Fetal Chromosome Research Articles

Comparative Study of Fluorescence in situ Hybridization Analysis and Karyotype Analysis in Spontaneous Abortion Etiology Diagnosis

Objective To compare the roles of fluorescence in situ hybridization (FISH) and karyotype analysis on chorionic villus in spontaneous abortion. Methods A total of 201 cases were included in this study and were randomly divided into 2 groups by the same gestational age. The villi from 100 cases (group A) were cultured and used for karyotype analysis, while the uncultured villi from 101 women (group B) were used for FISH. A case was randomly selected from pregnant patients of 6–11 weeks at each gestational week in each group, 6 cases from each group and a total of 12 cases were analyzed by FISH and karyotype at the same time. Results The successful karyotype analysis rate was 66.0%, and the abnormality karyotype rate was 30.3%; FISH success analysis rate was 100%, and the abnormality rate was 46.5%; there were significant differences between FISH and karyotype analysis (P=0.036). Conclusion There were obvious differences between the two techniques. FISH was more successfully analyzed, and was used to more precisely determine fetal chromosome number. It is an effective way to determine abnormal chromosome by integrating FISH and karyotype analysis in spontaneous abortion.

GW24-e3701 Echocardiographic Observation and Clinical Significance of Echogenic Intracardiac Foci in 310 Fetuses

ObjectivesTo assess the clinical meaning of Echogenic intracardiac focus in Fetuses by echocardiography. MethodsThe data of 310 fetuses diagnosed as Echogenic intracardiac focusby echocardiography were reviewed, the ultrasonic characters and...

Microarray-based prenatal diagnosis for the identification of fetal chromosome abnormalities

The goal of prenatal cytogenetic testing is to provide reassurance to the couple seeking testing for their pregnancy, identify chromosome abnormalities in the fetus, if present, and provide treatments and medical management for affected babies. Cytogenetic analysis of banded chromosomes has been the standard for identifying chromosome abnormalities in the fetus for over 40 years. With chromosome analysis, whole chromosome aneuploidies and large structural rearrangements can be identified. The sequencing of the human genome has provided the resources to develop molecular tools that allow higher resolution observations of human chromosomes. The future holds the promise of sequencing that may identify chromosomal imbalances and deleterious single nucleotide variants. This review will focus on the use of genomic microarrays for the testing and identification of chromosome anomalies in prenatal diagnosis and will discuss the future directions of fetal testing.

Application and evaluation of invasive prenatal diagnostic techniques and analysis of chromosomal karyotype

To evaluate the safety, effectiveness and complications of serial invasive prenatal diagnostic techniques, and to investigate the prenatal diagnosis indication as well as to analyze the abnormal chromosomal karyotype. We retrospectively studied all patients from March 2005 to May 2012 who received amniocentesis and cordocentesis in the prenatal diagnosis center of Second Xiangya Hospital. The indication of the procedure, successful rate and complications were evaluated, and 25 abnormal chromosome nuclear types were analyzed. A total of 669 patients received invasive prenatal diagnosis from March 2005 to May 2012 in Second Xiangya Hospital: 598 received amniocentesis and 71 cordocentesis carried out. Compared with the cordocentesis group, the amniocentesis group had higher achievement ratio (91.54% vs 100%, P<0.05), lower spontaneous abortion rate (1.41% vs 0.33%, P<0.05), fewer abnormal karyotypes (11.27% vs 2.84%, P<0.05) and lower expenditure (880 yuan vs 800 yuan, P<0.05). Positive screening, advanced maternal age, and ultrasonography abnormality were the top 3 indications of amniocentesis and cordocentesis. We found 25 abnormal karyotypes, including 6 cases of trisomy 21, 4 sex chromosomal abnormalities, 7 autosomal balanced translocations, 1 marker chromosome, and 7 mosaics. As a widely used invasive prenatal diagnosis, amniocentesis is safe and effective. The complications of cordocentesis are much higher than those of amniocentesis, which is not a proper routine procedure for prenatal diagnosis of abnormal karyotype. The analysis of karyotype not only can identify fetal chromosome abnormality, but also provide the scientific basis for pregnancy continuation, thus reducing the ratio of birth defect.

Prenatal diagnosis and molecular cytogenetic characterization of a de novo interstitial duplication of 14q (14q31.3→q32.12) associated with abnormal maternal serum biochemistry

ObjectiveTo present prenatal diagnosis and molecular cytogenetic characterization of a de novo interstitial duplication of 14q (14q31.3→q32.12) in a pregnancy associated with abnormal maternal serum biochemistry. Case ReportA 19-year-old woman underwent amniocentesis in the second trimester because of abnormal maternal serum biochemistry. Her husband was 33 years old. At 16 weeks of gestation, the levels of α-fetoprotein, unconjugated estriol, total β-human chorionic gonadotropin, and inhibin A were 0.8 multiples of median (MoM), 0.84 MoM, 3.06 MoM, and 1.14 MoM, respectively, consistent with a positive trisomy 21 risk of 1/269. Results of an amniocentesis revealed a small de novo interstitial duplication of 14q encompassing 14q31-q32.1. An array comparative genomic hybridization analysis detected a 6.6-Mb duplication at chromosome 14q31.3-q32.12. Results of a fluorescence in situ hybridization analysis showed a direct duplication of interstitial 14q. The karyotype was 46,XY,dup(14) (q31.3q32.12). Level II ultrasound was unremarkable. The parents decided to continue the pregnancy. A 3805-g healthy male baby was delivered at 39 weeks of gestation. When examined at 6 months of age, the neonate was normal in growth and psychomotor development with no apparent phenotypic abnormalities, although long-term follow-ups are required. ConclusionAbnormal maternal serum biochemistry in the second trimester may be a distinctive prenatal feature in pregnancy associated with fetal chromosome 14q duplication.

Prenatal diagnosis and molecular cytogenetic characterization of a de novo interstitial duplication of 11q (11q22.3→q23.3) associated with abnormal maternal serum biochemistry

ObjectiveTo present prenatal diagnosis and molecular cytogenetic characterization of a de novo interstitial duplication of 11q (11q22.3→q23.3) in a pregnancy associated with abnormal maternal serum biochemistry. Case ReportA 33-year-old woman underwent amniocentesis in the second trimester because of abnormal maternal serum biochemistry. Her husband was 33 years old. At 17 weeks of gestation, the levels of α-fetoprotein (AFP), unconjugated estriol (uE3), total β-human chorionic gonadotropin (β-hCG), and inhibin A were 0.65 multiples of median (MoM), 0.61 MoM, 0.32 MoM, and 0.55 MoM, respectively, consistent with a positive trisomy 18 risk of 1/128. Results of amniocentesis revealed a small de novo interstitial duplication of 11q encompassing 11q23. An array comparative genomic hybridization analysis detected a 9.04-Mb duplication at chromosome 11q22.3-q23.3. A polymorphic DNA marker analysis was carried out, which determined a paternal origin of the duplication. Results of fluorescence in situ hybridization analysis showed a direct duplication of interstitial 11q. The karyotype was 46,XX,dup(11)(q22.3q23.3). Level II ultrasound was unremarkable. The parents opted to continue the pregnancy. A 2792-g female baby was delivered at 38 weeks of gestation. When examined at 10 months of age, the neonate was small for age and was abnormal in psychomotor development with apparent facial dysmorphisms, and small hands and feet. ConclusionLow levels of AFP, uE3, β-hCG, and inhibin A in the second trimester maternal serum biochemistry may be a distinctive prenatal feature in pregnancy with fetal chromosome 11q duplication.

Noninvasive Prenatal Testing/Noninvasive Prenatal Diagnosis: the Position of the National Society of Genetic Counselors

The 1997 discovery of free fetal DNA in maternal plasma launched clinical researchers' efforts to establish a reliable method for non-invasive prenatal testing for fetal genetic conditions. Various methods, including, but not limited to, massively parallel sequencing (MPS) and selective analysis of cell-free fetal DNA in maternal plasma, have recently been developed as highly sensitive and specific noninvasive screening tools for common fetal chromosome aneuploidies. Incorporating these new noninvasive technologies into clinical practice will impact the current prenatal screening paradigm for fetal aneuploidy, in which genetic counseling plays an integral role. The National Society of Genetic Counselors (NSGC) currently supports Noninvasive Prenatal Testing/Noninvasive Prenatal Diagnosis (NIPT/NIPD) as an option for patients whose pregnancies are considered to be at an increased risk for certain chromosome abnormalities. NSGC urges that NIPT/NIPD only be offered in the context of informed consent, education, and counseling by a qualified provider, such as a certified genetic counselor. Patients whose NIPT/NIPD results are abnormal, or who have other factors suggestive of a chromosome abnormality, should receive genetic counseling and be given the option of standard confirmatory diagnostic testing.

Non‐invasive prenatal testing of fetal whole chromosome aneuploidy by massively parallel sequencing

To determine whether non-invasive prenatal testing by maternal plasma DNA sequencing can uncover all fetal chromosome aneuploidies in one simple sequencing event. Plasma samples from 435 pregnant women at high risk for Down syndrome were collected prior to amniocentesis in three hospitals in China between March 2009 and June 2011. We sequenced the plasma DNA extracted from these samples at low coverage. We discovered that the genome representation of each of the 24 chromosomes obeyed a linear relationship to its GC content. Applying this relationship, we analysed the copy number of each of the 24 chromosomes. Full fetal karyotyping was compared with maternal plasma DNA sequencing results. Among the 435 samples, 412 samples (94.7%) have full karyotyping and sequencing results. Sixty-seven samples containing a fetal chromosome aneuploidy, including trisomy 21, trisomy 18, trisomy 13, trisomy 9, monosomy X or others, can be accurately identified with a detection sensitivity of 100% and a detection specificity of 99.71%. Normalization of the chromosome representation values against chromosomal guanine/cytosine base content is the key issue to ensure the accuracy. Our results indicate that non-invasive detection of fetal chromosome aneuploidies for all 24 chromosomes in one single sequencing event is feasible.

Variables Influencing Pregnancy Termination Following Prenatal Diagnosis of Fetal Chromosome Abnormalities

The objective of this study was to identify variables that may influence the decision to terminate or continue a pregnancy affected by a chromosome abnormality. We performed a retrospective cohort analysis of 286 pregnancies diagnosed with a chromosome abnormality following genetic counseling and prenatal diagnosis. Data obtained included procedure type, chromosome results, ethnicity, maternal age, use of fertility treatments, and uptake of genetic counseling after results, among other factors. Wilcoxon rank sum test, Fisher's exact test, and univariate and multivariate logistic regression models were used for data analysis. The overall termination rate in this study was 82.9%. A lower likelihood to terminate was found in pregnancies with a diagnosis of a sex chromosome abnormality (OR 0.05, p < .0001), Filipina race (OR 0.10, p = .03), and uptake of second genetic counseling session (OR 0.05, p < .0001). Prior history of termination was associated with increased likelihood to terminate (OR 8.6, p = .02). Factors revealing no statistically significant association with termination included maternal age, gestational age, clinic site, fetal gender, ultrasound anomalies, reason for referral and who informed the patient. Our data affirm the complexity of the decision making process and reinforce that providers should refrain from making assumptions regarding a patient's likelihood to terminate based on factors such as maternal age, gestational age, type of procedure, or ultrasound.

Non-invasive prenatal testing for fetal aneuploidy by massively parallel DNA sequencing of maternal plasma: the future has arrived today/Nicht-invasiver Pränatal-Test auf fetale Aneuploidie mittels massiv-paralleler DNA-Sequenzanalyse im mütterlichen Plasma: in der Zukunft angekommen

Abstract After decades of research, non-invasive prenatal testing (NIPT) using maternal blood to determine fetal chromosome status has found its way from the research laboratory into clinical practice, triggering a long-awaited paradigm shift in prenatal care. A variety of methods using sequencing of maternal cell-free DNA (cfDNA) have now been studied, primarily demonstrating their ability to detect the most common fetal aneuploidy, trisomy 21 (T21). The focus of this article is on massively parallel sequencing (MPS) with optimized sequence tag mapping and chromosome quantification, which accurately detects T21 as well as multiple other aneuploidies across the genome. The power of this technique resides in its high precision and reduction of variation within and between sequencing runs. Using MPS, classification of aneuploidy status for a given sample can be reliably assigned from the genetic information alone without the need to factor in other maternal pre-test risk or other clinical variables. Performance of this method has been prospectively demonstrated in a rigorous, blinded, multi-center study in the United States. The findings suggest that MPS can be incorporated into existing prenatal screening algorithms to reduce unnecessary invasive procedures. This technology and key considerations for clinical implementation are discussed.

Significance of detecting free DNA from maternal plasma for the diagnosis of fetal chromosomal aneuploidies

To determine the feasibility and accuracy of detecting numerical chromosomal abnormalities by high-flux sequencing analysis of free fetal DNA from maternal plasma. High-flux sequencing was applied to analyze fetal chromosome sequence copy numbers in 153 pregnant women. Fetal karyotyping was also carried out on amniocentesis samples. Six cases were detected with fetal chromosomal abnormalities by high-flux sequencing analysis, among which five were confirmed by karyotyping to be chromosomal aneuploidies (47,XYY; 45,X; 47,XY,+18; 47,XY,+21 and 47,XY,+13), 1 case was confirmed to be structural rearrangement, i.e., 46,XY,der(13;21)(q10;q10),+21. Furthermore, 3 chromosomal polymorphisms (one 46,XY,21p+ and two 46,XY,Yqh-) were identified. The two methods yielded similar results on fetal chromosome copy number detection. High-flux sequencing analysis of free DNA derived from maternal plasma is efficient for detecting fetal chromosomal aneuploidies, and is non-invasive, highly sensitive and specific. It therefore has a broad application in antenatal diagnosis.

Investigation of the Frequencies of Prenatally Diagnosed Fetal Chromosomal Abnormalities at a Single Institution

The objective of this study was to investigate, retrospectively, the frequencies of fetal chromosomal abnormalities identified in 4176 prenatal cytogenetic examinations at the Xiamen Maternity and Child Health Care Hospital over the 5-year period from October 2005 to September 2010. The frequency of abnormal fetal karyotypes was 4.6%. Numerical chromosome abnormalities were identified in 150 cases. The frequency of trisomy 21 was by far the highest, followed by trisomy 18. Structural aberrations of chromosomes were identified in 43 cases, including 21 cases with balanced and 22 cases with unbalanced chromosomal aberrations. In addition, 16 cases of apparently de novo chromosomal aberrations and 27 cases of familial inheritances were observed. Increased awareness of the frequencies of fetal chromosome abnormalities is important for the improvement of prenatal care and providing the options of termination or continuation of the pregnancy. Data obtained in this study provide the basis of a database for genetic counseling.

Noninvasive prenatal diagnosis empowered by high‐throughput sequencing

Noninvasive prenatal diagnosis of fetal Down syndrome using direct nucleic acid analysis was once an elusive goal. The presence of cell-free fetal DNA in maternal plasma was discovered in 1997 and offered a new noninvasive source of fetal genetic material. A number of approaches have since been developed for the assessment of fetal chromosome dosage based on cellfree fetal DNA analysis. The most effective approach developed to date is based on massively parallel sequencing of maternal plasma DNA molecules for the detection of an increased representation of chromosome 21 DNA molecules in the plasma of women pregnant with trisomy 21 fetuses when compared with euploid pregnancies. A number of multicenter studies have since been conducted to evaluate the diagnostic efficacy of the sequencing-based method. To date, the literature contains results for the analysis of a total of 305 trisomy 21 pregnancies and 2061 euploid pregnancies. The overall diagnostic sensitivity and specificity were both 99%. Besides trisomy 21, massively parallel maternal plasma DNA sequencing has also been applied to the noninvasive detection of trisomy 18, trisomy 13 and fetal genetic sequences across the genome.

The Balance of the Immune System between T Cells and NK Cells in Miscarriage

Immunological dysfunction has been proposed to explain the etiology of recurrent pregnancy loss (RPL). The immunological environment differs between the decidua basalis and decidua parietalis, and also between RPL cases with normal fetal chromosomes and those with abnormal fetal chromosomes. The problem with analyzing decidual tissues from spontaneous abortions is that cause versus effect phenomena are difficult to distinguish. Recent data show that the immune system in a late-stage miscarriage is completely different from that in an early-stage miscarriage. If immunocompetent cells can cause RPL, the immunological environment may be a causative factor, especially in an early-stage miscarriage, at the decidua basalis, and/or in cases of RPL with a normal embryo. Careful examination of the immune system at the decidua basalis in an early-stage miscarriage in RPL cases with normal fetal chromosomes may reveal useful information. This paper aimed at finding a cause of RPL by analyzing the balance of the immune system between T cells and NK cells in an early-stage miscarriage.

Prenatal diagnosis of partial trisomy 3q resulting from t(3;14) in a fetus with multiple anomalies including vermian hypoplasia

While genetic origin of Dandy–Walker complex has not yet fully elucidated, the complex has been known to be associated with structural and chromosomal abnormalities. A partial trisomy 3q was also identified in patients with DWC.3q duplication syndrome is defined as duplications of large parts of 3q, especially 3q21-qter. Most cases with 3q duplication are diagnosed postnatally and the patients show typical features including various facial dysmorphisms, congenital heart defects, genitourinary malformations, and mental and growth retardation.Here we report a 28year old nulliparous woman who was referred from the infertility clinic at 21 gestational weeks. Fetal ultrasonographic examination showed various abnormal findings including a ventricular septal defect, hydrocephalus, and hypoplasia of the cerebellar vermis. Fetal chromosome analysis was initially reported as 46,XY,der(14)(?::p11.2→qter). Array CGH followed by FISH allowed precise characterization of the der(14) chromosome and the initial karyotype of the fetus had been changed to 46,XY,add(14)(p11).ish der(14)t(3;14)(q26.1;p11)(tel3q+).arr 3q26.1q29(166249469–199288361)x3.Though further studies are required, gene clusters rather than a single gene might be responsible for the clinical features of the Dandy–Walker complex.

Correlation between prenatal diagnosis by ultrasound and fetal autopsy findings in second‐trimester abortions

We evaluated the correlation between prenatal diagnosis by ultrasound and autopsy findings, based on 52 second-trimester pregnancies terminated due to fetal malformations or chromosome aberrations diagnosed at a gestational age of 12-25 weeks. In 24 pregnancies, there was full agreement between ultrasound and autopsy. In 23 fetuses, the main diagnosis was confirmed and additional or more specific findings were observed on autopsy. In five fetuses, there were considerable differences. Discrepancies between ultrasound and autopsy findings were mainly anomalies undetectable by ultrasound and thus expected; however, about one-third of the discrepancies were not expected, representing findings that were 'missed' at ultrasound. The main ultrasound diagnoses were confirmed in the majority of the pregnancies, but the additional information obtained at autopsy in more than half of the fetuses clearly shows the value and benefit of postmortem fetal examination following termination of a pregnancy.

Fetal akinesia deformation sequence: an etiology of fetal multiple joint contractures with poor prognosis

Objective To evaluate the diagnostic capability of prenatal ultrasound in diagnosis of fetal akinesia deformation sequence (FADS).Methods The prenatal sonographic characteristics of 5 fetuses with FADS were analyzed retrospectively.Results Both multiple joint contractures and central nervous system (CNS) anomalies,which include 5 small head circumferences,2 short cerebellar diameters,and 1 flat forehead,were found by prenatal ultrasound in all 5 FADS fetuses.Additional fetal abnormalities such as micrognathia,polyhydramnios,short umbilical cord and intrauterine growth retardation were also observed.The results of fetal chromosome analysis were available in 2 cases indicating normal karyotype.Conclusions Prenatal identification and diagnosis of FADS is possible based on the findings of sonographic examination. Key words: Ultrasonography, prenatal ; Abnormalities, multiple; Fetal akinesia deformation sequence

Non-invasive prenatal diagnosis of trisomy 21 by dosage ratio of fetal chromosome-specific epigenetic markers in maternal plasma

This study examined the methylation difference in AIRE and RASSF1A between maternal and placental DNA, and the implication of this difference in the identification of free fetal DNA in maternal plasma and in prenatal diagnosis of trisomy 21. Maternal plasma samples were collected from 388 singleton pregnancies, and placental or chorionic villus tissues from 112 of them. Methylation-specific PCR (MSP) and methylation-sensitive restriction enzyme digestion followed by fluorescent quantitative PCR (MSRE + PCR) were employed to detect the maternal-fetal methylation difference in AIRE and RASSF1A. Diagnosis of trisomy 21 was established according to the ratio of fetal-specific AIRE to RASSF1A in maternal plasma. Both methods confirmed that AIRE and RASSF1A were hypomethylated in maternal blood cells but hypermethylated in placental or chorionic villus tissues. Moreover, the differential methylation for each locus could be seen during the whole pregnant period. The positive rates of fetal AIRE and RASSF1A in maternal plasma were found to be 78.1% and 82.1% by MSP and 94.8% and 96.9% by MSRE + PCR. MSRE + PCR was superior to MSP in the identification of fetal-specific hypermethylated sequences (P<0.05). Based on the data from 266 euploidy pregnancies, the 95% reference interval of the fetal AIRE/RASSF1A ratio in maternal plasma was 0.33-1.77, which was taken as the reference value for determining the numbers of fetal chromosome 21 in 102 pregnancies. The accuracy rate in 98 euploidy pregnancies was 96.9% (95/98). Three of the four trisomy 21 pregnancies were confirmed with this method. It was concluded that hypermethylated AIRE and RASSF1A may serve as fetal-specific markers for the identification of fetal DNA in maternal plasma and may be used for noninvasive prenatal diagnosis of trisomy 21.

Detection and clinical significance of fetal specific mRNA from peripheral maternal blood

To investigate the methods and clinical significance of detecting PLAC4 and COL6A1 gene on fetal chromosome 21 from maternal peripheral blood. From Oct. 2008 to Nov. 2009 30 normal pregnancies in Weifang People's Hospital were selected as pregnant group, and 9 non-pregnant women were selected as control group. Quantitative real-time PCR was used to determine transcript levels of the target genes (PLAC4 and COL6A1) in blood samples. Correlation between the expression level and gestational age was analyzed. (1) PLAC4 mRNA was detected in peripheral blood of all pregnant women. Its maximum level was 12.760×10(3) copies/ml, whereas the minimum was 2.105×10(3) copies/ml, and the average value is 6.612×10(3) copies/ml. In control group the PLAC4 mRNA could not be detected. There was statistically significant difference (P < 0.01) between the two groups. (2) COL6A1 mRNA is detected in pregnant group and control group, and the concentration was 6.847×10(3) copies/ml and 7.322×10(3) copies/ml respectively, with no statistically significant difference (P > 0.05). (3) Correlation analysis: there was no relationship between the level of PLAC4, COL6A1 mRNA and the gestational age, the correlation coefficients (r) were 0.29 and 0.31, and the P values were 0.121 and 0.168 respectively. COL6A1 mRNA can be detected in both pregnant group and control group, so it is not specific for pregnancy. PLAC4 mRNA can be detected only in pregnant women, so it has specificity in pregnancy and can be a discriminative marker gene for prenatal diagnosis of trisomy 21 fetuses.

Patient desire for chromosome analysis of products of conception following miscarriage: a national survey

Most first trimester miscarriages are due to fetal chromosome abnormalities. Karyotype analysis of products of conception (POC) can provide useful information regarding cause of loss and identify patients who need additional testing or counseling. Despite this, chromosome testing of POC is not routinely done. The objective of our study was to evaluate patient interest in testing and the frequency with which testing is currently performed.