The diagnostic accuracy of maternal serum alpha-fetoprotein variants (AFP-L2 and AFP-L3) in predicting fetal open neural tube defects and abdominal wall defects

Abstract

Introduction: To evaluate a risk model of the maternal serum α-fetoprotein variants L2 and L3 (AFP-L2 and AFP-L3) for predicting fetal open neural tube defects (ONTD) and abdominal wall defects (AWD).

Methods: Subjects were divided into the ONTD group (21), the AWD group (16) and the control group (38). Comparative analysis was performed using a risk model, receiver operating characteristic (ROC) curves and area under the curve (AUC) were used for screening performance of AFP-L2 and AFP-L3.

Results: AFP-L2 and AFP-L3 concentrations in the ONTD group and the AWD group were both significantly higher than those in the control group (P < 0.001). The AUC for screening ONTD or AWD using AFP-L2 was 0.830 [95% confidence interval (CI):0.734-0.926, P < 0.001], while using AFP-L3 was 0.886 (95% CI: 0.809-0.963, P < 0.001). ROC curves indicated that the optimal threshold values for ONTD or AWD by AFP-L2 and AFP-L3 were 1.467 multiple of the median (MoM) and 1.944 MoM. The corresponding sensitivity, specificity and Youden index for AFP-L2 and AFP-L3 were 0.703, 0.947, 0.650 and 0.730, 0.974, 0.703, respectively.

Conclusion: AFP-L2 and AFP-L3 are favorable biomarkers for screening ONTD and AWD fetuses, and the risk model using AFP-L2 and AFP-L3 is of superior sensitivity and specificity.

Keywords: Abdominal wall defects; Casecontrolled study; Fetoprotein variant AFP-L2/AFP-L3; Open neural tube abnormalities; Risk modelling; Second Trimester.