What does SMA mean in CLINICAL MEDICINE

Types of SMA

There are several different types of SMA, which are classified based on the age of onset and the severity of symptoms. The most common types of SMA are:

• Type 1 SMA (infantile SMA): This is the most severe type of SMA, and it typically affects infants before 6 months of age. Infants with type 1 SMA have severe muscle weakness and difficulty breathing and swallowing. They may never be able to sit or stand, and they often die before the age of 2.
• Type 2 SMA (intermediate SMA): This type of SMA affects infants and toddlers between 6 and 18 months of age. Children with type 2 SMA have less severe muscle weakness than children with type 1 SMA, but they may still have difficulty walking and breathing. They may also have scoliosis and other orthopedic problems.
• Type 3 SMA (juvenile SMA): This type of SMA affects children over the age of 18 months. Children with type 3 SMA have mild to moderate muscle weakness, and they may be able to walk and run. However, they may have difficulty with stairs and other activities that require strength.
• Type 4 SMA (adult SMA): This type of SMA affects adults in their 20s or 30s. People with type 4 SMA have mild muscle weakness, and they may not experience any symptoms until later in life.

Causes of SMA

SMA is caused by a mutation in the SMN1 gene. The SMN1 gene is located on chromosome 5, and it is responsible for producing the survival motor neuron (SMN) protein. SMN is essential for the health and function of motor neurons. Mutations in the SMN1 gene lead to a deficiency of SMN protein, which causes the motor neurons to die.

Symptoms of SMA

The symptoms of SMA vary depending on the type of SMA. However, some common symptoms include:

• Muscle weakness
• Difficulty walking, standing, and sitting
• Difficulty breathing and swallowing
• Scoliosis and other orthopedic problems
• Speech problems
• Fatigue
• Respiratory problems
• Feeding difficulties
• Muscle twitches and tremors

Diagnosis of SMA

SMA is diagnosed based on a physical examination and a genetic test. The genetic test can confirm the diagnosis of SMA and identify the specific mutation in the SMN1 gene.

Treatment of SMA

There is no cure for SMA, but there are treatments that can help to improve symptoms and slow the progression of the disease. These treatments include:

• Physical therapy: Physical therapy can help to strengthen muscles and improve range of motion.
• Occupational therapy: Occupational therapy can help to improve fine motor skills and daily living skills.
• Speech therapy: Speech therapy can help to improve speech and communication skills.
• Respiratory therapy: Respiratory therapy can help to improve breathing.
• Nutritional support: Nutritional support can help to ensure that people with SMA are getting the nutrients they need.
• Medications: There are several medications that can be used to treat SMA, including:
  • Nusinersen (Spinraza): Nusinersen is a medication that increases the production of SMN protein. It is approved to treat all types of SMA.
  • Risdiplam (Evrysdi): Risdiplam is a medication that increases the production of SMN protein. It is approved to treat types 1, 2, and 3 SMA.
  • Onasemnogene abeparvovec-xioi (Zolgensma): Zolgensma is a gene therapy that replaces the mutated SMN1 gene with a healthy copy of the gene. It is approved to treat type 1 SMA.