What does SMA mean in HEALTHCARE

Causes of SMA

SMA occurs due to mutations in the SMN1 gene, located on chromosome 5q. This gene produces a protein called Survival of Motor Neuron (SMN) protein, which is crucial for the maintenance and survival of motor neurons. The mutation either reduces the production of SMN protein or leads to the production of a non-functional protein.

Types of SMA

There are four main types of SMA, classified based on the age of onset and the severity of symptoms:

• Type 1 (Infantile SMA): This is the most severe type, with onset before 6 months of age. Infants with SMA Type 1 experience severe muscle weakness, breathing difficulties, and difficulty swallowing. They often require ventilators and feeding tubes.
• Type 2 (Intermediate SMA): Onset occurs between 6 and 18 months of age. Children with SMA Type 2 have less severe muscle weakness compared to Type 1, but they still have difficulty walking and may experience respiratory problems.
• Type 3 (Juvenile SMA): Onset occurs after 18 months of age. Individuals with SMA Type 3 have milder muscle weakness and can walk, but they may experience fatigue and difficulty with fine motor skills.
• Type 4 (Adult SMA): Onset occurs in adulthood, usually after the age of 30. People with SMA Type 4 experience progressive muscle weakness, particularly in the legs, arms, and hands. They may also have difficulty breathing and swallowing.

Symptoms of SMA

The symptoms of SMA vary depending on the type and severity of the condition. Common symptoms include:

• Muscle weakness and atrophy: This is the hallmark symptom of SMA, affecting the limbs, trunk, and respiratory muscles.
• Difficulty breathing: Due to weakness in the respiratory muscles, individuals with SMA may experience difficulty breathing and require respiratory support.
• Difficulty swallowing: Weakness in the muscles responsible for swallowing can lead to difficulties with eating and drinking.
• Joint contractures: As muscles weaken, joints can become stiff and contracted, limiting mobility.
• Scoliosis: Weakness in the back muscles can lead to a curvature of the spine (scoliosis).

Diagnosis of SMA

SMA is diagnosed through a combination of physical examination, genetic testing, and electromyography (EMG). Genetic testing confirms the presence of mutations in the SMN1 gene. EMG measures the electrical activity of muscles and nerves, which can help assess the severity of muscle weakness.

Treatment for SMA

Currently, there is no cure for SMA. However, there are treatments available to manage the symptoms and improve the quality of life for individuals with this condition. These treatments include:

• Nusinersen (Spinraza): A medication injected into the spinal cord that increases SMN protein levels.
• Zolgensma: A gene therapy that replaces the mutated SMN1 gene with a functional copy.
• Risdiplam (Evrysdi): An oral medication that increases SMN protein levels.
• Physical therapy: To improve muscle strength and mobility.
• Occupational therapy: To enhance independence with daily activities.
• Respiratory support: To assist with breathing difficulties.