Understanding Type 4
Spinal Muscular Atrophy (SMA)
Type 4 Spinal Muscular Atrophy (SMA), also known as adult-onset SMA, is a milder form of SMA that typically manifests later in life, usually during adolescence or adulthood. It is a genetic disorder that affects the motor neurons, resulting in muscle weakness and motor function impairments.
Individuals with Type 4 SMA experience a gradual onset of symptoms. They may notice muscle weakness, particularly in the proximal muscles (closest to the center of the body), such as the hip and shoulder muscles. The weakness may progress slowly over time, but individuals with Type 4 SMA often maintain the ability to walk independently throughout their lives.
Type 4 SMA is caused by mutations in the survival motor neuron 1 (SMN1) gene, leading to a deficiency of the survival motor neuron (SMN) protein. The reduced levels of this protein affect the functioning of motor neurons, resulting in the muscle weakness and motor impairments observed in Type 4 SMA.
Diagnosing Type 4 SMA involves clinical evaluation, genetic testing to identify mutations in the SMN1 gene, and sometimes electromyography (EMG) to assess muscle and nerve function.
The progression of Type 4 SMA is typically slow, and individuals with this form of SMA often have a near-normal life expectancy. They may experience varying degrees of muscle weakness and may benefit from physical therapy or other supportive measures to manage symptoms and optimize function.
Type 4 SMA can present unique challenges in adulthood, but individuals with this form of SMA often lead fulfilling lives, pursuing careers, and participating in various activities with appropriate accommodations