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Infantile Progressive Spinal Muscular Atrophy
(SMA, SMA1 or WH)
(Also known as SMA Type 1, Werdnig-Hoffman)
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
- Before birth to 6 months.
Symptoms - Generalized muscle
weakness, weak cry, trouble swallowing as well as sucking, and breathing
distress. Cannot sit without support.
Progression
- Can progress very rapidly with early childhood death. Most doctors, however,
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.
