- Academic Editor
†These authors contributed equally.
Background: To improve the detection rate of chromosome abnormalities
in fetuses and to reduce the birth defects rate in elderly pregnant women using
chromosome karyotype analysis combined with the chromosome microarray analysis
(CMA) technique. Methods: Overall, 210 elderly pregnant women with
singleton pregnancies aged between 16 and 30 weeks (mean gestational age, 19.19
weeks) and 35 and 47 years (mean age, 38.08 years) were selected from January 1,
2020 to June 1, 2021 in the Eugenics Genetics Department of Yulin Maternal and
Child Health Hospital. Chromosome G banding karyotype analysis and CMA detection
were performed simultaneously. Results: Among the 210 elderly pregnant
women with singleton pregnancies, 26 (12.38%) and 52 (24.76%) cases were
detected as abnormal using chromosome karyotype analysis and CMA technology,
respectively. The abnormal CMA chromosomes’ total detection rate was 12.38%
higher than that using chromosome karyotype analysis (p
The proportion of elderly pregnant women (the expected age of delivery
With molecular biology and gene sequencing technology advances, chromosome
microarray analysis (CMA), as a novel prenatal diagnosis method in molecular
genetics, can detect and obtain numerous genome sequences at once within the
entire genome and detect DNA copy number imbalance, that is, copy number variants
(CNVs). It can detect submicroscopic chromosome deletions or duplications
Overall, 210 elderly pregnant women with gestational ages of 16–30 weeks (mean gestational age, 19.19 weeks) and 35–47 years (mean age, 38.08 years) with singleton pregnancies attending the Department of Eugenics and Genetics of Yulin Maternal and Child Health Hospital from 1 January 2020 to 1 June 2021 were selected for both chromosome G ribbon karyotyping and CMA testing. All those who underwent invasive prenatal diagnosis signed an informed consent form before the procedure and were approved by the ethics committee of the unit. All data in this study involving personally identifiable information have been excluded. The inclusion criteria were: (1) Single pregnancy pregnant woman; (2) Age of pregnant woman and expected age of delivery up to 35 years old. Exclusion criteria were: (1) Twins pregnant women; (2) Postoperative reduction of fetus, including surgical reduction of fetus and one of the twins spontaneous abortive.
Briefly, 25 mL of amniotic fluid (20 mL and 5 mL for karyotyping and CMA analysis, respectively) were transabdominally extracted with a 21 GPTC-B puncture needle under ultrasound guidance in advanced maternal age at 16–30 gestational weeks and 35–47 years.
The extracted amniotic fluid was loaded into sterile centrifuge tubes; the amniotic fluid cells were collected by centrifugation and incubated for 10–14 d in applanation until the cells were in good growth condition. Colchicine was added, and cells were collected for routine filming. G bands (320–400 bands) were revealed for karyotype analysis and automatically scanned using the American Leica fully automated scanning microscope and image analysis system. They were analyzed on the GSL-120 fully automated workstation analysis software, counting 20 mid-phase divisions and analyzing 5 karyotypes, and doubling the analysis and counting of divisions for abnormalities. Karyotype descriptions were referenced using the International System of Nomenclature for Human Cytogenomics (ISCN 2016).
The extracted amniotic fluid DNA was assayed for CNV using Cy5-labeled samples and Cy3-labeled controls; equal amounts of different fluorescent-labeled DNA and reference DNA to be tested were hybridized simultaneously to microarrays comprising OligoDNA probes after being fixed with non-specific-repetitive sequences using human Cot-1DNA and hybridized for 24 hours. Subsequently, the whole genome scan was detected using a chromosome microarray chip produced by Agilent (Palo Alto, CA, USA), and the results were analyzed by data analysis using Agilent Genomic Workbench software (Palo Alto, CA, USA) to calculate the genotype or relative intensity of the signal generated for each locus. The results were queried in the Online Mendelian Inheritance in Man (OMIM), University of California Santa Cruz (UCSC), International Standards for Cytogenomic Arrays (ISCA), Database of Genomic Variants (DGV), DatabasE of Chromosomal Imbalance and Phenotype in Humans using Ensembl Resources (DECIPHER) databases and other databases. DNA CNVs of the genome were classified into the following four categories according to the American College of Medical Genetics and Genomics guidelines issued in 2015: (a) clinically pathogenic CNVs; (b) probable clinically pathogenic CNVs; (c) CNVs of unknown clinical significance; and (d) benign CNVs.
Statistical Package for Social Sciences (SPSS) version 26.0 (IBM Corp., Armonk,
NY, USA) software was used for statistical analysis, and the count data were
expressed as rate and frequency, and the
Among 210 pregnant women of advanced maternal age, 26 karyotypic abnormalities were detected, with an overall detection rate of 12.38% (26/210). Of these, 16 cases of chromosomal aneuploidy were detected, with a detection rate of 7.62% (16/210), including 6 cases of trisomy 21, 6 of chimerism, 2 cases of 47,XXY, 47,XYY, and 47,XXX,inv(9)(p12q13) each; 10 cases of chromosomal structural abnormalities, with a detection rate of 4.76% (10/210), including 5 cases of inversions, 3 of translocations, 1 of duplications and deletions each; and 14 cases of chromosomal polymorphisms (6.67%), excluded from the karyotyping of chromosomal abnormalities in this study (See Table 1).
Classification | Number | Incidence (%) | |
Number abnormalities | 16 | 7.62 | |
47,Xn,+21 | 6 | 2.85 | |
47,XXY | 2 | 0.95 | |
47,XXX,inv(9)(p12q13) | 1 | 0.48 | |
47,XYY | 1 | 0.48 | |
Chimera | 6 | 2.86 | |
Structural abnormalities | 10 | 4.76 | |
inv | 5 | 2.38 | |
dup | 1 | 0.48 | |
t | 3 | 1.43 | |
del | 1 | 0.48 | |
Polymorphism | 14 | 6.67 |
Note: N in the table represents chromosome X or Y. Inv, inversion; T, translocation; Del, deletion; Dup, duplication.
Among 210 pregnant women with advanced maternal age, 52 cases of chromosomal abnormalities were detected, with a total chromosomal abnormality detection rate of 24.76% (52/210), including 17 cases of chromosomal aneuploidy and 35 cases of copy number variation. Among the 17 cases of aneuploidy abnormalities, 6 and 4 cases of trisomy 21 and sex chromosome aneuploidy abnormalities, respectively, were found as follows: 1 case of 47,XXX, but the karyotype analysis result was 47,XXX,inv(9)(p12q13); 2 of 47,XXY; 1 of 47,XYY; and 7 of chimerism. Of the 35 CNVs, 27 were clinically pathogenic CNVs (25 microdeletions and 2 microduplications); 1 was a probable clinically pathogenic CNV (microdeletion); 7 were CNVs of unknown clinical significance (microduplications) (See Table 2).
Classification | Number | Incidence (%) | |
Number abnormalities | 17 | 8.09 | |
Trisomy 21 | 6 | 2.85 | |
Sex chromosome aneuploidy | 4 | 1.90 | |
Chimera | 7 | 3.33 | |
Copy number variations | 35 | 16.67 | |
Pathogenic | 27 | 12.86 | |
Like pathogenic | 1 | 0.48 | |
Clinical significance unknown | 7 | 3.33 |
Among the 17 cases of aneuploidy abnormalities detected using CMA, 6 and 4 cases of abnormal autosomal number and sex chromosome number were detected. These were consistent with the karyotype analysis. Seven cases of chimerism were detected, six of which were consistent with the karyotype analysis, and one additional case of chimerism was detected using CMA, whose karyotype result was 46,Xn,1qh+. The result of CMA was 46,XX/46. Furthermore, the chimerism of 46,XY (~15% of 46,XX) was detected using CMA, and the two results were inconsistent (See Tables 2,3).
Number | Karyotype results | CMA result | Outcome | Classification | Pregnancy outcomes | ||
A202246 | No abnormality | arr[GRCh37]22q11.21(18919528_20943564)x3 | 22q11.21 has about 2.02 Mb of duplication | pCNVs | BH/LB | ||
A202677 | No abnormality | arr[GRCh37]17q12(34438350_36207539)x1 | The 17q12 region has a deletion of approximately 1.77 Mb, a pathogenic copy number variant. 17q12 deletion syndrome, also known as Renal Cysts and Diabetes Syndrome (RCS) | pCNVs | BH/LB | ||
A204280 | No abnormality | arr[GRCh37]Xq28(152419166_153330005)x2 | Xq28 has about 910.84 kb repeats | pCNVs | TOP | ||
A210791 | 46,Xn,15pstk+ | arr[GRCh37]5p15.33p15.31(55550-8129512)x1,10p15.3p15.(138878-4817952)x3 | 5p15.33p15.31 has a deletion of approximately 8.07 Mb, which overlaps most of the region with cri-du-chat syndrome (also known as catcalling syndrome). | pCNVs | TOP | ||
A203673 | No abnormality | arr[GRCh37]22q11.21(18919528_21417548)x1 | 22q11.21 has about 2.5 Mb deletion | pCNVs | TOP | ||
A204246 | No abnormality | arr[GRCh37] 22q11.21(21007827_21417548)x1 | 22q11.21 approximately 409 kb deletion, possibly pathogenic. | LpCNVs | TOP | ||
A204001 | No abnormality | arr[GRCh37] 16p13.11(15125829_16287899)x3 | 16p13.11 has about 1.16 Mb of duplicates | VOUS | BH/LB | ||
A203157 | No abnormality | arr[GRCh37] 5q11.1q11.2(49986122_51806250)x3 | 5q11.1q11.2 has about 1.82 Mb of duplicates | VOUS | BH/LB | ||
A200911 | No abnormality | arr[GRCh37] 8q22.2(99556452_100587077)x3 | 8q22.2 has about 1.03 Mb of duplication | VOUS | BH/LB | ||
A201435 | No abnormality | arr[GRCh37]16p13.11p12.3(15512480_18128488)x3 | 16p13.11p12.3 approx. 2.62 Mb repeat | VOUS | BH/LB | ||
A200982 | No abnormality | arr[GRCh37] 12q21.31(81698253_83380025)x3, 16p12.2(21950360_22428364)x1 | A duplication of approximately 1.68 Mb was present in 12q21.31, a copy number variant of unknown clinical significance, a deletion of approximately 478 kb was present in 16p12.2, involving the 16p12.2 deletion region of unknown significance. | VOUS | BH/LB | ||
A210631 | No abnormality | arr[GRCh37]16p13.11p12.3(15512480-1812488)x3 | 16p13.11p12.3 has about 2.62 Mb of repeats. | VOUS | BH/LB | ||
A210950 | No abnormality | arr[GRh37]16p13.3(215499-232685x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A201005 | No abnormality | arr[GRCh37]16p13.3(215499_232685)x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A201110 | No abnormality | arr[GRCh37]16p13.3(215499_232685)x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A211238 | No abnormality | arr[GRh37]16p13.3(215499-232685x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A200068 | No abnormality | arr[GRCh37]16p13.3(215499-232685)x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | LB/hallux varus of the feet | ||
A200073 | No abnormality | arr[GRCh37]16p13.3(215499-232685)x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A200111 | No abnormality | arr[GRCh37]16p13.3(215499-232685)x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A200980 | No abnormality | arr[GRCh37]16p13.3(215499_232685)x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A210281 | No abnormality | arr[GRCh37]16p13.3(215499-232685)*1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A210304 | No abnormality | arr[GRCh37]16p13.3(215499-232685)*1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A201504 | No abnormality | arr[GRCh37]16p13.3(215499_232685)x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A201979 | No abnormality | arr[GRCh37]16p13.3(215499_232685)x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A202357 | No abnormality | arr[GRCh37]16p13.3(215499_232685)x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A202573 | No abnormality | arr[GRCh37]16p13.3(215499_232685)x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A203094 | No abnormality | arr[GRCh37]16p13.3(215499_232685)x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A203268 | No abnormality | arr[GRCh37]16p13.3(215499_232685)x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | TOP | ||
A203884 | No abnormality | arr[GRCh37]16p13.3(215499_232685)x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A210247 | 46,Xn,inv(3)(p11.2q25.3)mat | arr[GRCh37]16p13.3(215499-232685)x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A210331 | 46,Xn,t(10;14)(p14;q12) | arr[GRCh37]16p13.3(215499-232685)x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A202837 | 46,Xn,inv(9)(p12q13) | arr[GRCh37]16p13.3(215499_232685)x1 | 16p13.3 has a heterozygous deletion of about 17.19 kb | pCNVs | BH/LB | ||
A204091 | 46,Xn,t(7;11)(q11.2;p11.2) | arr[GRCh37]3q29(195769570_197127658)x1 | 3q29 has a deletion of about 1.36 Mb | pCNVs | TOP | ||
A200428 | 45,X[18]/46,X,del(X)(p21.1) | arr[GRCh37]16p13.3(215499_232685)x1,Xp22.33p22.13(1_18240143)x1 | Xp22.33p22.13 has a heterozygous deletion of about 18.24 Mb, which is a pathogenic copy number variant. | pCNVs | TOP | ||
A202255 | 46,Xn,1qh+ | arr(X)x1 2,(Y)x0 1 | Suggests an abnormal sex chromosome ratio, presumably there may be a 46,XX/46,XY chimerism in this sample (the proportion of 46,XX is about 15%) | Chimera | BH/LB | ||
A202545 | 46,Xn,dup(14)(q24.3q32.1) | arr[GRCh37]14q24.3q32.12(77521398_94319728)x3 | 14q24.3q32.12 There is a duplication of approximately 16.8 Mb, the clinical significance of which is unknown. | VOUS | BH/LB | ||
A200826 | 46,Xn,t(5;22)(p10;q10)pat | arr(1-22)x2,(X,N)x1 | No abnormality | normal | BH/LB | ||
A201648 | 46,Xn,del(22)(p10) | arr(1-22)x2,(X,N)x1 | No abnormality | normal | BH/LB | ||
A211168 | 46,Xn,inv(3)(p24p26) | arr(1-22)x2,(X,N)x1 | No abnormality | normal | BH/LB | ||
A211267 | 46,Xn,inv(9)(p12q13) | arr(1-22)x2,(X,N)x1 | No abnormality | normal | BH/LB | ||
A211329 | 46,Xn,inv(12)(p13q15)mat | arr(1-22)x2,(X,N)x1 | No abnormality | normal | BH/LB |
Note: CMA, chromosome microarray analysis; pCNVs, pathogenic CNVs; LpCNVs, likely pathogenic CNVs; VOUS, variants of uncertain significance; TOP, termination of pregnancy; LB, live birth; BH, born healthy.
The CMA detected 27 pathogenic CNVs, with an abnormality rate of 12.86% (27/210), of which 22 had no chromosomal abnormalities, whereas pathogenic CNVs were detected using CMA, i.e., in addition to the abnormal cases detected using the karyotype analysis, the CMA detected 22 additional pathogenic CNVs, accounting for 10.48%. The karyotype results of the other 5 pathogenic CNVs were 2 inversions: 46,Xn,inv(3)(p11.2q25.3) mat and 46,Xn,inv(9)(p12q13); 2 translocations: 46,Xn,t(10;14)(p14;q12) and 46,Xn,t(7;11)(q11.2;p11.2); and 1 case is a chimera: 45,X[18]/46,X,del(X)(p21.1) (See Tables 2,3).
One case was detected without abnormal karyotype and a CMA test result of 22q11.21, ~409 kb deletion that may be pathogenic, at a 0.48% (1/210) detection rate (see Tables 2,3).
The CMA detected 7 CNVs of unknown clinical significance, accounting for 3.33% (7/210); 6 of the 7 cases of unknown clinical significance had no abnormal karyotype results, and 1 karyotype was 46,Xn,dup(14)(q24.3q32.1); the CMA result was 14q24.3q32.12 with a duplication of ~16.8 Mb, which was of unknown clinical significance. However, the clinical significance was unclear (See Tables 2,3).
Five cases with normal CMA and abnormal karyotype results were found, which were three with chromosomal inversions, one with chromosomal translocation, and one with chromosomal deletion (Table 3).
Overall, 52 (24.76%) and 26 (12.38%) cases of abnormalities were detected
using CMA alone and karyotype analysis alone, respectively. Among them, there
were 21 cases with abnormal chromosomes that could be detected by both methods,
but 31 cases with abnormal chromosomes detected by CMA could not be detected by
karyotype analysis, and 5 cases with normal karyotype results but abnormal CMA
results. Kappa consistency test was used for analysis, and the result was Kappa =
0.447, p
CMA | Karyotype analysis | Total | |
Abnormality | Normal | ||
Abnormality | 21 | 31 | 52 |
Normal | 5 | 153 | 158 |
Total | 26 | 184 | 210 |
CMA, chromosome microarray.
Moreover, the rates of fetal chromosomal abnormalities detected by chromosome
karyotype analysis alone, CMA alone, and chromosome karyotype analysis combined
with CMA were 12.38%, 24.76%, and 27.14%, respectively. The difference among
the three groups was statistically significant (
Group | Normal cases | Abnormal cases | Detection rate |
Karyotype analysis | 184 | 26 | 12.38% |
CMA | 158 | 52 | 24.76% |
Karyotype analysis combined with CMA | 153 | 57 | 27.14% |
CMA, chromosome microarray.
Among the 210 pregnant women with detected fetal chromosomal abnormalities, genetic counseling was performed. Among the pregnant women with abnormal chromosome numbers, 3 chimeric cases chose to continue delivery, and the fetuses were born with no significant abnormalities in appearance; Labor induction was performed in 6 cases of trisomy 21, 2 cases of 47,XXY, 1 case of 47,XYY, 1 case of 47,XXX,inv(9)(p12q13) and 4 cases of chimeric fetus.
The results of 28 pregnancies with pathogenic or probable pathogenic CNVs were as follows: 1 case of 5p15.33p15.31 with ~8.07 Mb deletion, 1 case of CMA suggesting 3q29 with ~1.36 Mb deletion and karyotype 46,Xn,t(7;11)(q11.2;p11.2), and 1 case of 22q11.21 with ~409 kb deletion where 1 case of 22q11.21 had a deletion of ~2.5 Mb, and was induced after a lineage analysis suggesting a new mutation. One case of 16p13.3 had a heterozygous deletion of ~17.19 kb and was selected to continue delivery after a lineage analysis suggesting maternal inheritance, and the fetus was born without abnormalities; one case of Xq28 had a duplication of ~910.84 kb and was induced after a lineage analysis suggesting maternal inheritance. One case suggested severe thalassemia fetus and induced labor.
Seven CNVs of unknown clinical significance were followed up: one case with a duplication of ~1.03 Mb at 8q22.2, and the family chose to continue the pregnancy after a lineage analysis suggesting a new mutation; one with a duplication of ~2.62 Mb at 16p13.11p12.3, and the family chose to continue the pregnancy after a lineage analysis suggesting maternal inheritance; and one case with a duplication of ~16.8 Mb at 14q24.3q32.12 In one case, duplication of 14q24.3q32.12 was found with ~16.8 Mb. All seven fetuses with CNVs of unknown clinical significance were delivered alive at follow-up, and no significant abnormalities were observed at birth.
The proportion of elderly pregnant women has increased with the opening of the
second- and third-child policies. The older the pregnant woman is, the higher the
risk of birth defects. Some studies show that the incidence of fetal aneuploidy
and birth defects in elderly pregnant women are significantly higher than those
in young women, and the rate of chromosome abnormality increases gradually with
the increasing age [6]. Advanced age is an important indicator of prenatal
diagnosis and also a high-risk factor for fetal chromosome abnormalities [7].
This study uses chromosome karyotype analysis combined with the CMA technique to
examine the chromosomes of amniotic fluid samples of elderly pregnant women.
Currently, chromosome karyotype analysis is the gold standard in the clinic for
detecting fetal chromosome abnormalities, which can detect chromosome number and
structural abnormalities ˃10 Mb. CMA currently has two detection techniques as
follows: comparative genomic hybridization (CGH) and single nucleotide
polymorphism (SNP). CGH is the main clinical CMA technology. Most CGH chips used
in prenatal diagnosis are targeted microarrays designed for chromosome
aneuploidy, typical microdeletions or microrepeats, and subtelomere or other
chromosome structural rearrangements of obvious clinical significance. Compared
with CGH, SNP uses arrays based on high-density oligonucleotides and can extract
other clinically useful information from the genotype map. This includes single
parent diploid, chimera, maternal cell contamination, and blood relationship, and
can also identify triploids CGH cannot detect [8]. Here, amniocentesis,
chromosome karyotype analysis, and CMA detection were performed in 210 elderly
pregnant women. Overall, 26 cases of abnormal karyotypes were detected using
chromosome karyotype analysis, with a detection rate of 12.38% (26/210). The
total detection rate of CMA chromosome abnormalities was 24.76% (52/210), which
was 12.38% higher than that of karyotype analysis. It is significantly higher
than that reported by Shaffer et al. [9]. that CMA can increase the
abnormal detection rate by 2.9% compared with chromosome karyotype analysis.
However, 3.6% more chromosomal abnormalities can be detected than in traditional
karyotype techniques; this is higher than that in the CMA technique reported by
Hillman et al. [10]. The reason for the analysis may be that the cases
in this study are elderly pregnant women and some elderly pregnant women also
combine some high-risk factors, and old age will also increase the rate of
chromosome abnormality. Second, there are more thalassemia gene carriers because
Guangxi belongs to the high incidence area of thalassemia, resulting in a higher
detection rate of pathogenic CNV. For chromosome number abnormalities, 16 cases
of pathogenic chromosome aneuploidy were detected using CMA and karyotype
analysis, including 6, 4, and 6 cases of trisomy 21, sex chromosome aneuploidy,
and chimerism, respectively. CMA also detected an additional case of chimerism.
The karyotype analysis result was 46 Magi Xnjue 1qhmage, whereas that of the CMA
test was 46 Magi XXB and 4Q XY chimerism (the proportion of 46 Magi XX was
~15%); however, the two results were inconsistent. Based on the
karyotype analysis, 22 additional cases of pathogenic CNV were detected using
CMA, with an additional detection rate for pathogenic CNV of 10.48%, similar to
the results of Srebniak et al. [11] and Van den Veyver et al.
[12]. An Indian study indicated [13] that compared with karyotype analysis, Cmas
detected an additional 3.78% copy number variation in pathogenicity and detected
3 pCNVs (13.04%) among 23 maternal age high schools. It is lower than the result
of our study, which may be attributed to the fact that our study mainly targeted
at older pregnant women and did not subdivide other indicators of prenatal
diagnosis, leading to bias. In pregnant women who received amniotic fluid
puncture with no ultrasound abnormalities, simple old age or positive aneuploidy
screening, chromosome microarray analysis detected pathogenic CNVs in only 1.7%
of cases [8, 14]. Wapner et al. [15] also reported 20 cases of genetic
abnormalities that were not found using karyotype analysis. Of the 20 cases,
9.3% and 11.3% of pregnant women were found with chromosome abnormalities of
clinical significance and uncertain clinical significance, respectively. However,
CMA can not detect some balanced chromosome structural abnormalities such as
balanced translocation, inversion, insertion, and gene point mutation [16]. Some
studies have shown that the traditional G-banding karyotype analysis can detect
abnormalities undetected using 3% CMA. Here, 5 cases were found with normal CMA
results but abnormal using chromosome karyotype, including 1, 1, and 3 cases of
chromosome translocation, deletion, and inversion, respectively, accounting for
2.4%, which was close to the foreign-related studies [17, 18]. Studies have
shown that balanced translocation and inversion of chromosomes are important
causes of reproductive abnormalities, and the rate of chromosomal abnormalities
in full-term fetuses of couples carrying balanced translocation is about 10%,
higher than that of the general population [19]. Balanced translocation is also
associated with repeated abortion [20]. In our study, the abnormal rate of
karyotype analysis combined with CMA detection was 27.14% (57/210), which was
higher than that of CMA or chromosome karyotype analysis alone. The results of
chromosome karyotype analysis combined with CMA were statistically significant
compared with those of chromosome karyotype analysis alone (p
The results of 22 cases with no abnormalities in chromosomal testing and pathogenic CNV results in CMA, case A202246, were analyzed, and duplication of ~2.02 Mb was detected in sample 22q11.21, a pathogenic CNV. This duplication overlaps with the 22q11.2 duplication region, and the ClinGen database was queried to find a clear triple dose effect for the 22q11.2recurrent DiGeorge/palatine facial syndrome (DGS/VCFS) region (proximalA-B, chr22:18,912,231-20,287,208), and the individuals carrying this duplication have varying clinical symptoms. The 22q11 repeat is inherited from phenotypically normal or near-normal parents in ~70% of cases. Rosenfeld et al. [21] performed a Bayesian analysis of data from a large sample of people and showed that the 22q11.2 microrepeat has ectopic incompleteness with an ectopic rate of ~21.9%. This study’s patient had a history of adverse pregnancy and delivery with two embryonic stoppages; we performed CMA on the peripheral blood of the parents, but the microarray analysis did not reveal any clinically significant chromosomal abnormalities, and the pregnant fetus was born with pathological jaundice without significant abnormalities in appearance and is currently growing well.
A202677 detected a deletion of ~1.77 Mb in the 17q12 region of the sample, a pathogenic copy number variant. This deletion region is involved in 17q12 deletion syndrome, also known as renal cysts and diabetes syndrome; the key gene is HNF1B, which is expressed in all renal tubular epithelial cells that constitute the renal units and collecting ducts, controls and participates in membrane transport, cellular differentiation, and expression of metabolic genes, and has a role in the regulation of important renal genes such as PKHD1 and PKD2 [22]. The clinical presentation of patients with this syndrome varies widely among individuals, with the main clinical features including abnormal kidney or urogenital development (polycystic kidney, renal insufficiency), diabetes in late adolescence (MODY5), neurodevelopmental/neuropsychiatric disorders (autism, schizophrenia, anxiety, and epilepsy), developmental delay, language backwardness, and mental retardation. 17q12 deletion syndrome is dominantly inherited, with 70% and 30% of deletions being de novo variants and inherited from the parents, respectively, and the epistatic rate of 34.4%. A study [23] showed a significant correlation between enhanced renal parenchymal echo and 17q12 microdeletion syndrome. Quintero-Rivera et al. [24] reported the first case of duodenal atresia associated with 17q12 microdeletion revealing for the first time that the phenotypic spectrum of 17q12 microdeletion syndrome should include duodenal atresia. Here, the case patient had fetal ultrasound findings of bilateral renal pelvis separation, and the fetal outcome at gestational follow-up was a healthy boy delivered alive without significant abnormalities.
A204280 detected an ~910.84 kb duplication in sample Xq28, a pathogenic CNV. This duplication is involved in Xq28 duplication syndrome with the key gene MECP2, which is an X-linked neurodevelopmental disorder where patients exhibit severe psychomotor retardation, hypotonia, language development disorders, progressive muscle spasms, various seizures, and in some cases, developmental regression, ataxia, choreiform movements, sleep disorders, and recurrent respiratory infections. Males are 100% ectopic, whereas female carriers are usually unaffected or show only psychoneurological abnormalities. Subsequent lineage analysis suggested maternal inheritance, and the fetal sample Xq28 with ~910.84 kb of repeat inheritance from the mother was confirmed through CMA analysis, followed by selection for labor induction.
A210791 detected a deletion of ~8.07 Mb in sample 5p15.33p15.31, a pathogenic CNV. The deletion overlaps most of the region with the cri-du-chat syndrome (also known as catcalling syndrome), which has multiple pathogenic and possibly pathogenic reports in DECIPHER and ClinVar databases. The clinical phenotypes of these patients include intrauterine growth retardation, prematurity, feeding difficulties, short stature, peculiar facial features, mental retardation, and voice abnormalities; the deletion region contains 41 proteins, including TERT. The gene encoding TERT was mentioned in the ClinGen database as possibly having a single-dose effect (Haploinsufficiency Score: 1), but the evidence was insufficient. A duplication of 4.68 Mb was also detected in sample 10p15.3p15.1, of unknown clinical significance. This duplication was queried in the patient databases, DECIPHER and ClinVar, for 3 cases of (probable) pathogenicity reported and unqueried in the general population database, DGV; this region contains 12 protein-coding genes, including IDI2, and the ClinGen database was unqueried for the above gene/region duplication dose effect. The pregnancy outcome in this pregnancy was direct induction of labor.
A203673 detected ~2.5 Mb deletion in the sample 22q11.21, which was a pathogenic CNV. This deletion involves 22q11.2 deletion syndrome, which is mainly classified into three subtypes as follows: DGS syndrome (#188400), VCFS(#192430), and vertebral shaft abnormal facial syndrome (CAFS). Among them, DGS is mainly characterized by congenital heart disease, immunodeficiency, and hypocalcemia and is common in newborns; VCFS mainly shows cleft palate, congenital heart disease, special face, slender fingers, and mental and behavioral abnormalities, among others; CAFS mainly shows special face and heart deformities. This female patient had a history of adverse pregnancy with billet abortion, and a genealogical analysis suggested that this mutation was a de novo mutation, and the fetus was induced.
Another 17 cases detected a heterozygous deletion of ~17.19 kb
in sample 16p13.3, a pathogenic CNV. This deletion contained at least 4 OMIM
genes, including HBM, HBA2, HBA1, and HBQ1,
of which HBA1 and HBA2 are key genes for
Here, seven cases of CNV of unknown clinical significance were detected, and all seven fetuses with CNVs of unknown clinical significance were delivered alive. In our study, 7 cases with unknown clinical significance accounted for 3.33% of CNVs, higher than the result of a foreign study of 1.89% [13]. This is consistent with the report of another foreign study that VOUS accounts for no more than 5% [25]. In the case of CNVs of unknown significance, it has been suggested that this may cause significant stress and even panic among pregnant women and their families and may lead to unnecessary labor induction in some cases. Therefore, the clinical indications for prenatal diagnosis are strictly defined before performing CMA, the pregnant women and their families are fully informed of the possible outcome, and consent is obtained. Furthermore, genetic counseling is adequately conducted before the prenatal diagnosis is performed [26]. In addition, most of the older pregnant women are the second child or more, so the proportion of cesarean section is larger, further increasing the risk of pregnancy. Recently, Vimercati et al. [27] used an innovative ultrasound parameter to measure the level of scar-vesicovaginal fold distance to determine the risk of uterine rupture in pregnant women. Combined with prenatal diagnosis, this method will better predict the occurrence of adverse pregnancy outcomes.
Summarily, the detection rate of chromosome abnormalities in CMA was significantly higher than that in the routine karyotype analysis if the CMA technique was used alone in this study. However, CMA will miss some chromosomes with structural abnormalities, such as chromosome translocation and inversion, which may cause the risk of infertility and miscarriage [28]. Here, the effect of CMA in detecting chromosome aneuploidy variation is similar to that of chromosome karyotype analysis. CMA has more advantages in detecting chromosome microdeletions and microrepeats; therefore, CMA detection is recommended for elderly pregnant women, regardless of whether they are combined with other indications, but CMA can not identify some chromosome structural abnormalities such as chromosome translocation, inversion, and insertion, among other. Since CMA cannot replace karyotype analysis, it is suggested that CMA should be combined with various detection methods.
For the prenatal diagnosis of fetal amniotic fluid in elderly pregnant women, the combined application of chromosome karyotype analysis and CMA detection technology can further improve the detection rate of abnormal chromosomes and reduce the rate of missed diagnosis, thus, reducing the birth defects rate and achieving the goal of eugenics.
The data used to support the findings of this study are included within the article.
GTL, CO and WWL designed the research study. CO and WWL provided the idea for the research. GTL and WWL analyzed the data and performed the literature search. GTL, CO and WWL provided oversight and were responsible for the study organization and implementation, and writing of the manuscript. GTL, CO and WWL revised the manuscript’s intellectual content. All authors contributed to editorial changes in the manuscript. All authors read and approved the final manuscript.
All those who underwent invasive prenatal diagnosis signed an informed consent form before the procedure and were approved by the ethics committee of Medical Ethics Committee of Yulin Maternal and Child Health Hospital (Approval number: YLSFYLL2021-04-29-04). The sample-related data analyzed for this manuscript was entirely retrospective with no patient or patient-related identifiers included in the analysis.
We thank the staff in the Yulin Maternal and Child Health Hospital and Perkin Elmer Co., Ltd for their assistance in conducting this clinical research study.
This research received no external funding.
The authors declare no conflict of interest. We declare there is no conflict of interest between this research and Perkin Elmer Co., Ltd.
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