Page 1 (0s)
Spinal muscular atrophy (SMA) is a rare neurological genetic disease that affects nerves and muscles and causes progressive muscle weakness and muscle wasting. due to loss of the lower motor neurons that control movement. It mostly affects infants and children but can also develop in adults. The most common form, accounting for 95% of SMA cases, is a proximal predominant autosomal recessive disease caused by a deletion or mutation of the SMN1 gene reduces the intracellular survival motor neuron protein levels , most likely by interfering with spliceosome assembly and the presence of copies of the transcriptionally inefficient SMN2 gene. The severity of the disease correlates with the amount of SMN protein present. People with type 1 SMA, with a life expectancy of 2 years, produce very little SMN protein. Patients cannot sit upright without support and ultimately lose the ability to breathe unaided. People with type 2 and 3 SMA, the intermediate and mild forms, produce greater amounts of SMN. Although their symptoms are less severe in comparison to the type 1 form, the disease does have life-changing effects..