Chromosomal microarray analysis for pregnancies with abnormal maternal serum screening who undergo invasive prenatal...

Area of Science:

• Prenatal Diagnosis
• Genetics
• Obstetrics

Background:

• Chromosomal microarray analysis (CMA) is increasingly used for pregnancies with ultrasound anomalies.
• Its utility in pregnancies solely based on abnormal maternal serum screening (AMSS) requires further evaluation.
• Traditional karyotyping is the standard for prenatal diagnosis.

Purpose of the Study:

• To evaluate the diagnostic value of CMA compared to karyotyping in pregnancies with AMSS.
• To assess the incremental yield of CMA in pregnancies with AMSS, with or without ultrasound anomalies.
• To determine the frequency of variants of unknown significance (VUS) with CMA in these pregnancies.

Main Methods:

• Retrospective analysis of 3973 pregnancies referred for invasive prenatal testing due to AMSS (April 2016-May 2020).
• Comparison of CMA results with traditional karyotyping.
• Categorization of fetuses into AMSS only (Group A) and AMSS with ultrasound anomalies (Group B).
• CMA was performed on 713 prenatal samples.

Main Results:

• The incremental yield of clinically significant findings in pregnancies with high-risk AMSS results was comparable to those with ultrasound soft markers but lower than those with structural anomalies.
• No significant difference in the total frequencies of variants of unknown significance (VUS) was observed between Group A and Group B.
• The uptake of CMA testing increased over the study period in both groups.

Conclusions:

• CMA is a valuable tool for prenatal diagnosis in pregnancies with AMSS, particularly with high-risk results.
• CMA should be considered for pregnant women undergoing invasive prenatal testing due to AMSS, irrespective of concurrent ultrasound findings.
• CMA provides comparable diagnostic yield to karyotyping in specific high-risk prenatal screening scenarios.