SEODF

Understanding Type 1
Spinal Muscular Atrophy (SMA)

Type 1 Spinal Muscular Atrophy (SMA), also known as Werdnig-Hoffmann disease, is the most severe form of SMA after Type 0. It typically manifests within the first few months of life and is a genetic disorder characterized by progressive muscle weakness and limited motor function.

Infants with Type 1 SMA experience profound muscle weakness and hypotonia (low muscle tone) from an early age. Motor milestones such as sitting, crawling, and walking are often not achieved or are significantly delayed. Weakness in the muscles responsible for breathing and swallowing can lead to respiratory and feeding difficulties.

Type 1 SMA is caused by mutations in the survival motor neuron 1 (SMN1) gene, resulting in a deficiency of the survival motor neuron (SMN) protein. The absence or reduced levels of this protein lead to the degeneration and loss of motor neurons in the spinal cord and brainstem. The progressive loss of motor neurons contributes to the severe muscle weakness and motor impairments observed in Type 1 SMA.

Diagnosing Type 1 SMA involves clinical evaluation, genetic testing to identify mutations in the SMN1 gene, and sometimes electromyography (EMG) to assess muscle and nerve function.

Type 1 SMA significantly impacts an infant’s quality of life and is associated with a shortened life expectancy. Without intervention, life expectancy for infants with Type 1 SMA can range from a few months. In very rare cases and without treatment, some individuals may survive beyond the first year, but this is an exception rather than the norm.

Managing the challenges associated with Type 1 SMA requires specialized medical care and support. Families of affected individuals often demonstrate remarkable resilience and seek ways to optimize the child’s well-being.