Carrier test shows what genes parents may pass to kids

Genetic counselors can screen couples for 100+ hereditary conditions while family planning

A little boy is curious about his mother's growing belly as he sits on his father's lap.

The amount of information in our genetic code is astounding.

Our genes affect everything — from physical features such as eye and hair color to whether we may develop certain health concerns such as high blood pressure or even cancer. While a great deal of genetic testing is performed to evaluate personal health risks, individuals thinking about becoming parents have the option to screen for various genetic conditions that may affect their future children.

This type of testing is called carrier screening. Carrier screening is a blood test that checks to see if parents are carriers for certain genetic conditions. For most of the conditions, being a carrier is unlikely to cause a concern for their own health.

Find a genetic counselor: Carrier screening and more at Sanford Health

When someone is identified as a carrier, that means they have one copy of gene that is not working. If both parents carry the same genetic condition, there is a chance for each of their future children to be affected.

Why choose carrier testing

For example, if both parents are carriers for cystic fibrosis, a condition that primarily affects the lungs and digestive system, there is a chance each parent will each pass down their non-working gene and have a child affected with the condition.

“We are all carriers for a handful of genetic conditions,” said RaeAnn Coughlin, a certified genetic counselor with Sanford Health. “When I first meet with couples in clinic, they often wonder ‘why would I need carrier screening when there is nothing in my family history?’ The decision to pursue carrier screening often has little to do with the family history. When a baby is born with a genetic disease, the parents often look around and say ‘who is affected in our family?’ or ‘where did this come from?’ and most of the time the answer is no one.

“That is because these things happen due to the combination of both parents’ genetic information. Carriers do not typically have symptoms, so more often than not, the parents didn’t know they were carriers. None of us are genetically perfect. While greater than 99% of our genes are the same, we all harbor certain genes that do not function properly,” Coughlin explained.

What you can learn from carrier testing

While most people may be aware of conditions that run in their family such as diabetes or heart disease, carrier screening can provide information about possible health risks that may not be apparent in the family.

“Most conditions we offer screening for are considered ‘recessive’ disorders,” Coughlin said. “This means that they are not usually apparent when mapping out the family history and most parents would not have any idea what they carry without doing testing. These conditions happen when two people get together, and just by chance, happen to carry the same genetic condition.”

Carrier screening often evaluates for over 100 conditions.

For some individuals, knowledge can be power. Being aware of carrier status may influence couples’ reproductive planning and decision-making. For others, this type of information can seem overwhelming or cause anxiety. One of the first things a genetic counselor will do when talking about carrier screening is to ask what some of these conditions or knowledge of the results may mean to them.

Timing your screening

For example, is the couple concerned about a certain genetic condition? Or, if the couple were to find out they are carriers for the same condition, would their family planning or pregnancy management change?

“Carrier screening is a personal choice,” Coughlin said. “While no test can guarantee a healthy child, carrier screening can aid couples in making decisions for their family. It is recommended that all couples are offered carrier screening prior to conception or during pregnancy so they can make informed decisions that best suit their family goals.”

Coughlin said carrier screening can be completed in multiple stages. A couple can have carrier screening completed at the same time and receive their results together. Alternatively, one person can be screened first. They can then review the results, decide whether the information is helpful or concerning, and decide whether the other partner should be screened.

“Although being a carrier of one or more conditions is common, it is uncommon for both individuals to carry the same condition,” Coughlin said. “Most couples are provided with reassuring news that there is a low chance for the conditions screened.

“For individuals that are interested in learning more about screening, they can ask their provider if they can speak with one of the Sanford genetic counselors. We can help you decide what testing option is best for your family and will help make sense of the results.”

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Posted In Children's, Genetics, Health Information, Pregnancy, Women's