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Adult Spinal Muscular Atrophy (SMA)
Definition - 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.
Cause - A deficiency of a motor neuron protein called SMN, for survival
of motor neurons, resulting from a faulty gene on chromosome 5.
Onset - adulthood
Symptoms - Mild muscle weakness in muscles closest to the center of the
body, such as those of the shoulders, hips, thighs and upper back.
Progression - Variable disease progression. Relatively mild form of SMA
with little impact on life expectancy.
Most doctors now consider SMN-related SMA to be a continuum of
severity and prefer not to make rigid predictions about life expectancy or
weakness.
Inheritance - autosomal recessive; a faulty gene must be inherited from
each parent.
