This month, we are striving to bring awareness to Spinal Muscular Atrophy (SMA), a serious inherited condition caused by changes in the SMN1 gene, which controls motor neurons in the spinal cord and brainstem. Symptoms can begin prior to six months of age, in childhood, or, more rarely, in adulthood. In the most common form of the disease, lifespan is often less than two years of age.
Did You Know?
- 1 in 50 Americans is a carrier for SMA
- SMA is the number one genetic cause of death for children under the age of two
- SMA affects families of all ethnicities
- Most people who are carriers have no family history of the disease
How is Spinal Muscular Atrophy (SMA) Inherited?
SMA is caused by a gene mutation in the SMN1 gene. In most cases, both parents must be carriers of the condition in order to have a child with SMA. Carriers are not themselves affected by the disease, but have a chance of having a child with the disease.
| Spinal Muscular Atrophy | |
| Inheritance | If both parents are carriers, there is a 25% chance for each child to be affected. |
| Carrier Frequency | SMA has an ~1 in 54 carrier frequency Affects all racial and ethnic groups, and as with most genetic diseases, there is some ethnic variability in carrier frequencies SMA carrier risk in people with no family history of SMA Caucasian 1 in 35 Ashkenazi Jewish 1 in 41 Asian 1 in 53 African American 1 in 66 Hispanic 1 in 117 |
| Incidence | Has an estimated incidence of 1 in 11,000 births. |
Carrier frequencies/detection rates are calculated based on analysis of allele frequencies among >72,000 individuals.1
Who Should Get Tested?
Carrier screening for SMA should be offered to all women who are considering pregnancy or are currently pregnant and have had appropriate counseling about the possible range of severity, carrier frequency, and detection rate. The American College of Obstetrics and Gynecology (ACOG) recommends that carrier screening for SMA be offered to all women who are considering pregnancy or are already pregnant.2
Carrier Screening at GenPath Women’s Health
At GenPath Women’s Health and BioReference Laboratories, we believe carrier screening for serious conditions like SMA is an essential part of preconception or prenatal care. Carrier screening allows you to plan and prepare by learning the risks for having a child with SMA.
Click here for more information about GenPath Women’s Health and test offerings that may be right for you.
Sources:
- Hendrickson BC, Donohoe C, Akmaev VR, et al. Differences in SMN1 allele frequencies among ethnic groups within North America. J Med Genet2009; 46:641–644.
- https://www.acog.org/womens-health/faqs/carrier-screening-for-spinal-muscular-atrophy
