Detection rates of abnormalities in over 10,000 amniotic fluid samples at a single laboratory.

BACKGROUND: A growing number of cytogenetic techniques have been used for prenatal diagnosis. This study aimed to demonstrate the usefulness of karyotyping, BACs-on-Beads (BoBs) assay and single nucleotide polymorphism (SNP) array in prenatal diagnosis during the second trimester based on our laboratory experience. METHODS: A total of 10,580 pregnant women with a variety of indications for amniocentesis were enrolled in this retrospective study between January 2015 and December 2020, of whom amniotic fluid samples were analysed in 10,320 women. The main technical indicators of participants in the three different technologies were summarized, and cases of chromosome abnormalities were further evaluated. RESULTS: The overall abnormality detection rate of karyotyping among all the amniotic fluid samples was 15.4%, and trisomy 21 was the most common abnormality (20.9%). The total abnormality detection rate of the BoBs assay was 5.6%, and the diagnosis rate of microdeletion/microduplication syndromes that were not identified by karyotyping was 0.2%. The detection results of the BoBs assay were 100.0% concordant with karyotyping analysis in common aneuploidies. Seventy (87.5%) cases of structural abnormalities were missed by BoBs assay. The total abnormality detection rate of the SNP array was 21.6%. The detection results of common aneuploidies were exactly the same between SNP array and karyotyping. Overall, 60.1% of structural abnormalities were missed by SNP array. The further detection rate of pathogenic significant copy number variations (CNVs) by SNP was 1.4%. CONCLUSIONS: Karyotyping analysis combined with BoBs assay or SNP array for prenatal diagnosis could provide quick and accurate results. Combined use of the technologies, especially with SNP array, improved the diagnostic yield and interpretation of the results, which contributes to genetic counselling. BoBs assay or SNP array could be a useful supplement to karyotyping.

Application of the BACs-on-Beads assay for the prenatal diagnosis of chromosomal abnormalities in Quanzhou, China.

BACKGROUND: An increasing number of techniques have been used for prenatal diagnosis of genetic abnormalities. Our initial objective was to explore the value of the BACs-on-Beads (BoBs) assay for the prenatal diagnosis of aneuploidies and microdeletion/microduplication syndromes in Quanzhou, Southeast China. METHODS: A total of 1409 pregnant women with high-risk factors for chromosomal abnormalities admitted to Quanzhou Women's and Children's Hospital were enrolled in this study. BoBs assays and karyotype analyses were conducted for all subjects. Subsequently, chromosome microarray analysis (CMA) or fluorescence in situ hybridization (FISH) was performed to validate the findings. RESULTS: In this study, karyotype analysis and BoBs assay failed in 4 cases, and 2 cases, respectively. A total of 1403 cases were successfully analyzed, with success rates of 99.72% (1405/1409) and 99.85% (1407/1409) for karyotype analysis and Bobs assay, respectively. BoBs assay rapidly detected chromosomal aneuploidies in line with the karyotyping data. Additionally, 23 cases of microdeletions/microduplications were detected by BoBs assay but missed by karyotyping, including 22q11.2 microdeletions/microduplications, 5p15.32p15.33 microdeletion, Xp22.31 microdeletions/microduplications, Xq27.3 microdeletion, and Yp11.2 and Yq11.22q11.222 microduplication. In comparison with karyotyping, fewer mosaicisms were identified by BoBs assay. A high detection rate of chromosomal abnormalities was observed in the high-risk group during noninvasive prenatal testing (NIPT) (41.72%) and the abnormal ultrasound group (13.43%). CONCLUSIONS: BoBs assay can be used for the rapid and efficient prenatal diagnosis of common aneuploidies and microdeletion/microduplication syndromes. Moreover, the combined use of BoBs assay and karyotyping in prenatal diagnosis may allow for a more effective detection of chromosomal abnormalities.

Prenatal Diagnosis of BACs-on-Beads Assay in 3647 Cases of Amniotic Fluid Cells.

OBJECTIVE: To evaluate the diagnostic accuracy of the BACs-on-Beads (BoBs) assay for the rapid diagnosis of common aneuploidies and microdeletion syndromes. METHODS: BACs-on-Beads and chromosomal karyotyping were used for detecting 3647 cases of amniotic fluid samples with indications for prenatal diagnosis, which were collected from January 2015 to June 2017 in Xijing Hospital. Fluorescence in situ hybridization (FISH) or chromosomal microarray analysis (CMA) provided further validation. RESULTS: The overall abnormality detection rate (BoBs combined with karyotyping) was 7.73% (282/3647). A total of 209 chromosomal aneuploidies, 10 mosaic cases, 11 microdeletion/microduplication syndromes, and 52 structural abnormalities were observed. Both assays were concordant for trisomy 21 (4.22%, 154/3647), trisomy 18 (0.69%, 25/3647), trisomy 13 (0.05%, 2/3647), and sex chromosome aneuploidies (0.77%, 28/3647). Meanwhile, DiGeorge syndrome (0.05%, 2/3647), 22q11.2 microduplication (0.08%, 3/3647), Smith-Magenis syndrome (0.03%, 1/3647), 17p11.2 microduplication (0.03%, 1/3647), Wolf-Hirschhorn syndrome (0.03%, 1/3647), Williams-Beuren syndrome (0.03%, 1/3647), Cri du Chat syndrome (0.03%, 1/3647), and Miller-Dieker syndrome (0.03%, 1/3647) were identified by BoBs assay, thus giving the incidence of the detection of these syndromes of 0.30% (11/3647). CONCLUSION: BACs-on-Beads assay is a reliable test for rapid detection of common aneuploidies and microdeletion syndromes, combining with karyotyping, FISH, and CMA, to improve the efficiency and accuracy of prenatal diagnosis to alleviate maternal emotional anxiety.