Spinal Muscular Atrophy (SMA) is a genetic disorder that affects the motor neurons in the spinal cord, leading to muscle weakness and atrophy. It is a rare condition that primarily affects infants and young children, but can also manifest in adulthood. SMA is caused by a mutation in the survival motor neuron 1 (SMN1) gene, which is responsible for producing a protein essential for the survival of motor neurons.
There are several synonyms or alternative names used to refer to Spinal Muscular Atrophy:
- Werdnig-Hoffmann disease: This term is often used to describe the most severe form of SMA, which presents in infancy and leads to significant muscle weakness and respiratory difficulties.
- Kugelberg-Welander disease: This term is used to describe a milder form of SMA that typically manifests later in childhood or adolescence. It is characterized by progressive muscle weakness and may have a slower progression compared to other forms of SMA.
- Infantile spinal muscular atrophy: This term specifically refers to SMA that presents in infants, typically within the first few months of life. It is often associated with significant muscle weakness, respiratory problems, and developmental delays.
- Proximal spinal muscular atrophy: This term is used to describe SMA that primarily affects the proximal muscles, which are the muscles closer to the center of the body. It encompasses various forms of SMA, including Werdnig-Hoffmann disease and Kugelberg-Welander disease.
It is important to note that while these terms are used interchangeably, they all refer to the same underlying condition, Spinal Muscular Atrophy. The severity and age of onset may vary, but the fundamental genetic cause remains the same.