Spinal Muscular Atrophy is an autosomal recessive genetic disease. In order for a child to be affected by SMA, both parents must be carriers of the abnormal gene and both must pass this gene on to their child. Although both parents are carriers, the likelihood of a child inheriting the disorder is 25%, or 1 in 4. Your chance of carrying the gene for SMA is 1/40.

(SS) Not affected Not a carrier

(Ss) Not affected SMA carrier

(ss) SMA affected SMA carrier

(Ss) x (Ss)			Two people carrying the gene for SMA have children. Each parents will pass one part of each gene to their offspring as shown in the diagram. 2 of 4 children, or 50% of the offspring, will be carriers of SMA - silently passing the mutated gene on for generations. 1 of 4 children (25%) will be affected by SMA for life and will pass the mutated gene on to 100% of their children if they live long enough to reproduce. Know your genetics and your personal risks in the game of life.
	S	s
S	SS	Ss
s	Ss	ss

	For every fourty people you see in a day, at least one of them is carrying the gene for SMA.
	It could be you.

Spinal Muscular Atrophy is a motor neuron disease. Motor neurons affect the voluntary muscles that are used for activities such as crawling, walking, head and neck control, and swallowing. It is a common disorder: affecting approximately 1 in 6,000 babies born. One in 40 people are genetic carriers. An individual with SMA has a missing or mutated gene called Survival Motor Neuron 1 (SMN1) that produces protein in the body called SMN protein. This protein deficiency has its most severe affect on motor neurons. Motor neurons are nerve cells in the spinal cord which send out nerve fibers to the muscles throughout the body. Without this protein, nerve cells atrophy, shrink, and eventually die, resulting in muscle weakness.