Spinal Muscular Atrophy (SMA) Carrier Testing

This blood test is used to determine carrier status and prenatal diagnosis for spinal muscular atrophy.

Spinal muscular atrophy (SMA) is an autosomal recessive disease caused by deletions or, less often, point mutation(s) in the SMN1 gene, leading to a reduction in the amount of survival motor neuron (SMN) protein. SMA is characterized by the progressive degeneration of the lower motor neurons, leading to muscle weakness and, in the most common type, respiratory failure by age two.

Muscles responsible for crawling, walking, swallowing, and head and neck control are the most severely affected. SMA has been known as congenital axonal neuropathy, arthrogryposis multiplex congenita (prenatal SMA), Werdnig-Hoffmann disease (SMA type I), Dubowitz disease (SMA type II) and Kugelberg-Welander disease (SMA type III).