255: First trimester serum analytes as predictors of pathologic copy number variants (CNV) on chromosomal microarray analysis (CMA)

To determine whether abnormal first trimester serum analytes (low PAPP-A and/or beta-hCG) are associated with pathologic copy number variants (CNV) on chromosomal microarray (CMA). This retrospective cohort included all CMA studies (n = 2880) that were performed via chorionic villus sampling (CVS) or amniocentesis at a single institution in a single laboratory from 2011 to 2017. We excluded cases in which an abnormal karyotype was detected, as well as multiple gestations or those who had no prior nuchal translucency screening. The prevalence of abnormal serum analytes was compared between patients with pathologic CNVs (abnormal CMA, VOUS likely abnormal, and mosaics) i.e. study group (n = 56) and those with normal CMAs i.e. controls (n = 884). Odds ratios were calculated and statistical significance was determined as p < 0.05. Low serum free beta-hCG (<= 0.45 MoM) was associated with an increased risk for pathologic CNV (OR 3.53, p < 0.01), as well as for abnormal CNV (OR 4.7, p < 0.01) (Table 1). The association of pathologic CNV with low serum PAPP-A (<= 0.4 MoM) was not statistically significant (OR 1.26, p = 0.6) (Table 1). Low first trimester serum beta-hCG is associated with an increased risk of pathologic, as well as, abnormal CNVs on CMA testing. This strong association should be taken into consideration when counseling patients regarding abnormal serum beta-hCG levels.