What is spinal muscular atrophy?
Spinal muscular atrophy (SMA) is a neuromuscular disorder characterized by degeneration of the anterior horn cells of the spinal cord, leading to symmetrical muscle weakness and atrophy. SMA is the second most common lethal autosomal recessive disorder in Caucasians, after cystic fibrosis.
What causes spinal muscular atrophy?
Spinal muscular atrophy is caused by deletions/duplications of one or more sequences in the SMN1 and SMN2 gene. This disease is inherited in an autosomal recessive pattern, which means having both copies of the SMN1 gene in each cell have the mutations. The parents of an individual with an autosomal recessive condition are carriers of the condition which each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. Extra copies of the SMN2 gene are due to a random error when making new copies of DNA (replication) in an egg or sperm cell or just after fertilization.
What is this test for?
This test detects the copy number changes in exon 7 and 8 of the SMN1 and SMN2 genes which associated with spinal muscular atrophy.
Who should consider this test?
Factor(s) known to affect results