This document discusses spinal muscular atrophy (SMA). SMA is caused by a mutation in the SMN1 gene located on chromosome 5q13. This gene normally produces SMN proteins which are important for survival of motor neurons. In SMA, little to no SMN proteins are produced, motor neurons cannot function properly, and muscle weakness results. SMA presents in infants as weak muscles, breathing and feeding problems, and in children as worsening respiratory conditions and posture. Treatments focus on supportive care, physical therapy, and braces. SMA has an autosomal recessive inheritance pattern and affects 1 in 6000 people, though 1 in 40 are carriers.

2. SYMPTOMS
Infants:
• Very little/ weak muscles – often first noticed in
shoulders and legs
• Breathing and feeding problems
• Low head control
• Worsening muscle weakness
• Little movement
• Low muscle tone
Children:
• Respiratory conditions that are increasing in
severity
• Nasally speech
• Increasingly worse posture

3. TREATMENTS
• No prevention treatments
• Supportive Care is important to the patient
• Pay attention to the respiratory system
• Physical therapy to help with spine structure
and muscle and tendon strength
• Brace may be needed

4. LOCATION OF THE GENE AFFECTING THIS
DISORDER
The gene that causes this disorder is located in chromosome 5q13
and is known as survival motor neuron gene 1 (SMN1)
You can see in the diagram that the
gene that malfunctions causing SMA
Type 1 is located where is says “SMA
focus”

5. WHAT THE GENE SHOULD DO
• Produce SMN1 proteins-giving instructions to build SMN
proteins
• SMN proteins play a huge role in the survival of motor
neurons
• Motor neurons send impulses which stimulate nerve cells
WHAT HAPPENS IN SMA
• Little or no SMN1 proteins are produced
• Little or no SMN proteins are produced
• Motor neurons are not made and cannot send impulses
which stimulate nerve cells

6. INHERITANCE PATTERN
• It has autosomal recessive inheritance pattern
that means that it is a recessive gene so in
order to have the disease you have to have two
mutated genes.
• So one of your parents could have one gene
and not express it that means they are a carrier.
So their kids could inherit it though.
• There is often no family history of the disease.

7. PREVALENCE IN POPULATION
• 1 in 6000 people have the disease but 1
in 40 are carriers
• Affects all people of all races and
genders

8. BIBLIOGRAPHY
Board, A.D.A.M. Editorial. Spinal Muscular Atrophy. U.S. National Library of
Medicine, 1 Feb. 2012. Web. 15 Dec. 2012.
Overview | Spinal Muscular Atrophy | MDA." Muscular Dystrophy
Association. Muscular Dystrophy Association, n.d. Web. 18 Dec. 2012.
SMA in Laymen's Terms." SMA in Laymen's Terms. N.p., n.d. Web. 18 Dec.
2012.