Clinical application of chromosomal karyotype analysis combined with chromosomal microarray analysis in the prenatal diagnosis of pregnant women with advanced maternal age

doi:10.21203/rs.3.rs-2837368/v1

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Clinical application of chromosomal karyotype analysis combined with chromosomal microarray analysis in the prenatal diagnosis of pregnant women with advanced maternal age

https://doi.org/10.21203/rs.3.rs-2837368/v1

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Background This study aimed to investigate the clinical application value of chromosome karyotype analysis and union chromosome microarray analysis (CMA) in the prenatal diagnosis of pregnant women with advanced maternal age.

Method A total of 228 pregnant women who received invasive prenatal diagnosis due to advanced age in the Medical Genetics Department of Pingxiang Maternal and Child Health Hospital, Jiangxi Province, China from January 2021 to June 2022 were retrospectively analyzed. Results of chromosome karyotype analysis and CMA were compared.

Results (1) Chromosome karyotype analysis was performed in 228 elderly pregnant women, among which 213 were normal. Abnormal karyotype was found in 15 cases. (2) Among 228 elderly pregnant women, 211 had normal CMA results and 17 had abnormal CMA results. A total of 32 abnormal cases were detected by chromosome karyotype analysis combined with CMA. (3) A total of 15 cases had abnormal karyotype, only 6 cases had abnormal CMA results, and the coincidence rate of abnormal detection rate of the two methods was 40%.(4) Chromosome inversion, translocation, chimera, and polymorphism were not abnormal in CMA.

Conclusion The above two methods had advantages and disadvantages. Karyotype analysis and microarray analysis technology can effectively improve the detection rate of abnormalities in the prenatal diagnosis of older pregnant women. This finding suggested that clinicians should comprehensively analyze various influencing factors, conduct reasonable genetic counseling, and combine the two methods of analysis to improve the detection rate of fetal abnormalities and prevent birth defects in newborns.

Chromosome karyotype analysis

Chromosome microarray analysis

Prenatal diagnosis

advanced age

In 1956, TJIO and Levan et al. found that the number of human chromosomes was 46 [1]. With the application of chromosome G banding, karyotype analysis was regarded as the gold standard for prenatal diagnosis [2]. It can detect major chromosomal abnormalities, such as aneuploidy, unbalanced rearrangement, and Robertson chromosomes. Chromosome is the carrier of genetic material, and its abnormal number and structural distortion leads to increased or decreased gene expression, resulting in the abnormality of body morphology and function. Chromosomal diseases include number and structure abnormalities, and their incidence rate in fetuses is about 0.1–0.2%[3]. Most chromosomal diseases cannot be treated, which is one of the important reasons leading to the rate of birth defects. Prenatal diagnosis, also known as intrauterine diagnosis, refers to the diagnosis of sick individuals by various methods before birth [4]. Indications include the following: 1) older pregnant women over 35 years of age; 2) if a couple has a normal chromosome composition but has already given birth to one or more children with abnormal chromosomes, then prenatal diagnosis is required for a second pregnancy; 3) prenatal diagnosis is required if one of the couple has chromosomal abnormalities; 4) Prenatal diagnosis should be performed if a certain genetic disease exists in the family, which can be confirmed by biochemical analysis or DNA analysis; 5) certain X-linked genetic diseases; and 6. other special types of pregnant women, such as those with early exposure to teratogenic, mutagenic, and carcinogenic agents, early use of suspicious drugs, and intrauterine fetal growth retardation.

Chromosome microarray analysis (CMA) is used to hybridize a large number of probe molecules fixed on the carrier with labeled sample molecules,. The number of sample molecules (copy number variations, CNVs) and sequence information (SNP) is obtained by detecting the hybridization signal intensity of each probe molecule [5]. CMA can improve the submicroscopic imbalance or CNVs of the fetus, and CMA technology is extensively applied in prenatal diagnosis [5].

This project aimed to screen out elderly pregnant women who met the research conditions in the prenatal diagnosis clinic of our hospital, performed amniotic fluid puncture for CMA detection and chromosome karyotype analysis, and explored the clinical application value of chromosome karyotype analysis combined with CMA in the prenatal diagnosis of elderly pregnant women.

Subjects

Object A total of 228 elderly pregnant women admitted to the Medical Genetics Department of Pingxiang Maternal and Child Health Hospital (hereinafter referred to as "our Hospital") from January 2021 to June 2022 were selected for chromosome karyotype analysis and chromosomal microarray detection. The pregnant women were 35–46 years old, with an average age of 38.1 ± 2.6 years old, and the gestational age of the fetus was 18–24 weeks. The average was 18.3 ± 2.3 weeks. The pregnant woman was in good health and had no medical complications. Patients with acute chronic disease or congenital heart disease were excluded. This study obtained the informed consent of the patients, as well as the review and approval of the hospital's medical Ethics Committee.

Method Preoperative genetic counseling and specimen collection were conducted as follows. Before invasive prenatal diagnosis, patients who met the indications for prenatal diagnosis received genetic counseling as necessary and provided their consent after being infored of the risks. Under ultrasound guidance, 30 mL of amniotic fluid was extracted by amniocentesis and divided into three tubes. About 20 mL was sent to the genetic laboratory for karyotype analysis, and the other 10 mL was sent to the Medical Genetics Center of Jiangxi Maternal and Child Health Hospital in China for CMA detection. Chromosome karyotype analysis was performed as follows. Two tubes of 20 mL of amniotic fluid were collected for routine amniotic cell culture (line 2) and chromosome karyotype preparation. The amniotic fluid was centrifuged and then the supernatant was removed and inoculated in a 5% CO₂ incubator at 37 ℃ for culture. After observing cell growth, the fluid was changed, autumn was added, harvest was made, and Giemsa was dried by a hair dryer. A ZEISS Aixo Imager.Z2 automatic scanner was used to capture chromosome karyotypes. Using the International Nominational System for Human Cytogenetics (ISCN2016) as the diagnostic criteria for karyotype analysis, the ZEISS chromosome karyotype analysis software was used to count 20 metaphase cell chromosome karyotypes, with a total of 3 karyotypes per line and 6 karyotypes in 2 lines. If abnormal karyotypes existed, the count or amount of analysis was increased. For CMA detection, 10 mL of amniotic fluid was collected and sent to the Medical Genetics Center of Jiangxi Provincial Maternal and Child Health Hospital in China for CMA. CMA was conducted using a large number of probe molecules fixed on the carrier and hybridized with labeled sample molecules. The number (CNV) and sequence information (SNP) of sample molecules were obtained by detecting the hybridization signal strength of each probe molecule. Based on Affymetrix Cytoscan 750K chips, CMA was capable of copy number variation (CNVs) ≥ 400 kb (≥ 50 markers), homozygous status (ROH) ≥ 10 Mb, and probe locations of 22 autosomal and sex chromosome pairs. These results were based on the Human Cytogenetic International Nomenclature System. By searching DGV, ISCA, DECIPHER, OMIM, UCSC, and other databases, as well as a peer comparison database, CNVs were classified into pathogenicity, polymorphism, probable pathogenicity, and unknown significance. The internal laboratory database reported the variation in the lower limit of the principle and was reported as appropriate according to the importance of its mutation site. After the research data were collected and collated, statistical analysis was completed using SPSS 23.0 software. The count data were presented in the form of [example (%)] and were compared by X2 test with a test level of 0.05.

Chromosomal karyotype analysis detected abnormalities

Chromosome karyotype analysis was performed in 228 elderly pregnant women, among which 213 were normal. There were 15 abnormal karyotypes (6.58%), including 2 cases of trisomy 18 syndrome (2/15, 13.3%), 3 cases of trisomy 21 syndrome (3/15, 20%), 1 case of Turner syndrome (45, X) (1/15, 6.7%), and 3 cases of chromosomal inversion (3/15, 20%). There were 2 cases (2/15 13.3%) of chromosomal translocation, 1 case (1/15, 6.7%) of chromosomal low comparison chimera, 2 cases (2/15, 13.3%) of chromosomal polymorphism, and 1 case (1/15, 6.7%) of derived chromosome (Table 1).

Table 1

Abnormal chromosome karyotype in the amniotic fluid of 15 elderly pregnant women (n = 15)
Sample number	Medical reasons	Karyotypes	Cases	Pregnancy outcome
1	Advanced age, and NT:3.4 mm	47, XN, + 18	1	Induced abortion
2	Advanced age, NIPT suggests a high risk of trisomy 18	47, XN, + 18	1	Induced abortion
3	Advanced age, and NT:3.8 mm	47, XN, + 21	1	Induced abortion
4	Advanced age, NIPT suggests a high risk of trisomy 21	47, XN, + 21		Induced abortion
5	Advanced age, and NT:4.3 mm	47, XN, + 21	1	Induced abortion
6	Advanced age, B ultrasound suggests fetal persistence of the left upper lumen (type A), combined with the absence of the right superior vena cava (intrahepatic shunt type)	45, X	1	Induced abortion
7	Advanced age	46, X, inv(Y)(p11.2q11.23) pat	1	Continue to pregnancy
8	Advanced age	46, X, inv(Y)(p11q12) pat	1	Continue to pregnancy
9	Advanced age, interarm inversion of chromosome 7	46, XN, inv(7)(p13q36)pat	1	Continue to pregnancy
10	Advanced age, adverse pregnancy history	46, XN, t(8;17)(p11.2;q21.3)	1	Continue to pregnancy
11	Advanced age	46, XN, t(10;12)(q22;q22)	1	Continue to pregnancy
12	Advanced age	Mos47, XN, + 21[8]/46, XN[92]	1	Continue to pregnancy
13	Advanced age	46, XN, 15ph mat	1	Continue to pregnancy
14	Advanced age, adverse pregnancy history, assisted pregnancy	46, XN, 22ps + dn	1	Continue to pregnancy
15	Advanced age, pregnant woman with Robertsonian translocation 45, XN, rob (13; 14) (q10; q10)	45, XN, rob(13;14)(q10;q10) mat	1	Continue to pregnancy

CMA detects an exception procedure

CMA was performed in the amniotic fluid of 228 elderly pregnant women, among which 17 cases (7.46%) were abnormal. Among these 17 cases, 11 (11/17, 64.7%) were clearly pathogenic, and 6 cases (6/17,35.3%) were not clearly pathogenic. Among the 11 pathogenic cases, 2 were trisomy 18 syndrome (2/11, 18.2%), 3 were trisomy 21 syndrome (3/11, 27.3%), 1 was Turner syndrome (1/11, 9.0%), and 5 cases were microdeletion and microduplication syndrome (5/11, 45.5%) (Table 2).

Table 2

Abnormal pathogenicity of amniotic fluid CMA was detected in 17 elderly pregnant women (n = 17)
Sample number	Medical reasons	CMA	Interpretation of result	Cases	Pregnancy outcome
1	Advanced age, and NT:3.4 mm	arr(18)×3	trisomy 18 syndrome (clearly pathogenic)	1	Induced abortion
2	Advanced age, NIPT suggests a high risk of trisomy 18	arr(18)×3	trisomy 18 syndrome (clearly pathogenic)	1	Induced abortion
3	Advanced age, and NT:3.8 mm	arr(21)×3	trisomy 21 syndrome (clearly pathogenic)	1	Induced abortion
4	Advanced age, NIPT suggests a high risk of trisomy 21	arr(21)×3	trisomy 21 syndrome (clearly pathogenic)	1	Induced abortion
5	Advanced age, and NT:4.3 mm	arr(21)×3	trisomy 21 syndrome (clearly pathogenic)	1	Induced abortion
6	Advanced age, B ultrasound suggests fetal persistence of the left upper lumen (type A), combined with the absence of the right superior vena cava (intrahepatic shunt type)	arr(X)×1	Turner Syndrome (X monomer)	1	Induced abortion
7	Advanced age	arr(GRCh38)Xp22.31(6531712_8167604)×1	X-linked ichthyosis (clearly pathogenic, male onset)	1	Continue to pregnancy
8	Advanced age, a history of adverse pregnancy, and NT:4.0 mm	arr[GRCh38] 4q35.2(188469184_190036305)×1 17p12p11.2(14391113_16563998)×3	4q35.2 microdeletion 1.56 Mb (unclear significance) 17p12p11.2 Microrepeat 2.17 Mb (clearly pathogenic)	1	Induced abortion
9	Advanced age	arr[GRCh38] 15q11.2(22582283_23060000)×1	15q11.2 microdeletion 478 kb (clearly pathogenic)	1	induced labor
10	Advanced age, NIPT suggests a duplication of about 1.58 Mb in the short arm of fetal chromosome 17, p12 (14.08–15.66 Mb)	arr[GRCh38] 17p12(14182336_15510549)×3	17p12 microrepeat 1.32 Mb (clearly pathogenic)	1	induced labor
11	Advanced age	arr[GRCh38] 16p11.2(29568701_30165187)×3	16p11.2 Microrepeat 596 kb (clearly pathogenic)	1	induced labor
12	Advanced age, one of the twins, fertility history of chromosomal abnormalities	arr[GRCh38] Xp21.2p21.1(31427294_31614673)×0	Xp21.2p21.1 microdeletion 187 kb (unclear significance)	1	Continue to pregnancy
13	Advanced age	arr[GRCh38] 5p13.1p11(41104856_46313367)×2 hmz 15q11.2q14(22790831_36372186)×2 hmz 16p13.3p12.2(4365409_21338958)×2 hmz 17p13.2p12(4015812_13865600)×2 hmz	Genomic homozygous status (ROH) 45.61 Mb, increased risk of autosomal recessive disease (unclear significance)	1	induced labor
14	Advanced age	arr[GRCh38] 2p12(78388975_79768367) ×3	2p12 microduplication 1.37 Mb (unclear significance)	1	Continue to pregnancy
15	Advanced age, and NT:2.5 mm	arr[GRCh38] 15q21.2q21.3(52266935_53840624)×3	15q21.2q21.3 Microrepeat 1.57 Mb (unclear significance)	1	Continue to pregnancy
16	Advanced age	arr[GRCh38] 5p14.3(20100815_22867310) ×1	5p14.3 microdeletion 2.76 Mb (unclear significance)	1	Continue to pregnancy
17	Advanced age	arr[GRCh38] 11p15.5p15.3(230751_12977898)×2 hmz	Genome homozygous status 12.74 Mb (unclear significance)	1	Continue to pregnancy

Comparative analysis of chromosome karyotype abnormality and CMA detection results

Among 228 elderly pregnant women, 11 more abnormalities were detected in CMA than in chromosome karyotype in 213 patients with normal karyotype (nos. 7 to 17 in Table 3). Among them, five cases were clearly pathogenic, accounting for 45.5% (5/11). Compared with karyotype analysis, CMA increased the abnormal detection rate by 4.82%. Table 3 shows that the karyotype and CMA results of chromosomes 1–6 were abnormal, namely, trisomy 18, trisomy 21, and Turner syndrome, respectively. These chromosome number abnormalities were detected in both tests. Sample numbers 18–26 in Table 3 refers to the abnormality of chromosome inversion, translocation, chimerism, and polymorphism. Abnormalities were detected in all chromosome karyotypes, but not in CMA. As shown in Table 4, 15 cases had abnormal karyotype, and only 6 cases had abnormal CMA results. The coincidence rate of the abnormal detection rate of the two methods was 40% (Tables 3 and 4).

Table 3

Comparative analysis of chromosome karyotype and CMA detection results
Sample number	Medical reasons	Karyotype	CMA	Pregnancy outcome
1	Advanced age, and NT:3.4 mm	47, XN, + 18	Arr (18) 3 (clearly pathogenic)	Induced abortion
2	Advanced age, NIPT suggests a high risk of trisomy 18	47, XN, + 18	Arr (18) 3 (clearly pathogenic)	Induced abortion
3	Advanced age, and NT:3.8 mm	47, XN, + 21	Arr (21) 3 (clearly pathogenic)	Induced abortion
4	Advanced age, NIPT suggests a high risk of trisomy 21	47, XN, + 21	Arr (21) 3 (clearly pathogenic)	Induced abortion
5	Advanced age, and NT:4.3 mm	47, XN, + 21	Arr (21) 3 (clearly pathogenic)	Induced abortion
6	Advanced age, B ultrasound suggests fetal persistence of the left upper lumen (type A), combined with the absence of the right superior vena cava (intrahepatic shunt type)	45, X	Arr (X) 1 (X monomer)	Induced abortion
7	Advanced age	46, XN	arr(GRCh38)Xp22.31(6531712_8167604)×1	Continue to pregnancy
7	Advanced age	46, XN	(Clearly pathogenic, male onset)	Continue to pregnancy
8	Advanced age, a history of adverse pregnancy, and NT:4.0 mm	46, XN	Arr [GRCh38] 4q35.2 (188469184_190036305) 1 (unclear significance)	Induced abortion
8	Advanced age, a history of adverse pregnancy, and NT:4.0 mm	46, XN	17p12p11.2 (14391113_16563998) 3 (clear pathogenicity)	Induced abortion
9	Advanced age	46, XN	Arr [GRCh38] 15q11.2 (22582283_23060000) 1 (clearly pathogenic)	Induced labor
10	Advanced age, NIPT suggests a duplication of about 1.58 Mb in the short arm of fetal chromosome 17, p12(14.08–15.66 Mb)	46, XN	Arr [GRCh38] 17p12 (14182336_15510549) 3 (definite pathogenicity)	Induced labor
11	Advanced age	46, XN	Arr [GRCh38] 16p11.2 (29568701_30165187) 3 (clear pathogenicity)	Induced labor
12	Advanced age, one of the twins, fertility history of chromosomal abnormalities	46, XN	Arr [GRCh38] Xp21.2p21.1 (31427294_31614673) 0 (unclear meaning)	Continue to pregnancy
13	Advanced age	46, XN	arr[GRCh38] 5p13.1p11(41104856_46313367)×2 hmz	Induced labor
			15q11.2q14(22790831_36372186)×2 hmz
			16p13.3p12.2(4365409_21338958)×2 hmz
			17p13.2p12 (4015812_13865600) 2 hmz (ambiguous significance)
14	Advanced age	46, XN	Arr [GRCh38] 2p12 (78388975_79768367) 3 (ambiguous significance)	Continue to pregnancy
15	Advanced age, and NT:2.5 mm	46, XN	Arr [GRCh38] 15q21.2q21.3 (52266935_53840624) 3 (ambiguous significance)	Continue to pregnancy
16	Advanced age	46, XN	Arr [GRCh38] 5p14.3 (20100815_22867310) 1 (unclear significance)	Continue to pregnancy
17	Advanced age	46, XN	2 h for arr [GRCh38] 11p15.5p15.3 (230751_12977898) hmz (unclear significance)	Continue to pregnancy
18	Advanced age	46, X, inv(Y)(p11.2q11.23) pat	arr(1–22)×2, (X, N)×1	Continue to pregnancy
19	Advanced age	46, X, inv(Y)(p11q12) pat	arr(1–22)×2, (X, N)×1	Continue to pregnancy
20	Advanced age, interarm inversion of chromosome 7	46, XN, inv(7)(p13q36)pat	arr(1–22)×2, (X, N)×1	Continue to pregnancy
21	Advanced age, adverse pregnancy history	46, XN, t(8;17)(p11.2;q21.3)	arr(1–22)×2, (X, N)×1	Continue to pregnancy
22	Advanced age	46, XN, t(10;12)(q22;q22)	arr(1–22)×2, (X, N)×1	Continue to pregnancy
23	Advanced age	Mos47, XN, + 21[8]/46, XN[92]	arr(1–22)×2, (X, N)×1	Continue to pregnancy
24	Advanced age	46, XN, 15ph mat	arr(1–22)×2, (X, N)×1	Continue to pregnancy
25	Advanced age, adverse pregnancy history, assisted pregnancy	46, XN, 22ps + dn	arr(1–22)×2, (X, N)×1	Continue to pregnancy
26	Advanced age, pregnant woman with Robertsonian translocation 45, XN, rob (13; 14) (q10; q10)	45, XN, rob(13;14)(q10;q10) mat	arr(1–22)×2, (X, N)×1	Continue to pregnancy

Table 4

Comparison of chromosome karyotype analysis and CMA test results
Karyotype	CMA
Karyotype	Positive	Negative
Positive	6	9
Negative	11	202

Pregnant women aged 35 years or older are clinically defined as advanced pregnant women [6]. With increased age, the body function of women decline, as manifested by various indicators. Thus, the pregnancy risks and adverse pregnancy outcomes increase. According to a survey in China, the proportion of elderly pregnant women was 10.1% in 2011 [7] and increased to 20.5% in 2016 [8]. With the opening of the two- and three-child policy in this country, the number of elderly pregnant women is also increasing, causing a huge problem for the obstetrics and gynecology field.

Understanding and mastering the indications of amniocentesis is very important for prenatal doctors. However, at the chromosome level, only repeats and deletions larger than or equal to 10 Mb fragments can be seen. Small fragments are not easily observed by the naked eye. Its advantage is that chromosomal inversion and translocation can be seen. Therefore, we selected combined CMA detection technology [5] to detect the CNVs of human genome ≥ 400 kb and gene homozygous state (ROH) ≥ 10 Mb, and the probe covered 22 pairs of autosomes and sex chromosomes. This technique can effectively detect tiny deletions and repeats to observe the influence of microdeletions and repeats syndrome on the fetus, thereby playing a complementary role in chromosome karyotype results [9–10].

In the present study, amniotic fluid karyotype analysis and CMA detection were performed on 228 pregnant women in their 16–26 weeks (second trimester). Table 3 shows that 2 cases of trisomy 18 syndrome, 3 cases of trisomy 21 syndrome, and 1 case of Turner syndrome, as well as other aneuploidy abnormalities, were detected in chromosome karyotype and CMA detection. These results indicated that both were equally effective in large-fragment CNV detection. Among 228 elderly pregnant women, 15 cases had abnormal karyotype analysis, with a detection rate of 6.58%. Among them, 6 cases were induced labor (including 2 cases of trisomy 18, 3 cases of trisomy 21, and 1 case of Turner syndrome), accounting for 40% of the abnormal proportion (6/15). Han Juan et al. [11] believed that 5 out of 6 induced fetuses have trisomy 21 and trisomy 18, accounting for 83.3% (5/6). This finding indicates that abnormal trisomy syndrome such as Down syndrome and Edwards syndrome still account for the majority in elderly pregnant women, and advanced age increases the incidence of trisomy 21 and trisomy 18. This finding is similar to the results of this study on amniotic fluid in older pregnant women because advanced age increases the incidence of trisomy 21 and 18 syndrome. In Table 1, the serial number 12 was trisomy 21 chimera. This low proportion chimera was not detected in CMA, indicating that CMA was not sensitive to the low proportion chimera. Given that the pregnant woman refused to do further FISH verification, she insisted on continuing the pregnancy. The low proportion of trisomy 21 chimerism may be due to the presence of placental chimerism in the pregnant woman and the self-saving behavior of the fetus. These results indicated that CMA can detect only abnormalities with a high percentage of chimerism, and the ability of CMA to detect chromosomal chimerism was lower than that of karyotype analysis. In Table 3, serial numbers 18–20 were chromosomal inversion, serial numbers 21–22 and 26 were chromosomal translocation, serial number 23 was chromosomal chimera, and serial numbers 24–25 were chromosomal polymorphism. None of these chromosomal abnormalities was detected in CMA, indicating that G-banding karyotype analysis was more sensitive to chromosomal inversion, translocation, chimerism, and polymorphism [12]. Two cases of polymorphism and heterochromatin were detected by chromosome karyotype analysis. The chromosomal karyotypes of peripheral blood of most of these cases were analyzed, and results showed that most of these polymorphism changes and heterochromatin came from the parents of the fetus. As shown in Table 4, 15 cases had abnormal karyotype, and only 6 cases had abnormal CMA results. The coincidence rate of abnormal detection rate of the two methods was 40%. Therefore, karyotype analysis can provide more reasonable genetic counseling services in the case of chromosomal structural abnormalities, such as inversion, translocation, and chimerism.

In the cases numbered 7–17 in Table 3, CMA detected chromosome microdeletion and microduplication abnormalities, but no abnormalities were detected in karyotype analysis. This finding indicated that CMA had a higher sensitivity in detecting micro-CNVs. However, due to the improved sensitivity, Xie Qianqian et al. [13] studied chromosomes. They found that CMA can improve the detection rate of fetal chromosome copy-number abnormalities, consistent with the results of this study. Jin Qian [14] et al. studied the amniotic fluid chromosomes and found that CMA can reveal defects in chromosomes with abnormal balance-translocation results. It can also detect the deletion and repetition of small fragments relatively quickly, similar to this study. Panagiota Tzela et al. [10] studied 126 cases, including two groups. The first group had ultrasound soft markers (84 fetuses), and the second group had advanced maternal age (42 fetuses). The risk of CMA aberration is also considerable when ultrasound markers are found in late pregnancy or maternal age increases, consistent with the results of this study. Ching-Hua Hsiao et al. [15] evaluated the value of CMA in the prenatal diagnosis of high-risk pregnancies. After analyzing 178 chorionic villi and 859 amniocentesis amniotic fluid samples, they concluded that CMA is an effective first step in the prenatal diagnosis of high-risk pregnancies with fetal-structure abnormalities found in ultrasound or positive findings. This finding indicates the importance of the combined application of CMA and karyotype analysis, and the results are similar to those in the current study. Additionally, many CNVs of unknown clinical significance can be detected by CMA. As shown in Table 3, six cases with serial numbers 12–17 were detected with unclear diseases. The unclear pathogenicity increased the anxiety of the parents of the expectant fetus and the pressure of doctors' genetic counseling and prenatal diagnosis. It may even lead to wrong decisions. Chromosome karyotype analysis was performed in 228 elderly pregnant women, among which 213 were normal. There were 15 cases with abnormal karyotype and 6 cases with abnormal karyotype and CMA. Among 228 elderly pregnant women, 211 had normal CMA results and 17 had abnormal CMA results. A total of 32 abnormal cases were detected by chromosome karyotype analysis combined with CMA. The number of abnormalities increased compared with that of the two tests alone, indicating that the detection rate of abnormalities greatly improved after the joint test, and better data were provided for clinicians.

The above analysis showed that the two methods had advantages and disadvantages. Both can detect the abnormal number of chromosomes and the unbalanced rearrangement of large fragments. CMA can detect the tiny CNVs that karyotype analysis cannot detect, and chromosome karyotype analysis can detect chromosomal abnormalities including chromosomal translocation, inversion, and low proportion chimera that cannot be detected by CMA. Therefore, the two methods were complementary [16–17].

In summary, the karyotype analysis of union chromosome microarray CMA in older pregnant women can improve the detection rate of abnormal fetuses, especially the increased incidence of trisomy 21 and 18 syndrome [18]. Thus, clinicians should comprehensively analyze various related influencing factors, conduct reasonable clinical genetic counseling, provide complete information on the advantages and disadvantages of the method, and try to combine the two methods for reanalysis to improve the detection rate of chromosome abnormalities. Ultimately, missed diagnosis and misdiagnosis can be avoided, clinical diagnosis can be promoted, and birth defects in newborns can be reduced and prevented.

The above two methods had advantages and disadvantages. Karyotype analysis and microarray analysis technology can effectively improve the detection rate of abnormalities in the prenatal diagnosis of older pregnant women. Clinicians should comprehensively analyze various influencing factors, conduct reasonable genetic counseling, and combine the two methods of analysis to improve the detection rate of fetal abnormalities and prevent birth defects in newborns.

Financial Support: The authors gratefully acknowledge the financial support of the Project of Science and Technology Bureau of Pingxiang City, Jiangxi Province (2020PY118).

Declaration of Interest: All authors declare no potential conflicts of interest.

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No competing interests reported.

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Clinical application of chromosomal karyotype analysis combined with chromosomal microarray analysis in the prenatal diagnosis of pregnant women with advanced maternal age

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Abstract

Introduction

Materials And Methods

Subjects

Results

Chromosomal karyotype analysis detected abnormalities

CMA detects an exception procedure

Comparative analysis of chromosome karyotype abnormality and CMA detection results

Discussion

Conclusion

Declarations

References

Additional Declarations

Status:

Version 1