Analysis of Chromosomal Copy Number in First-Trimester Pregnancy Loss Using Next-Generation Sequencing

Abstract

Embryonic chromosomal abnormality is one of the significant causative factors of early pregnancy loss. Our goal was to evaluate the clinical utility of next-generation sequencing (NGS) technology in identifying chromosomal anomalies associated with first-trimester pregnancy loss. In addition, we attempted to provide fertility guidance to couples anticipating a successful pregnancy. A total of 1,010 miscarriage specimens were collected between March 2016 and January 2019 from women who suffered first-trimester pregnancy loss. Total DNA was isolated from products of conception, and NGS analysis was carried out. We detected a total of 634 cases of chromosomal variants. Among the 634 cases, 462 (72.9%) displayed numerical variants including 383 (60.4%) aneuploidies, 44 (6.9%) polyploidies, and 34 (5.5%) mosaicisms. The other 172 (27.1%) cases showed structural variants including 19 (3.0%) benign copy number variations (CNVs), 52 (8.2%) pathogenic CNVs, and 101 (16%) variants of unknown significance (VOUS) CNVs. When maternal age was ≥ 35 years, the sporadic abortion (SA) group showed an increased frequency of chromosomal variants in comparison with the recurrent miscarriage (RM) group (90/121 vs. 64/104). It was evident that the groups with advanced maternal age had a sharply increased frequency of aneuploidy, whatever the frequency of pregnancy loss (71/121 vs. 155/432, 49/104 vs. 108/349). Our data suggest that NGS could be used for the successful detection of genetic anomalies in pregnancy loss. We recommend that fetal chromosome analysis be offered routinely for all pregnancy losses, regardless of their frequency.

Copy number variation characterization and possible candidate genes in miscarriage and stillbirth by next‐generation sequencing analysis

“…The prevalence of aneuploidy and pathogenicity‐associated CNV in aborted fetal tissue was associated with an increased risk of miscarriage in advanced maternal age pregnant women. 21 , 22 , 23 Numerical chromosomal abnormality was the most important reason for embryo termination in early and middle pregnancy, followed by pCNVs. 24 Dai et al .…”

“…The prevalence of aneuploidy and pathogenicity-associated CNV in aborted fetal tissue was associated with an increased risk of miscarriage in advanced maternal age pregnant women. [21][22][23] Numerical chromosomal abnormality was the most important reason for embryo termination in early and middle pregnancy, followed by pCNVs. 24 Dai et al 25 found that the fetal chromosomal abnormality rate in firsttrimester spontaneous abortion was significantly higher than the second-trimester spontaneous abortion.…”

Genetic testing of products of conception in recurrent pregnancy loss evaluation

“…Cytogenetic abnormalities in the POC can be detected by different techniques: conventional G-band karyotyping, fluorescence in situ hybridization (FISH), multiplex ligationdependent probe amplification (MLPA), array comparative genomic hybridization (aCGH), single-nucleotide polymorphism (SNP) microarray and, recently, next generation sequencing (NGS) (Donaghue et al, 2017;Fan et al, 2020;Smits et al, 2020;Wenstrom, 2014). Traditional karyotype testing by G-banding requires tissue culture, can be labour intensive and carries a significant failure rate (approximately 30%), especially when the sample is of poor quality (Donaghue et al, 2010;Sahoo et al, 2017).…”

Stem Cell-Based Trophoblast Models to Unravel the Genetic Causes of Human Miscarriages

“…Karyotype evaluation of first-trimester miscarriages using next-generation sequencing (NGS) found a total abnormality rate of 63%, with 73% numerical variants (including 60% aneuploidies, 7% polyploidies, and 5.5% mosaicisms); the other 27% of cases showed microstructural variants [ 15 ].…”

“…A significant proportion of miscarriages (50–70%) are caused by chromosomal abnormalities; in addition, more data have appeared on the associations between pregnancy loss and copy number variations (CNVs), gene mutations, methylation abnormalities, and other aberrations [ 10 , 11 , 12 , 13 , 14 , 15 ]. One can suggest that the increasing number of studied families and gene variants/CNVs founded in early pregnancy loss highlights the need for their functional assessment in trophoblast development to determine their role in adverse pregnancy outcomes.…”