juvenile spinal muscular atrophy is an uncommon autosomal recessive disorder of the lower motor neurones
onset occurs between 2 and 17 years. It is characterised by wasting and weakness of proximal limb muscles. The deep tendon reflexes are decreased or absent. Fasciculations of the tongue may be occur
children and adults with type 3 SMA, also referred to as Kugelberg-Welander disease, are able to walk unassisted at some point during their lifetime
present with progressive proximal weakness of the legs more than the arms
leg weakness may necessitate the need of a wheelchair at some point
unlike, type 2, these individuals are mostly spared the comorbities of scoliosis and have little or no respiratory muscle weakness
cognition and life expectancy are not altered in this group
Notes:
term spinal muscular atrophy (SMA) refers to a group of genetic disorders all characterized by degeneration of anterior horn cells and resultant muscle atrophy and weakness
most common SMA, accounting for over 95% of cases, is an autosomal recessive disorder that results from a homozygous deletion or mutation in the 5q13 survival of motor neuron (SMN1) gene
clinical severity of SMA correlates inversely with SMN2 gene copy number and varies from an extreme weakness and paraplegia of infancy to a mild proximal weakness of adulthood
Reference;
Sugarman EA, et al. Pan-ethnic carrier screening and prenatal diagnosis for spinal muscular atrophy: clinical laboratory analysis of >72,400 specimens. Eur J Hum Genet. 2012; 20(1):27–32.
Annotations allow you to add information to this page that would be handy to have on hand during a consultation. E.g. a website or number. This information will always show when you visit this page.