Expanded Carrier Screening is Important for All Who are Pregnant or Considering Pregnancy
By Dr. James Goldberg, M.D.
“Is my baby healthy?” was one of the most asked questions I received when I was in clinical practice. While there is no one test you can perform to answer that, there are screening tests available that can give you insight into the health of your baby – one example is carrier screening.
Carrier screening can help determine whether you carry inherited health conditions that you might pass on to your child. Many people are carriers and simply don’t know it. These serious conditions may reduce lifespan, result in intellectual disability, or require prompt treatment following birth. Knowing this information either before you get pregnant or early in pregnancy can allow you to develop a personalized care plan with your provider.
Sometimes, the chance of being a carrier for a specific condition can be higher in certain ethnicities. One example is that the carrier frequency in the Ashkenazi Jewish population for Tay-Sachs disease is higher than in non-Ashkenazi Jewish individuals. For this reason, when medical guidelines for carrier screening were designed, screening for Tay-Sachs disease was recommended to be limited to those who reported Ashkenazi Jewish descent or had a family history of Tay-Sachs disease. Even today, medical guidelines use patient self-reported ethnicity as a criterion for which conditions a patient is screened for.
However, we know it’s possible for anyone to be a carrier for any condition, regardless of their race or self-reported ethnicity. Additionally, a large proportion of people cannot accurately pinpoint the ethnicities of their ancestors, and many people have mixed ethnicities. In the past decade, carrier screening technology has evolved to allow for screening of many serious conditions at the same time no matter a person’s ethnicity – it’s called expanded carrier screening (ECS). Offering ECS to all patients who are pregnant or considering pregnancy, regardless of race or self-reported ethnicity, better identifies carriers as compared to the ethnicity-based screening guidelines.
How do we know this? Researchers at Myriad Genetics recently conducted a carrier screening study of over 93,000 people in an ethnically diverse population. They compared the results from ECS to those from ethnicity-based screening, and they also compared the actual genetic ancestry of the population to their self-reported ethnicity.
Results showed that only 23 percent of carriers would have been identified through ethnicity-based screening protocols. Further, for almost half of the conditions (seven of 16) included in guidelines, most carriers were not from ethnic groups previously thought to be at higher risk of being a carrier for these genetic disorders.
Missing more than 75 percent of carriers is unacceptable. I know we can do better. Expanded carrier screening allows us to screen every person for many conditions, regardless of race or ethnicity. It is my aspiration that the guidelines be revised to reflect what we now know about these conditions and how best to detect carriers.
If you are pregnant or considering trying, I urge you to speak your healthcare provider about expanded carrier screening.