Spinal Muscular Atrophy (Type 2)

Definition

Definition of Spinal Muscular Atrophy (Type 2)
A genetic disease in which loss of nerve cells in the spinal cord called motor neurons affects the part of the nervous system that controls voluntary muscle movement.

Symptoms

Symptoms of Spinal Muscular Atrophy (Type 2)
Weakness is most severe in muscles closest to the center of the body, such as those of the shoulders, hips, thighs and upper back. Respiratory muscles can also be involved. Spinal curvature often develops.

Causes

Causes of Spinal Muscular Atrophy (Type 2)
A deficiency of a motor neuron protein called SMN, for survival of motor neurons, resulting from a faulty gene on chromosome 5.

Diagnosis

Diagnosis of Spinal Muscular Atrophy (Type 2)
Very severe SMA (type 0/I) can be sometimes evident before birth - reduction in foetal movement in the final months of pregnancy; else, it manifests within the first few weeks or months of life when abnormally low muscle tone is observed (the "floppy baby syndrome").
Further, for all SMA types,

1. Patient will present hypotonia associated with absent reflexes
2. Electromyogram will show fibrillation and muscle denervation
3. Serum creatine kinase may be normal or increased
4. Genetic testing will show bi-allelic deletion of exon 7 of the SMN1 gene - this is conclusive of the disease.

Treatment

Treatment of Spinal Muscular Atrophy (Type 2)
There is no known cure for spinal muscular atrophy type 2.

Prognosis

Prognosis of Spinal Muscular Atrophy (Type 2)
Generally, patients tend to deteriorate over time, but prognosis varies with the SMA type and disease progress which shows a great degree of individual variability.

The majority of children diagnosed with SMA type 0/I do not reach the age of 10, recurrent respiratory problems being the primary cause of morbidity. With proper care, milder SMA type 2 cases have lived into adulthood.

Prevention

Prevention of Spinal Muscular Atrophy (Type 2)
Consult with your doctor.