Spinal Muscular Atrophy Type II (SMA Type II) is a genetic neuromuscular disorder characterized by progressive muscle weakness and atrophy primarily affecting the muscles responsible for movement. This condition is caused by mutations in the survival motor neuron 2 (SMN2) gene, leading to a deficiency in the production of the survival motor neuron (SMN) protein that is essential for the proper functioning of motor neurons.
Individuals with SMA Type II typically develop symptoms during infancy or early childhood. The hallmark feature of this condition is muscle weakness, initially observed in the lower limbs, which may later progress to involve the upper limbs as well. As the disease progresses, affected individuals experience difficulty in performing activities that require motor control, such as walking, sitting upright, or gripping objects. They may also exhibit muscle tremors and respiratory complications.
SMA Type II is considered an intermediate form of spinal muscular atrophy, lying between the more severe Type I, which usually manifests within the first few months of life, and the milder Type III, which usually starts in later childhood or early adulthood.
There is currently no cure for SMA Type II, but various medical interventions and therapies can help manage symptoms and improve quality of life. These may include physical therapy, respiratory support, assistive devices, and the management of associated complications like scoliosis. Additionally, recent advances in genetic treatments, such as the use of gene therapy and disease-modifying drugs, have shown promise in slowing the progression of SMA Type II.
