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Expanded carrier screening: A review of growing consensus

5 questions with the lead author, Gabriel Lazarin, MS, CGC.

Expanded carrier screening screenshot

5 questions with the lead author

Shivani Nazareth, Director of Women’s Health at Counsyl, sits down with lead author and VP of Clinical Specialists at Counsyl, Gabriel Lazarin, to discuss his recent publication in Seminars of Perinatology: Expanded carrier screening: A review of early implementation and literature”¹

Shivani: What do you think led to ACOG, NSGC and other key medical societies to put forth a joint statement on expanded carrier screening?

Gabriel: The realization that expanded carrier screening is here to stay, and that the medical community is in need of guidance from experts in the field. When we first introduced expanded carrier screening in 2010, we were met with a ton of resistance from genetic counselors and physicians.

Now five years later, the authors of the joint statement acknowledge the limitations of relying on ethnicity/ancestry to determine what diseases we offer to patients. Counsyl has played a big part in helping our colleagues offer expanded carrier screening in a clinically responsible way.

I think the joint statement is a testimony to the hard work that many people put into making expanded carrier screening a part of routine care.

Shivani: In your recent publication, you review the broad implementation of expanded carrier screening over the past few years. What did you find most interesting?

Gabriel: Widespread implementation has allowed the clinical community to more objectively estimate carrier frequencies and associated risks. Personally, I found those numbers to be intriguing.

As an example, data from a large multi-ethnic population revealed that the collective incidence of the “rare diseases” exceeded that of open neural tube defects or trisomy 21 in a 20-y old woman. This is a concept that geneticists have long inferred, but now concrete data allows for a more productive discussion of why we offer screening to patients.

Shivani: Can you talk about how we as genetic counselors can start to address pre-test counseling for so many conditions?

Gabriel: Sure, and the review article provides guidance on this as well.

As we screen patients for more conditions, whether it’s carrier screening for recessive diseases or hereditary cancer screening for a large number of genes, it’s fair to say that our current model of pre-test counseling is not sustainable.

Elias and Annas² described the elements of generic informed consent in their New England Journal piece, and we adapted their model for expanded carrier screening. In my paper, I review the ideal elements for pre-test consent, including an overview of disease categories, risk estimates, screening limitations, and next steps for high-risk couples.

Clinicians already do this for ultrasounds and other routine prenatal tests. We’re obviously not going over every possible birth defect that can be picked up on an ultrasound, but we give patients an overview of what to expect.

Shivani: In your paper, you note that there is widespread acceptance of expanded carrier screening, but only 15% of ACOG Fellows are routinely offering it to all of their patients. Why do think this is the case?

Gabriel: From my conversations with genetic counselors and doctors across the country, I suspect there is still some discomfort around how to counsel for a broad array of conditions. I’m hopeful that uptake of expanded carrier screening will grow as we start to agree upon best practices.

Shivani: What would constitute “success” in your eyes, when it comes to implementation?

Gabriel: That’s easy: everyone is offered expanded carrier screening before conception.

We still hear too many stories of couples who have lost children to rare diseases and had no idea screening was available. I think we have an obligation to these parents to change the way screening is practiced, and I will continue to beat this drum until we get there.


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Learn more about the Counsyl Family Prep Screen here.


¹Lazarin GA, Haque IS. Expanded carrier screening: A review of early implementation and literature. Semin Perinatol. 2015
²Elias S, Annas GJ. Generic consent for genetic screening. N Engl J Med 1994;330:1611-1613

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