BACs-on-Beads Assay for the Prenatal Diagnosis of Microdeletion and Microduplication Syndromes

To evaluate the clinical value of BACs-on-Beads (BoBs) assay in detection of microdeletion and microduplication syndromes. A total of 6,814 cases of amniotic fluid cells collected from January 2015 to July 2020 in our hospital were analyzed by chromosomal karyotyping and BoBs assay. Fluorescence in situ hybridization (FISH) or chromosomal microarray analysis (CMA) provided further validation for the cases of microdeletion and microduplication. Thirty microdeletion and microduplication syndromes were identified by BoBs with an incidence of ~1/227, including 22q11.2 microduplication (0.044%, 3/6814), DiGeorge I syndrome (0.044%, 3/6814), 17p11.2 microduplication (0.015%, 1/6814), Smith–Magenis syndrome (0.015%, 1/6814), 17p11.2p11.3 microduplication (0.015%, 1/6814), Williams–Beuren syndrome (0.088%, 6/6814), 7q11.2 microduplication (0.029%, 2/6814), DiGeorge II syndrome (0.015%, 1/6814), 18p11.32p11.21 microduplication (0.015%, 1/6814), Wolf–Hirschhorn syndrome (0.029%, 2/6814), 4p16.3 microduplication (0.015%, 1/6814), Langer–Giedion syndrome (0.015%, 1/6814), Miller–Dieker syndrome (0.015%, 1/6814), Cri du Chat syndrome (0.015%, 1/6814), Xp22.31 microdeletion (0.059%, 4/6814), Prader–Willi syndrome (0.015%, 1/6814). High concordance was obtained between BoBs and FISH or CMA. However, only four cases were detected by chromosomal karyotyping. BoBs assay can rapidly detect microdeletion and microduplication syndromes, which compensates the shortcomings of conventional chromosomal karyotyping and greatly improves the efficiency and accuracy of prenatal diagnosis.