Understanding Spinal Muscular Atrophy: Causes and Symptoms
Spinal muscular atrophy (SMA) is a genetic disorder affecting nerve signals to muscles, leading to muscle atrophy and weakness. It varies by age of onset, with more severe forms appearing in infants. Caused mainly by mutations in the SMN1 gene, SMA affects proximal muscles, causing mobility issues and, in some cases, respiratory problems. The disease is inherited but can also result from new genetic mutations, while sensory and mental functions remain normal.
Spinal muscular atrophy (SMA) is a hereditary disorder impacting the nervous system, specifically affecting the nerves responsible for voluntary muscle movement. The muscles lose their signals from nerves near the spinal cord, leading to muscle deterioration known as atrophy. The severity depends on the age at which symptoms appear; early onset results in more significant motor impairments. Infants with SMA often experience severe functional limitations.
Forms of SMA include Type 1 (severe in infants), and Types 2, 3, and 4 in children and adults, with higher motor function levels. SMA results mainly from mutations in the SMN1 gene, which encodes the essential survival of motor neuron protein. Deficiency in this protein causes motor neuron degeneration, primarily impacting proximal muscles like shoulders, hips, and thighs, leading to spinal curvature and difficulties with swallowing and breathing. Despite muscular weakness, sensory, mental, and emotional functions remain unaffected. SMA is inherited via mutations in both copies of the SMN1 gene, often inherited from carrier parents with no symptoms, or due to new mutations during early development.
