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Expanded carrier screening offers insights into infant health, not complete picture

NASHVILLE, Tenn. — Though expanded carrier screening can predict likely instances of infant hospitalization or infant mortality before a child is conceived, there is not a complete understanding among the medical and patient communities about what the role of this screening should be, according to a discussion here at the American College of Obstetricians and Gynecologists Annual Clinical and Scientific Meeting.

Data published in Molecular Genetics & Genomic Medicine indicate that approximately 0.2 percent of couples carry matching genes that could lead to a genetic disorder in their offspring, Lorraine Dugoff, MD, chief of the division of reproductive genetics at Penn Medicine in Philadelphia, told attendees.

“Expanded carrier screening allows you to be pan-ethnic, non-selective and you are screening simultaneously for a far larger number of conditions than you ever could with traditional carrier screening,” she said, launching a primer on expanded carrier screening’s benefits and limitations.

“The expanded screening, if it results in a prenatal diagnosis, could lead to benefits such as improved perinatal outcome, immediate care of the neonate and prenatal education of parents regarding special needs,” she said.

 

A speaker here at the American College of Obstetrics and Gynecologists Annual Clinical and Scientific Meeting.said clinicians should advise couples to be completely certain about paternity, otherwise the screening is almost certainly useless.

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Dugoff also said the extended option provides screening for conditions for which carrier screening of the general population is not recommended (such as Factor V Leiden, Fragile X, hemochromatosis) and rare conditions with unknown detection rates and carrier frequencies.

She added that expanded carrier screening may not include previously identified pathogenic and family-specific variants recognized via commercially available tests as well as conditions that can lead to cognitive disability. In addition, for some couples, the screening’s cost can be prohibitive and the screening itself can cause anxiety and stigmatization.

Dugoff added that the ACOG, Society for Maternal-Fetal Medicine, American College of Medical Genetics and Genomics, National Society for Genetic Counselors and Perinatal Quality Foundation collaborated several years ago to publish expanded carrier screening guidelines.

These recommendations, which were published in Obstetrics and Gynecology, provide insight into other benefits and limitations of the procedure, as well as information clinicians should share with couples considering this option:

• “All individuals, regardless of race or ethnicity, are offered screening for the same set of conditions.”
• “[Screening] panels can include more than 100 genetic conditions, most of which are rare. Before testing, it is not practical or necessary to fully explain all of the clinical and test characteristics of each condition.”
• “Pretest education and consent should broadly describe the types of conditions being screened for and their common features as well as the limitations of screening.
• "Educating patients before testing may be done verbally or by using other informational approaches such as pamphlets, videos, or online resources.”
• “The majority of conditions on current expanded panels are autosomal-recessive.”
• “[Screening] panels include most of the conditions recommended in current guidelines.”

However, Dugoff noted these guidelines should not be seen as the final word on expanded carrier screening.

“The bottom line is, these societies said they do not want their guidelines to replace current screening guidelines from individual organizations in this area,” she said.

Dugoff also said clinicians should advise couples to be completely certain about paternity, otherwise the screening is almost certainly useless.

She added that couples need to understand that even if the screening comes back negative for certain condition, the risk for that condition is not completely negated. –by Janel Miller

References:

Dugoff L. “Non-invasive prenatal screening (NIPS) and carrier screening: Pearls and pitfalls.” Presented at: American College of Obstetricians and Gynecologists Annual Clinical and Scientific Meeting; May 3-6, 2019; Nashville.

Also: Edwards KG, et al. Obstet Gynecol. 2015 Mar;125(3):653-62. doi: 10.1097/AOG.0000000000000666.

Disclosures: Dugoff reports receiving financial/material support and research funding from Progenity. Please see the study for those authors’ relevant disclosures.