725: A retrospective study of BACs-on-Beads (BoBs) technology for identification of chromosome abnormalities compared with QF-PCR and karyotyping in prenatal diagnosis

The Comprehensive Comparison of Bacterial Artificial Chromosomes (BACs)-on-Beads Assay and Copy Number Variation Sequencing in Prenatal Diagnosis of Southern Chinese Women

Bacterial artificial chromosomes (BACs)-on-Beads (BoBs) assay and copy number variation sequencing (CNV-seq) are two frequently used methods in today's prenatal diagnosis. Several studies were conducted to investigate the performance of each approach, but they were never compared side by side. In this article, a comprehensive comparison of BoBs and CNV-seq was conducted using 1876 amniotic fluid and umbilical cord blood samples collected from Fujian Maternity and Child Health Hospital between 2015 and 2019. Karyotyping was used as the gold standard for chromosome structure variation, and chromosomal microarray analysis was performed to validate inconsistent results. Overall, 174 cases of confirmed chromosome anomalies were detected, including 73 chromosomal aneuploidies, 10 mosaics, 30 pathogenic CNVs, and 61 other structural anomalies. BoBs and CNV-seq achieved a 100% concordance in all 55 pathogenic euchromosome aneuploidies, but CNV-seq had a higher detection rate in sex chromosome aneuploidy and mosaic identification. For CNV detection, all of the 20 pathogenic CNVs discovered by the BoBs assay also were identified by CNV-seq and 10 additional pathogenic CNVs were observed by CNV-seq. The results of this study showed that CNV-seq was a reliable and more favorable method in terms of detection rate, costs, and disease range. In combination with karyotyping, CNV-seq could improve the efficiency and accuracy of a prenatal diagnosis to alleviate maternal emotional anxiety and deduce birth defects.

Combined use of bacterial artificial chromosomes-on-beads with karyotype detection improves prenatal diagnosis

Background

This study evaluated the individual and combined diagnostic performance of the bacterial artificial chromosomes (BACs)-on-Beads (BoBs™) assay and conventional karyotyping for the prenatal detection of chromosomal abnormalities in pregnant women who were 35 or more years-old.

Method

The primary outcome was concordance of any numerical, structural, or submicroscopic chromosomal abnormalities between BoBs™ and conventional karyotyping of amniotic fluid specimens from pregnant women at 17 to 22 weeks gestation.

Results

We examined samples from 4852 pregnant women. BoBs™ indicated that 4708 samples were normal (97.03%), and 144 were abnormal (2.97%); conventional karyotyping indicated that 4656 (95.96%) samples were normal and 196 (4.04%) were abnormal. The combined use of both methods indicated that 4633 of 4852 samples were normal (95.49%) and 219 of 4852 samples (4.51%) were abnormal. The kappa coefficient of the combined test was 0.70, indicating substantial consistency between BoBs™ and conventional karyotyping (95% CI = 0.65–0.76, P < 0.001).

Conclusions

Our results indicate that the combined use of BoBs™ and conventional karyotyping detected more fetal abnormalities than either test alone.