Comparing ethnicity-based and expanded carrier screening methods at a single fertility center reveals significant differences in carrier rates and carrier couple rates

Purpose: To evaluate the efficiency of expanded carrier screening (ECS) compared with ethnicity-based screening in identifying carriers. Methods: A total of 4232 infertility patients underwent ECS from a single genetic testing laboratory at our center between June 2013 and July 2015. Self-reported ethnicity was recorded. Carrier rates based on ECS were calculated. In addition, carrier status was determined for two other screening panels: ethnicity-based guidelines or the ECS panel recommended by the American College of Obstetricians and Gynecologists (ACOG) using ECS results. Carrier rate and carrier couple rates were compared in the overall study population and in each self-reported ethnicity. Results: The ECS panel used to screen the patient population identified 1243 carriers (29.4%). For the same population, ethnicitybased screening and the ACOG panel would have identified 359 (8.5%) and 659 carriers (15.6%), respectively, representing statistically significant differences. Differences in identifying carriers across self-reported ethnicities varied. In 15 couples (1.2%), both partners carried pathogenic variants for the same genes, 47% of whom would have been missed had screening been ethnicity-based. Conclusion: We propose that all reproductive-aged women should be offered ECS. Carrier couple rates would likely increase further with expansion of the panel, playing a pivotal role in preventing genetic disease in fertility clinics.