal Muscular Atrophy Awareness, and many are raising awareness and educating others about SMA.
What is Spinal Muscular Atrophy (SMA)?
Spinal Muscular Atrophy is the leading genetic cause of death for many babies under the age of two years old. SMA is mainly caused by a mutation in the survival motor neuron gene 1 (SMN1). This gene produces a protein that is critical to the function of the nerves that control our muscles.
Types of SMA
SMA type I (Werding – Hoffman disease or infantile-onset SMA) – this type occurs when a child is around 6 months old. Symptoms that may occur during this type of SMA are diminishing limb movements, lack of tendon reflexes fasciculations, tremors, swallowing and feeding difficulties, and impaired breathing.
SMA type II (Intermediate form) – this type mainly occurs in children who are between the ages 8 and 18 months of age. Children at this stage may be able to sit however, they are unable to stand or walk by themselves. Some have respiratory complications, which includes an increase in respiratory infections.
SMA type III (Kugelberg - Welander disease) - this type normally occurs from the ages between 2 and 17 years old. Symptoms that may occur during this type of SMA are abnormal movement of the limbs, difficulty running, climbing steps and a fine involuntary quivering with the fingers. Complications that can occur are scoliosis
SMA type IV (adult onset) - this type of SMA is much less common than types one to three. Adults are usually diagnosed with SMA type 4 in their second or third decade of life, usually after the age of 35, although some may have symptoms as early as 18 years of age.
SMA is caused by the defect in the gene SMN1. This gene makes protein that is important for the survival of motor neurons. Without this gene, nerve cells cannot properly function and eventually die. This will often lead fatal muscle weakness.
Many children can be diagnosed with SMA by taking a blood test. The blood test will detect whether there are any deletions or mutations of the SMN1 gene. Genetic tests are also available for chromosome 5-related SMA and for some of the other forms of SMA.
Currently, there is no cure for SMA. Nevertheless, many children use treatments such as muscle relaxants to help them manage symptoms and to prevent complications.