Spinal muscular atrophy (SMA) is a severe and often fatal genetic disorder. It is the the most common inherited cause of infant death in children under the age of two. SMA affects the muscles needed for many essential functions, like breathing, eating, and movement. Individuals with SMA become progressively weaker (atrophy) and die. There is currently no treatment for SMA. To learn more about SMA, view or download the Fact Sheet.

Who Should Take It?

• All individuals of childbearing age, regardless of gender
• All individuals with a family history of genetic disorders
• All individuals with partners that are carriers of a genetic disorder
• Those considering in vitro fertilization
• Pregnant women

Why Clarity Genetics?

When testing, our laboratory analyzes all of the coding DNA in a gene to determine if any disease-causing pathogenic variants are present. By sequencing all of the coding DNA in a gene, instead of just a portion, we are able to offer the most accurate genetic testing available, regardless of your ethnicity. The majority of laboratories are only sequencing a portion of the gene, leaving room for error with missed pathogenic variants, especially when testing a variety of ethnicities. By sequencing the entire gene, Clarity Genetics testing eliminates the doubt in a negative result and drastically reduces the residual risk, regardless of ethnicity.

Test References:

1. Cusin et al. (2003).  Prevalence of SMN1 deletion and duplication in carrier and normal populations: implication for genetic counseling.  J Med Genet, 40:e39.
2. Dressman et al. (2007).  X-linked infantile spinal muscular atrophy: clinical definition and molecular mapping.  Genet Med, 9(1):52-60.
3. Guenther er al. (2007).  Clinical and mutational profile in spinal muscular atrophy with respiratory distress (SMARD): defining novel phenotypes through hierarchical cluster analysis.  Hum Mutat, 28(8):808-815.
4. Hendrickson et al. (2009).  Differences in SMN1 allele frequencies among ethnic groups within North America.  J Med Genet, 46(9): 641-644.
5. Iannaccone et al (2004).  Spinal muscular atrophy.  Curr Neurol Neurosci Rep, 4(1):74-80.
6. Kaindl et al. (2008).  Spinal muscular atrophy with respiratory distress type 1 (SMARD1). J Child Neurol, 3(2):199-204.
7. Kolb et al. (2007).  Molecular functions of the SMN complex.  J Child Neurol, 22(8):990-994.
8. Lefebvre et al. (1995).  Identification and Characterization of a Spinal Muscular Atrophy-Determining Gene.  Cell, 80:155-165.
9. Lunn and Wang (2008).  Spinal Muscular Atrophy.  Lancet, 371: 2120:2133.
10. Mailman et al. (2002).  Molecular analysis of spinal muscular atrophy and modification of the phenotype by SMN2.  Genet Med, 4(1):20-26.
11. Marques et al. (2006).  Expanding the phenotypes of the Pro56Ser VAPB mutation: proximal SMA with dysautonomia.  Muscle Nerve, 34(6):731-739.
12. Monani (2005).  Spinal muscular atrophy: a deficiency in a ubiquitous protein; a motor neuron-specific disease.  Neuron, 48(6):885-896.
13. Nishimura et al. (2004).  A mutation in the vesicle-trafficking protein VAPB causes late-onset spinal muscular atrophy and amyotrophic lateral sclerosis.  Am J Hum Genet, 75(5):822-831.
14. Ogino and Wilson (2002).  Genetic testing and risk assessment for spinal muscular atrophy (SMA).  Hum Genet, 111(6):477-500.
15. Ogino and Wilson (2004).  Spinal muscular atrophy: molecular genetics and diagnostics. Expert Rev Mol Diagn, 4(1): 15-29.
16. Prior et al. (2004).  Homozygous SMN1 deletions in unaffected family members and modification of the phenotype by SMN2.  Am J Med Genet A, 130(3):307-310.
17. Prior (2007).  Spinal muscular atrophy diagnostics.  J Child Neurol, 22(8):952-956.
18. Prior  (2008).  Carrier screening for spinal muscular atrophy.  Genet Med, 10:840-842.
19. Ramser et al. (2008).  Rare missense and synonymous variants in UBE1 are associated with X-linked infantile spinal muscular atrophy.  Am J Hum Genet, 82(1):188-193.
20. Smith et al. (2007).  Population screening and cascade testing for carriers of SMA.  Eur J Hum Genet, 15: 759-766.
21. Swoboda et al. (2005).  Natural History of Denervation in SMA: Relation to Age, SMN2 Copy Number, and Function.  Ann Neurology, 57(5) 704-712.
22. Sumner (2007).  Molecular mechanisms of spinal muscular atrophy.  J Child Neurol, (8):979-989.
23. Wirth et al (2006).  Mildly affected patients with spinal muscular atrophy are partially protected by an increased SMN2 copy number.  Hum Genet, 119(4):422-428.