An overview of a 30-year experience with amniocentesis in a single tertiary medical center in Taiwan

Evaluation of chromosomal abnormalities in the postnatal cohort: A single-center study on 14,242 patients

BACKGROUND AND AIM

Chromosomal analysis is a laboratory technique used to examine the chromosomes of an individual, offering insights into chromosome numbers, structures, and arrangements to diagnose and comprehend genetic diseases. This retrospective study provides a comprehensive understanding of the distribution by indications in a large cohort of 14,242 patients and the frequency of chromosomal abnormalities in different clinical populations.

METHOD

The study examined various indications for karyotype evaluation, with recurrent pregnancy loss being the most common indication, followed by intellectual disability, dysmorphic features, congenital anomalies, and developmental delay.

RESULTS

The overall chromosomal abnormality rate was found to be 5.4%, with numerical abnormalities accounting for the majority of cases (61.7%). Trisomies, particularly trisomy 21, were the most frequent numerical abnormalities. In terms of structural abnormalities, inversions and translocations were the most commonly identified. The rates of chromosomal anomalies varied in specific indications such as amenorrhea, disorders of sex development, and Turner syndrome. The study also highlighted significant differences between males and females in the presence of chromosomal abnormalities across certain indications. Males exhibited a higher incidence of chromosomal abnormalities in cases of Down syndrome and infertility, whereas females showed higher abnormalities in terms of recurrent pregnancy loss.

CONCLUSION

While this study provides valuable insights into the frequency and distribution of chromosomal abnormalities, it has limitations, including its retrospective design and reliance on data from a single medical genetics department. Nevertheless, the findings emphasize the importance of karyotype analysis in diagnosing chromosomal disorders and providing appropriate management, while also pointing to potential gender-related variations in chromosomal abnormalities that warrant further investigation.

Frequency and clinical significance of chromosomal inversions prenatally diagnosed by second trimester amniocentesis

To compare the frequency and clinical significance of familial and de novo chromosomal inversions during prenatal diagnosis. This was a retrospective study of inversions diagnosed prenatally in an Asian population by applying conventional GTG-banding to amniocyte cultures. Data from 2005 to 2019 were extracted from a single-center laboratory database. The types, frequencies, and inheritance patterns of multiple inversions were analyzed. Pericentric variant inversions of chromosome 9 or Y were excluded. In total, 56 (0.27%) fetuses with inversions were identified in the 15-year database of 21,120 confirmative diagnostic procedures. Pericentric and paracentric inversions accounted for 62.5% (35/56) and 37.5% of the inversions, respectively. Familial inversions accounted for nearly 90% of cases, and de novo mutation was identified in two pericentric and two paracentric cases. Inversions were most frequently identified on chromosomes 1 and 2 (16.1% of all inversions), followed by chromosomes 6, 7, and 10 (8.9% of all cases). The indications for invasive testing were as follows: advanced maternal age (67.3%), abnormal ultrasound findings (2.1%), abnormal serum aneuploidy screening (20.4%), and other indications (10.2%). The mode of inheritance was available for 67.9% of cases (38/56), with 89.5% of inversions being inherited (34/38). A slight preponderance of inheritance in female fetuses was observed. Three patients with inherited inversions opted for termination (two had severe central nervous system lesions and one had thalassemia major). Gestation continued for 53 fetuses, who exhibited no structural defects at birth or significant developmental problems a year after birth. Our study indicates that approximately 90% of prenatally diagnosed inversions involve familial inheritance, are spreading, and behave like founder effect mutations in this isolated population on an island. This finding can help to alleviate anxiety during prenatal counseling, which further underscores the importance of parental chromosomal analysis, further genetic studies, and appropriate counseling in cases where a nonfamilial inversion is diagnosed.

Relation Between Increased Fetal Nuchal Translucency Thickness and Chromosomal Defects in Northern Vietnam

Objective To examine the prevalence of all chromosomal defects amongst fetuses with increased nuchal translucency thickness (NT). Methods This is a retrospective study amongst pregnant women indicated for amniocentesis by nuchal translucency above 3.0 mm and consent to the study. A total of 2,720 cases were recruited during the six-year period from 2015 to 2020. All singleton pregnancies were offered fetal karyotype when the fetal nuchal translucency was ≥2.5 mm. The prevalence of chromosomal defects was divided into five NT categories: 2.5-3.4 mm, 3.5-4.4 mm, 4.5-5.4 mm, 5.5-6.4 mm, ≥6.5 mm. Results The study identified 2,720 amniocentesis for increased NT. The mean maternal age was 29.19 (range 17-46) years, and the mean fetal crown-rump length was 66.9 (range 45-84) mm. The fetal karyotype was abnormal in 560 (20.6%) participants. The most frequent chromosomal disorders were trisomy 21 (55%), trisomy 18 (11.2%), trisomy 13 (3.9%), 45,XO (2.7%). The prevalence of chromosomal aberrations was ranged from 17.9% (NT between 2.5-3.4 mm) to 29.7% (NT≥6.5 mm). A majority of fetuses with trisomy 13, 18, or 21 has NT measurement lower than 5.5 mm. In those with Turner syndrome, there was no difference between the group with NT <5.5 mm and the group with NT ≥5.5 mm. Increased maternal age is a risk factor for chromosomal aberrations with the rate increased from 17.6% at the youngest maternal age of 30-34 to 34% at maternal age of 35-39 and to 50% at maternal age of ≥40. Conclusion In fetuses with increased NT, more than a half of the chromosomal abnormalities were affected by defects other than trisomy 21. The distribution of NT was different between Turner syndrome and trisomy 13, 18, 21 syndromes. Women aged 35 years or older had a higher risk of chromosomal aberrations.

5-Year review on amniocentesis and its maternal fetal complications

Background Amniocentesis is a well-known invasive procedure which is commonly carried out in the second trimester. The indication for amniocentesis varies throughout countries and centers. Despite providing significant prenatal diagnosis; many maternal and fetal complications have been reported from previous studies. Materials and methods This retrospective study aimed to determine the maternal and fetal complications following amniocentesis. This study involved all patients who underwent amniocentesis from January 2012 until June 2017 in a tertiary centre. Maternal age, parity, premorbid medical conditions, amniocentesis indications, gestational age during amniocentesis, karyotyping results, complications during and post procedure and the fetal outcomes were reviewed and analyzed. Results One hundred and fourteen patients' medical records were reviewed and the majority of patients (50.9%) ranged in age from age 30 to 39 years old with mean age of 34.29 years. Amniocentesis was performed during the second trimester in the majority of patients (71.1%). The indications for amniocentesis in this study were polyhydramnios (7.9%), advanced maternal age (9.6%), risk of Down's syndrome (31.6%), increased risk of Patau syndrome (6.1%), increased risk of Edward's syndrome (4.4%) and abnormal fetal ultrasonography (70.2%). Cytogenetics results of amniocentesis were normal in 82 patients (71.9%). The majority of patients (86.0%) had no complications. Two patients (12.5%) had intrauterine death presumed to be procedural related. Conclusion This 5-year retrospective study on amniocentesis procedure showed that the majority of amniocentesis were safe as 86.0% of the patients were free from any complications. Anticipating its complication is important as there is always a risk even though it is a safe procedure in general.

Prenatal diagnosis by chromosomal microarray analysis

Chromosomal microarray analysis (CMA) is performed either by array comparative genomic hybridization or by using a single nucleotide polymorphism array. In the prenatal setting, CMA is on par with traditional karyotyping for detection of major chromosomal imbalances such as aneuploidy and unbalanced rearrangements. CMA offers additional diagnostic benefits by revealing sub-microscopic imbalances or copy number variations that are too small to be seen on a standard G-banded chromosome preparation. These submicroscopic imbalances are also referred to as microdeletions and microduplications, particularly when they include specific genomic regions that are associated with clinical sequelae. Not all microdeletions/duplications are associated with adverse clinical phenotypes and in many cases, their presence is benign. In other cases, they are associated with a spectrum of clinical phenotypes that may range from benign to severe, while in some situations, the clinical significance may simply be unknown. These scenarios present a challenge for prenatal diagnosis, and genetic counseling prior to prenatal CMA greatly facilitates delivery of complex results. In prenatal diagnostic samples with a normal karyotype, chromosomal microarray will diagnose a clinically significant subchromosomal deletion or duplication in approximately 1% of structurally normal pregnancies and 6% with a structural anomaly. Pre-test counseling is also necessary to distinguish the primary differences between the benefits, limitations and diagnostic scope of CMA versus the powerful but limited screening nature of non-invasive prenatal diagnosis using cell-free fetal DNA.

Prenatal cytogenetic diagnosis in Taiwan: a nationwide population-based study

PURPOSE

The goal of this study was to gain a better understanding of the status of advanced maternal age among criteria for provision of amniocentesis in pregnant women in Taiwan.

MATERIALS AND METHOD

Data of 315 670 second-trimester amniocenteses from 28 national certified cytogenetics laboratories were retrospectively analyzed from the Prenatal Genetic Diagnosis Declaring and Database System of the Health Promotion Administration, Ministry of Health and Welfare in Taiwan between 2006 and 2013.

RESULTS

The number of pregnant women undergoing amniocentesis in Taiwan between 2006 and 2013 increased, and the most common three indications for amniocentesis were advance maternal age (75.11%), abnormal second trimester maternal serum screening (13.22%) and abnormal sonographic finding (8.00%). Down syndrome was the most common autosomal abnormality identified (25.74%); Turner syndrome was the most common sex chromosome abnormality (7.04%). Of structural rearrangements, 26.93% were balanced translocations and 17.10% were unbalanced translocations. The greatest proportion of fetal chromosomal abnormalities was found in cases where parents were also affected (38.02%).

CONCLUSIONS

Clinical workers should provide detailed genetic diagnostic information to pregnant women, especially those with the common amniocentesis indications, which will enable them to determine a birth plan.

Chromosomal Microarrays for the Prenatal Detection of Microdeletions and Microduplications

Chromosomal microarray analysis has replaced conventional G-banded karyotype in prenatal diagnosis as the first-tier test for the cytogenetic detection of copy number imbalances in fetuses with/without major structural abnormalities. This article reviews the basic technology of microarray; the value and clinical significance of the detection of microdeletions, microduplications, and other copy number variants; as well as the importance of genetic counseling for prenatal diagnosis. It also discusses the current status of noninvasive screening for some of these microdeletion and microduplication syndromes.

Analysis of chromosome 22q11 copy number variations by multiplex ligation-dependent probe amplification for prenatal diagnosis of congenital heart defect

BACKGROUND

Congenital heart defects (CHD) represent one of the most common birth defects. This study aimed to evaluate the value of multiplex ligation-dependent probe amplification (MLPA) as a tool to detect the copy number variations (CNVs) of 22q11 in fetuses with CHD.

RESULTS

A large cohort of 225 fetuses with CHD was screened by fetal echocardiography. Once common chromosome abnormalities in 30 fetuses were screened out by conventional G-banding analysis, the CNVs of chromosome 22q11 in the remaining 195 fetuses were determined by MLPA for prenatal genetic counseling. In 195 CHD fetuses with normal karyotype, 11 cases had pathological CNVs, including 22q11.2 deletion (seven cases), the deletion of 22q11 cat eye syndrome (CES) region (one case), 22q11.2 duplication (one case), 22q13.3 deletion (one case) and 17p13.3 deletion (one case). In total, our findings from MLPA screening represented 4.9 % in our cohort. Among these, three cases were inherited CNVs, and eight cases were de novo. These CNVs were further verified by single nucleotide polymorphism (SNP)-array analysis, and their chromosomal location was refined.

CONCLUSION

This study indicated that MLPA could serve as an effective test for routine prenatal diagnosis of 22q11 in fetuses with CHD.

Changes in and Efficacies of Indications for Invasive Prenatal Diagnosis of Cytogenomic Abnormalities: 13 Years of Experience in a Single Center

Background

Because the future application of cell-free fetal DNA screening is expected to dramatically improve the diagnostic yield and reduce unnecessary invasive procedures, it is time to summarize the indications of invasive prenatal diagnosis. This retrospective study was performed to evaluate the changes and efficacies of indications of invasive procedures for detecting cytogenomic abnormalities from 2000 to 2012.

Material/Methods

From our regional obstetric unit, 7818 invasive procedures were referred by indications of advance maternal age (AMA), abnormal ultrasound findings (aUS), abnormal maternal serum screening (aMSS), and family history (FH). Chromosome, fluorescence in situ hybridization (FISH), and array comparative genomic hybridization (aCGH) analyses were performed on chorionic villus sampling (CVS) and amniotic fluid (AF) specimens at the Yale Cytogenetics Laboratory. The abnormal findings from single or combined indications were compared to evaluate the diagnostic yield.

Results

The annual caseload declined by 57.2% but the diagnostic yield increased from 7.2% to 13.4%. Chromosomal and genomic abnormalities were detected in 752 cases (9.6%, 752/7818) and 12 cases (4%, 12/303), respectively. Significantly decreased AMA referrals and increased aUS and aMSS referrals were noted. The top 3 indications by diagnostic yield were AMA/aUS (51.4% for CVS, 24.2% for AF), aUS (34.7% for CVS, 14.5% for AF), and AMA/aMSS (17.8% for CVS, 9.9% for AF).

Conclusions

Over a period of 13 years, the indication of aMSS and aUS were increasing while AMA was decreasing for prenatal diagnosis of cytogenomic abnormalities, and there was a continuous trend of reduced invasive procedures. Prenatal evaluation using AMA/aUS was the most effective in detecting chromosomal abnormalities, but better indications for genomic abnormalities are needed.

Comprehensive treatment for infertile women with severe Asherman syndrome

OBJECTIVE

Many preoperative, intraoperative, and postoperative methods have been described that improve the outcomes of women with severe Asherman syndrome, and it is likely that an integrated application of all of these methods may provide better reproductive outcomes; however, there is as yet no report on this type of integrated approach.

MATERIALS AND METHODS

The cases of four infertile women with severe Asherman syndrome were analyzed retrospectively. The comprehensive therapeutic plan for the four women included (1) preoperative office hysteroscopy to confirm the diagnosis and evaluate the severity of disease; (2) the use of ultrasound-guided intraoperative abdominal procedures during the surgical procedure, including hysteroscopic adhesiolysis to ensure the entire the hysteroscopic dissection, and placement of a Hyalobarrier(®) gel and an intrauterine balloon catheter at the end of the surgery; (3) postoperative oral estrogen supplementation to enhance endometrial proliferation, removal of the balloon catheter, and a second-look office hysteroscopy; and (4) in vitro fertilization and embryo transfer (IVF & ET) for three of the four patients.

RESULT

After treatment, the endometrium was significantly thicker than at baseline (median endometrial thickness, 7.5 mm versus 3.0 mm, p < 0.05). All the women (100%, 4/4) conceived successfully (three undergoing IVF & ET, and one had a spontaneous pregnancy), but only two patients had a term pregnancy with cesarean section (one placenta previa and the other placental abruption), contributing to 50% of successful term pregnancies. One patient had the complication of abortion after amniocentesis. The last one woman underwent an abortion because of thyroid problems.

CONCLUSION

Comprehensive management offers promising reproductive outcomes for infertile women with severe Asherman syndrome.

Dilemmas in Prenatal Chromosomal Diagnosis Revealed Through a Single Center's 30 Years' Experience and 90,000 Cases

INTRODUCTION

The aim of this article is to provide a perspective of prenatal chromosomal diagnosis (PCD) derived from a single center's evolving experience from ∼90,000 consecutive prenatal cases and to highlight important issues and current dilemmas.

MATERIALS AND METHODS

Prenatal cases in this study (1985-2013) were referred for various indications, and PCD was performed by standard karyotype in 84,255 cases, multiplex ligation-dependent probe amplification (MLPA) panel in 3,010 cases and standalone array comparative genomic hybridization (aCGH) in 3,122 cases.

RESULTS

Classic karyotype revealed 1.7 and 7.9% of pathological cases in amniotic fluid and CVS samples, respectively, with common aneuploidies accounting for 59.6 and 64.3% of the total abnormal. Molecular approaches increased the diagnostic yield by 0.6% for MLPA and 1.6% for aCGH, uncovering pathogenic chromosomal abnormalities undetectable by karyotype analysis.

CONCLUSIONS

Current molecular diagnostic capabilities and the recent introduction of noninvasive prenatal testing (NIPT) point to one current major dilemma in PCD, with serious implications in genetic counseling, relating on the one hand to reaping the benefits from the high detection rate afforded through aCGH but accepting an invasive risk, and on the other hand, offering a lower detection rate practically only for Down syndrome, with minimal invasive risk.

Chromosomal deletions detected at amniocentesis

OBJECTIVE

The aim of this study is to present the incidence, prenatal and postnatal findings, and modes of ascertainment in chromosomal deletions detected at amniocentesis.

MATERIALS AND METHODS

We reviewed all the cases with chromosomal deletions, which were detected by amniocentesis in Mackay Memorial Hospital, Taipei, Taiwan, between January 1987 and December 2012. Data on the locations and types of deletion, reasons for performing amniocentesis, maternal age, gestational age at amniocentesis, fetal karyotypes, inheritance of deletions, and relative prenatal findings were collected.

RESULTS

Amniocentesis was performed in 33,305 cases within this period of time. Among these, 31 cases of chromosomal deletions were considered for the study. The mean gestational age at amniocentesis was 21.0 weeks (range from 15 weeks to 32 weeks) and the mean maternal age at amniocentesis was 32.1 years (range from 26 years to 37 years). Nineteen cases (61.3%) manifested fetal structural abnormalities on ultrasound, nine (29.0%) presented no ultrasound abnormalities, and three had an unknown status. The main modes of ascertainment included abnormal ultrasound findings in 10 cases (32.2%), advanced maternal age in 11 cases (35.5%), abnormal maternal serum screening results in six cases (19.6%), and other reasons in four cases (13.0%). Of the 27 cases with known inheritance, the deletion was inherited in two (6.6%) and de novo in 25 (92.6%). Males accounted for 11 (35.5%) and females for 20 (64.5%) cases. Chromosomal deletions are more often to occur in chromosomal 5(4 cases, 12.9%), chromosomal 18 (4 cases, 12.9%), chromosomal 4 (3 cases, 9.7%), chromosomal 7 (3 cases, 9.7%), chromosomal 10 (3 cases, 9.7%), chromosomal 11 (3 cases, 9.7%), and chromosomal 1 (2 cases, 6.5%). There were four cases of chromosomal mosaicism: two involved chromosome 5, one involved chromosome 10, and one involved chromosome 18. Twenty-three cases (74.2%) had terminal deletions and the other eight cases (26.7%) had interstitial-type deletions.

CONCLUSION

In summary, we have presented the results of prenatal diagnosis for chromosomal deletions using amniocentesis. Chromosomal deletions are more likely to occur in females and more often in chromosomal 5p and 18q. Prenatal diagnosis at amniocentesis is frequently associated with advanced maternal age, abnormal ultrasound findings, and abnormal maternal serum screening. The frequency of ascertainment in chromosome deletion seems to be directly correlated with advanced maternal age and abnormal ultrasound findings. In cases with terminal deletions, prenatal ultrasound plays a more important role for prenatal diagnosis.