[Application of Array-based Comparative Genomic Hybridization in Diagnostic Assessment of Abnormal Prenatal Serological Screening Results of Down's Syndrome].

OBJECTIVE: To explore the application of array-based comparative genomic hybridization (a-CGH) technology in the prenatal diagnostic assessment of abnormal serological prenatal screening results of Down's syndrome (DS). METHODS: A total of 3 578 amniotic fluid samples from pregnant women who underwent amniocentesis for prenatal diagnosis solely due to abnormal serological prenatal screening results were selected. The samples were categorized into 3 groups, 2 624 in the high-risk group, 662 in the borderline-risk group, and 292 in the abnormal multiple of median (MoM) group. a-CGH was performed on the Agilent CGX ™ (8×60K) platform and the data were analyzed by the Genoglyphix ® software. RESULTS: The overall detection rate of chromosomal abnormalities was 3.38% (121/3 578). Among the chromosomal abnormalities, 49.59% (60/121) was aneuploidies, 42.15% (51/121) was pathogenic copy number variants (pCNVs), and 8.26% (10/121) was likely pathogenic CNVs (lpCNVs). The detection rate of copy number variant of uncertain significance (VUS) was 1.03% (37/3 578). In the high-risk, the borderline-risk and the abnormal MoM groups, the detection rate of chromosomal abnormalities was 3.54% (93/2 624), 2.87% (19/662) and 3.08% (9/292), respectively; the detection rate of p/lp CNVs was 1.64% (43/2 624), 1.81% (12/662) and 2.05% (6/292), respectively; the detection rate of trisomy 21 and trisomy 18 was 1.37% (36/2 624), 0.76% (5/662) and 0.34% (1/292) in the three groups, respectively. There were no significant differences in all the detection rate among these groups ( P>0.05). One sample with X(51)/XYY(49) confirmed by fluorescence in situ hybridization (FISH) was misdiagnosed by a-CGH. CONCLUSION: Prenatal diagnosis with a-CGH is of great significance for reducing birth defects in pregnancies with abnormal serological prenatal screening results of DS. It can also be used to detect CNVs of microdeletion/microduplication syndromes.

[Application of Array-based Comparative Genomic Hybridization in the Prenatal Diagnosis of Fetal Chromosomal Aberration in Gravidas with Advanced Age].

OBJECTIVE: To evaluate the clinical application of array-based comparative genomic hybridization (a-CGH) in the prenatal diagnosis of fetal chromosomal aberrations in gravidas with advanced maternal age (AMA). METHODS: A total of 3 677 amniotic fluid samples from pregnant women who underwent amniocentesis for prenatal diagnosis solely due to AMA were selected. Array-CGH was performed on the Agilent CGX TM (8X60K) platform and the data were analyzed by the Genoglyphix software. RESULTS: The overall detection rate of chromosomal aberration was 2.04% (75/3677), with 53.33% (40/75) being aneuploidies, including 22 cases of trisomy-21, 5 cases of trisomy-18, 8 cases with XXY, 3 cases of XYY and 2 cases of mosaic monosomy X, 32.00% (24/75) being pathogenic copy number variations (pCNVs), including 19 cases of microdeletion and 5 cases of microduplication, with the fragment size ranging from 323 kb to 26 780 kb, and 14.67% (11/75) being likely pathogenic CNVs (lpCNVs), including 7 cases of microdeletion and 7 cases of microduplication, with the fragment size ranging from 358 kb to 16 873 kb. Besides, the detection rate of CNVs of unknown clinical significance (VUS) was 0.84% (31/3 677). The detection rate of aneuploidies increased significantly with increased maternal age ( P<0.05). However, there were no significant differences in the detection rate of p/lpCNVs among different maternal age groups ( P>0.05). CONCLUSION: Our findings suggest that, compared with traditional karyotype analysis, a-CGH not only detects aneuploidies, but also detect pathogenic CNVs, including microdeletion/microduplication syndromes. The detection rate of fetal aneuploidies was closely correlated to maternal age. However, no correlation was found between the detection rate of p/lpCNVs and maternal age.

A chromosomal microarray analysis-based laboratory algorithm for the detection of genetic etiology of early pregnancy loss.

Background: Chromosomal abnormalities are a major cause of early pregnancy loss. However, models synthesizing existing genetic technologies to improve pregnancy outcomes are lacking. We aim to provide an integrated laboratory algorithm for the genetic etiology of couples who experienced pregnancy loss. Methods: Over a 6-year period, 3,634 products of conception (POCs) following early pregnancy loss were collected. The clinical outcomes from a laboratory algorithm based on single nucleotide polymorphism (SNP) array, fluorescence in situ hybridization (FISH), and parental chromosomal karyotyping assays were comprehensively evaluated. Results: In total, 3,445 of 3,634 (94.8%) POCs had no maternal-cell contamination. Of those POCs, the detection rate of abnormal results was 65.2% (2,247/3,445), of which 91.2% (2,050/2,247) had numerical chromosomal abnormalities, 2.7% (60/2,247) had copy-number variations (CNVs) ≥10 Mb, 2.7% (61/2,247) had CNVs of terminal deletion and duplication, 2.8% (62/2,247) had CNVs <10 Mb, and 0.6% (14/2,247) had uniparental disomy. Furthermore, FISH confirmed 7 of the 60 POCs with mosaic aneuploids below 30% based on the SNP array results as tetraploid. Of the 52 POCs with CNVs of terminal deletion and duplication, 29 couples had balanced rearrangements based on chromosomal karyotyping. Conclusion: The integrated SNP array-based algorithm combined with optional FISH and parental chromosomal karyotyping is an effective laboratory testing strategy, providing a comprehensive and reliable genetic investigation for the etiology of miscarriage, regardless of the number of miscarriages and the method of conception.

Clinical experience of noninvasive prenatal testing for rare chromosome abnormalities in singleton pregnancies.

Objectives: The study aimed to investigate the clinical use of noninvasive prenatal testing (NIPT) for common fetal aneuploidies as a prenatal screening tool for the detection of rare chromosomal abnormalities (RCAs). Methods: Gravidas with positive NIPT results for RCAs who subsequently underwent amniocentesis for a single nucleotide polymorphism array (SNP array) were recruited. The degrees of concordance between the NIPT and SNP array were classified into full concordance, partial concordance, and discordance. The positive predictive value (PPV) was used to evaluate the performance of NIPT. Results: The screen-positivity rate of NIPT for RCAs was 0.5% (842/158,824). Of the 528 gravidas who underwent amniocentesis, 29.2% (154/528) were confirmed to have positive prenatal SNP array results. PPVs for rare autosomal trisomies (RATs) and segmental imbalances were 6.1% (7/115) and 21.1% (87/413), respectively. Regions of homozygosity/uniparental disomy (ROH/UPD) were identified in 9.5% (50/528) of gravidas. The PPV for clinically significant findings was 8.0% (42/528), including 7 cases with mosaic RATs, 30 with pathogenic/likely pathogenic copy number variants, and 5 with imprinting disorders. Conclusion: NIPT for common fetal aneuploidies yielded low PPVs for RATs, moderate PPVs for segmental imbalances, and incidental findings for ROH/UPD. Due to the low PPV for clinically significant findings, NIPT for common fetal aneuploidies need to be noticed for RCAs.

The complete chloroplast genome sequence of Firmina danxiaensis.

The complete chloroplast genome of Firmina danxiaensis, an important deciduous tree, was identified and sequenced in this study. The genome size is 161,205 bp, the GC content is 36.88%. A total of 129 genes were identified, including 84 protein-coding genes, 8 rRNA genes, and 37 tRNA genes. 10 plastome accessions from Sterculiaceae were selected to assess the phylogenetic placement of genus and the result showed that F. danxiaensis is most closely related to F. simplex.

Identification of copy number variations among fetuses with ultrasound soft markers using next-generation sequencing.

A prospective analysis investigating the associations between pathogenic copy number variations (pCNVs) and ultrasound soft markers (USMs) in fetuses and evaluating the clinical value of copy number variation sequencing (CNV-seq) in such pregnancy studies was carried out. 3,398 unrelated Chinese women with singleton pregnancies and undergone amniocentesis at 18-36 weeks of gestation for fetal CNV-seq were included. According to the prenatal fetal ultrasound screening results, the samples were divided into 3 groups: normal ultrasound (n = 2616), solitary USM (n = 663), and two or more USMs (n = 119). CNV-seq was performed successfully using all samples. The prevalence of pCNVs in fetuses with normal ultrasound and USMs was 3.03% (79/2616) and 2.94% (23/782), respectively. The risk of segmental aneuploidies was significantly higher in the two or more USMs group (5/119, 4.20%) than in the normal ultrasound (27/2616, 1.04%) or solitary USM (9/663, 1.36%) groups (p = 0.002 and p = 0.031, respectively). Assuming that the resolution of karyotyping is ~5 Mb, a cytogenetic analysis would miss 33 of 102 (32.35%) pCNVs in these samples. Our results suggest an association between pCNVs and fetal USMs; multiple USMs indicate an increased risk of fetal segmental aneuploidies. In prenatal diagnostic testing, CNV-Seq identified additional, clinically significant cytogenetic information.