Referral patterns for microarray testing in prenatal diagnosis.

Objective: To understand the prenatal referral patterns from the United States, Canada, and Israel for two whole-genome microarray platforms, each with a different resolution.

Method: Physicians selected one of the two array designs to be performed on 1483 prenatal specimens for a 1-year period. We retrospectively examined detection rates, indications for study, and physician array selection.

Results: The lower resolution array (55 K) showed an ~32% decrease in the detection of results of unclear clinical significance while retaining the ability to detect all but one significant abnormality identified by the higher resolution array (135 K). A majority of samples were referred for abnormal ultrasound findings. Whereas the United States and Canada utilized the higher resolution array more often for this indication, Israel preferred the 55 K array. Referral patterns for parental anxiety were similar for the United States and Israel, with most cases being tested on the 55 K array. Few cases were referred for advanced maternal age or family history of a genetic condition from either Canada or Israel.

Conclusion: Referral patterns varied between the countries and between indications for study. Understanding these differences will provide laboratories the critical information needed to develop array designs to meet the medical needs and patient desires for prenatal testing.