What parents should know before genetic testing for SMA

Spinal muscular atrophy (SMA) is a rare genetic condition that can cause muscle weakness and issues with mobility, breathing, and swallowing. When planning a family, you may have questions about the chances of passing the condition on to your children and about genetic testing options.

These are natural concerns, but learning more about SMA in babies, genetic testing for SMA, and SMA carrier testing can help ease some of the uncertainty you may experience.

How genetic testing can help spot SMA early

Genetic testing for SMA can help to diagnose a child with the condition before symptoms appear. In the past, parents of children with SMA didn’t know that their youngster had the condition until they showed the early signs of SMA, such as issues with muscle control and difficulty holding up the head. By that time, the child could have experienced irreversible muscle loss that would not be addressed by treatment.

Newborn screening for SMA can now detect disease-related genetic changes soon after birth, allowing doctors to begin treatment promptly, sometimes before SMA symptoms become evident in infants. This can help children reach developmental milestones, such as holding their heads up, sitting without support, or walking.

SMA carrier testing can also help determine whether you or your partner may carry the genetic mutation for SMA before you start a family. This information can assist you with SMA family planning and allow your doctor to discuss appropriate reproductive options and prenatal testing.

When should parents think about getting tested?

Being an SMA carrier is more common than many people think: about 1 in 50 people carry a mutated copy of the SMN1 gene and a healthy copy. Because most carriers have no symptoms, several tests may be considered before, during, and after pregnancy to better understand your SMA risk.

Before pregnancy, you can consider carrier screening, especially if you or your partner has a family history of neuromuscular disorders.
During pregnancy, prenatal testing for SMA can be done if you, your partner, or both are carriers. Other tests can examine if the fetus has inherited the condition.
After birth, newborn screening and other tests can be performed to establish an SMA diagnosis.

What test results can (and can’t) tell you about SMA

While genetic testing can provide you with helpful information, it is not without limitations.

SMA carrier testing can help determine if you are a carrier of a mutation in the SMN1 gene. If both you and your partner are carriers, you have a 25% chance of having a child with SMA.

However, genetic testing can only detect 95% of all carriers in the general population. And when it does confirm that someone has SMA or is a carrier, it cannot anticipate how severe the condition will be or when symptoms may appear.

This is part of the reason why it is important to consult a genetic counselor, who can provide more information on how to interpret test results.

Genetic counseling and SMA testing

SMA genetic counseling can help you understand your family history, genetic testing options, and potential outcomes for your family.

A genetic counselor can help you by:

estimating the likelihood of passing on SMA to offspring
interpreting test results
discussing the reliability and limitations of genetic testing

They can also outline reproductive options for SMA carriers, which may include:

in vitro fertilization and SMA testing
using donor eggs or sperm
opting for adoption

The counselor can also help you manage the emotional and psychological aspects of being a carrier and connect you with resources to help you better understand SMA, make informed choices, and find community support.

Finding a specialist for testing and support resources

If you are considering SMA genetic testing, finding the right specialists can make a meaningful difference.

You can start by talking to your primary care provider or OB-GYN, who can refer you to a genetic counselor or another expert specializing in SMA.

SMA organizations, such as Cure SMA and the Muscular Dystrophy Association, can provide additional information about genetic testing and carrier screening for SMA. Your doctor may also recommend local SMA organizations that can help connect you with SMA families.

Family planning with SMA can be challenging, but having the right information and expert support can help you make the best decisions for your family’s future.

SMA News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.