Spinal muscular atrophies (SMAs)
What is it?
What is it?
Spinal muscular atrophy (SMA) is a neuromuscular disease characterized by the progressive death of motor neurons, nerve cells located in the spinal cord that control the activity and survival of muscle fibers. There are at least three forms of SMA, of which form I is the most severe and affects about half of patients. In this case, in babies, signs of the disease appear already at birth or in the first months; these are severe and progressive signs of respiratory failure. Children with Form II, also called intermediate form, acquire the ability to sit on their own but cannot walk. These babies also often have respiratory complications and other signs such as scoliosis, but overall the form is much more stable. Form III is the least severe; it often begins after the first few years of life and is always associated with the ability to walk, although in some cases this ability may be lost later.
There are adult forms and distal forms of SMA.
Causes and risk factors
The classic form of SMA is caused by a defect in one of two genes, SMN1 and SMN2, which results in insufficient levels of a protein called SMN. The mode of transmission is autosomal recessive: parents are healthy carriers of the genetic defect and have a 25% chance of transmitting the disease to each of their children.
Only a few genes of adult and distal forms are known.
How is it diagnosed?
Diagnostic suspicion is based on very characteristic clinical signs and often on electromyography, which shows signs of neurogenic distress. Diagnostic confirmation is obtained by genetic analysis.
Suggested exams
How is it treated?
There is no definitive cure at this time, but numerous studies are underway to evaluate possible therapies that work at the genetic level or in an attempt to prevent motor neuron loss.
Where do we treat it?
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