Finding Middle Ground in Constructing a Clinically Useful Expanded Carrier Screening Panel.

Expanded carrier screening for autosomal-recessive conditions effectively identifies more carrier couples than traditional guideline-based carrier screening. However, clinically available expanded carrier screening panels include numerous conditions, some of which have questionable clinical utility as a result of very low carrier frequency, low or unknown testing sensitivity, and mild or incompletely penetrant phenotypes. Using the 2013 American College of Medical Genetics and Genomics Position Statement on Prenatal and Preconception Expanded Carrier Screening and the 2017 American College of Obstetricians and Gynecologists' Committee Opinion on Carrier Screening in the Age of Genomic Medicine as guidance, we propose specific criteria for the development of expanded carrier screening panels that will maximize clinical utility and minimize patient stress, unnecessary cost of follow-up testing, and clinician time spent facilitating and performing follow-up counseling and testing. We identified 96 conditions that meet our proposed criteria, far more than current guidelines recommend. On the other hand, a considerable percentage (73%) of conditions on current expanded carrier screen panels does not meet our proposed criteria. The purpose of this commentary is to acknowledge the benefits of expanded panels, but to also recognize that in their current state, we are putting patients at risk for undue stress and spending excessive time and money on follow-up testing for remarkably rare or mild conditions and conditions with low screening performance. We encourage laboratories and clinicians to work together to create the most clinically useful screening panels for patients desiring reproductive risk information.