Chromosome abnormalities diagnosed in utero: a Japanese study of 28 983 amniotic fluid specimens collected before 22 weeks gestations

Is intermediate risk really intermediate? Comparison of karyotype and non-invasive prenatal testing results of pregnancies at intermediate risk of trisomy 21 on maternal serum screening

The purpose of this study was to assess the additional contribution of karyotyping compared with genome-wide non-invasive prenatal testing (NIPT) for pregnancies at intermediate risk for trisomy 21 (T21), calculated using the maternal serum screening without major structural anomalies detected through sonography. Karyotype results of all pregnancies undergoing invasive prenatal diagnostic testing between January 2013 and March 2022 were obtained from a large hospital-based laboratory. Pregnancies with no major structural anomalies on ultrasound (including soft markers) and an intermediate risk for T21 on maternal serum screening were included in this study. The additional contribution of karyotyping for abnormal karyotype results was calculated after excluding results that could theoretically be identified with genome-wide NIPT. Among the 511 pregnancies analyzed, 13 (2.54%) were found to have abnormal karyotype results, 9 (1.76%) of which could theoretically have been detected with genome-wide NIPT. Within the cohort, 6/263 (2.28%) of women aged 35 years and older, and 3/248 (1.20%) of women younger than 35 years had results that could have been detected with genome-wide NIPT. After excluding results detectable using genome-wide NIPT, the additional contribution of karyotyping was found as 4/502 (0.79%) for the entire cohort, 2/257 (0.77%) for women aged 35 years and older, 2/245 (0.81%) for women younger than 35 years. Of the 511 examined pregnancies at intermediate risk for T21 by maternal serum screening, genome-wide NIPT would have failed to detect 4 of 13 abnormal karyotype results. The findings hold importance in guiding couples' informed decision-making processes regarding their choice of genetic screening and diagnostic testing in case of intermediate risk for T21.

Maternal Exposure to Per- and Polyfluoroalkyl Substances and Offspring Chromosomal Abnormalities: The Japan Environment and Children's Study

BACKGROUND

Although recent in vitro experimental results have raised the question of whether maternal exposure to per- and polyfluoroalkyl substances (PFAS) may be a potential environmental risk factor for chromosomal abnormalities, epidemiological studies investigating these associations are lacking.

OBJECTIVES

This study examined whether prenatal PFAS exposure is associated with a higher prevalence of chromosomal abnormalities among offspring.

METHODS

We used data from the Japan Environment and Children's Study, a nationwide birth cohort study, and employed logistic regression models to examine the associations between maternal plasma PFAS concentrations in the first trimester and the diagnosis of chromosomal abnormalities in all births (artificial abortions, miscarriages, stillbirths, and live births) up to 2 years of age. In addition, we examined associations with mixtures of PFAS using multipollutant models.

RESULTS

The final sample consisted of 24,724 births with singleton pregnancies, of which 44 confirmed cases of chromosomal abnormalities were identified (prevalence: 17.8/10,000 births). When examined individually, exposure to perfluorononanoic acid (PFNA) and perfluorooctane sulfonic acid (PFOS) showed positive associations with any chromosomal abnormalities with age-adjusted odds ratios of 1.81 (95% CI: 1.26, 2.61) and 2.08 (95% CI: 1.41, 3.07) per doubling in concentration, respectively. These associations remained significant after Bonferroni correction, although they did not reach the adjusted significance threshold in certain sensitivity analyses. Furthermore, the doubling in all PFAS included as a mixture was associated with chromosomal abnormalities, indicating an age-adjusted odds ratio of 2.25 (95% CI: 1.34, 3.80), with PFOS as the predominant contributor, followed by PFNA, perfluoroundecanoic acid (PFUnA), and perfluorooctanoic acid (PFOA).

DISCUSSION

The study findings suggested a potential association between maternal exposure to PFAS, particularly PFOS, and chromosomal abnormalities in offspring. However, the results should be interpreted cautiously, because selection bias arising from the recruitment of women in early pregnancy may explain the associations. https://doi.org/10.1289/EHP13617.

Clinical utility of expanded non-invasive prenatal screening compared with chromosomal microarray analysis in over 8000 pregnancies without major structural anomaly

OBJECTIVES

To evaluate the theoretical added value of two types of non-invasive prenatal screening (NIPS) expansions in pregnancies without major structural anomalies over the commonly used NIPS for chromosomes 13, 18, 21, X and Y (5-NIPS) and to compare them with the added value of chromosomal microarray analysis (CMA).

METHODS

This was a retrospective cohort study based on CMA results of all pregnancies with normal ultrasound (including pregnancies with soft markers and with abnormal maternal serum screening) that had undergone amniocentesis between January 2013 to February 2022 and were registered in the database of the Rabin Medical Center genetic laboratory. We calculated the theoretical yield of 5-NIPS and compared the added value of expanded 5-NIPS for common microdeletions (1p36.3-1p36.2, 4p16.3-4p16.2, 5p15.3-5p15.1, 15q11.2-15q13.1 and 22q11.2) and genome-wide NIPS (including variants > 5 Mb) with the added value of CMA in the overall cohort and in subgroups according to indication for invasive testing.

RESULTS

Among the 8605 examined pregnancies, 122 (1.4%) clinically significant CMA results were demonstrated. Of these, 44 (36.1%) were theoretically detectable on 5-NIPS, with the rates of 1.56% in 642 pregnancies with abnormal maternal serum screening, 0.63% in 318 pregnancies with soft markers, 0.62% in 4378 women with advanced maternal age (≥ 35 years) and 0.15% in 3267 women younger than 35 years. In addition to aneuploidies detectable on 5-NIPS, three (0.03%) cases detectable on 5-NIPS expanded for common microdeletions and nine (0.10%) cases detectable on genome-wide NIPS (excluding common microdeletions) were identified in the overall cohort. The added value of expanded NIPS tools over 5-NIPS was significantly lower compared with that of CMA, for the overall cohort and subgroups.

CONCLUSIONS

5-NIPS and even genome-wide NIPS would miss 63.9% and 54.1% of clinically significant CMA findings, respectively. The added value of 5-NIPS expanded to detect common microdeletions over 5-NIPS is about 0.035%, and the overall added value of genome-wide NIPS aimed at large CNVs is about 0.14%, both much lower compared with the added value of CMA (0.91%). These findings should assist healthcare practitioners in guiding couples towards informed decision-making regarding the choice between prenatal invasive testing and NIPS. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Prevalence of common aneuploidy in twin pregnancies

The incidence of chromosomal abnormalities in twin pregnancies is not well-studied. In this retrospective study, we investigated the frequency of chromosomal abnormalities in twin pregnancies and compared the incidence of chromosomal abnormalities in dichorionic diamniotic (DD) and monochorionic diamniotic (MD) twins. We used data from 57 clinical facilities across Japan. Twin pregnancies of more than 12 weeks of gestation managed between January 2016 and December 2018 were included in the study. A total of 2899 and 1908 cases of DD and MD twins, respectively, were reported, and the incidence of chromosomal abnormalities in one or both fetuses was 0.9% (25/2899) and 0.2% (4/1908) in each group (p = 0.004). In this study, the most common chromosomal abnormality was trisomy 21 (51.7% [15/29]), followed by trisomy 18 (13.8% [4/29]) and trisomy 13 (6.9% [2/29]). The incidence of trisomy 21 in MD twins was lower than that in DD twins (0.05% vs. 0.5%, p = 0.007). Trisomy 21 was less common in MD twins, even when compared with the expected incidence in singletons (0.05% vs. 0.3%, RR 0.15 [95% CI 0.04–0.68]). The risk of chromosomal abnormality decreases in twin pregnancies, especially in MD twins.

Awareness of paternal age effect disorders among Japanese pregnant women: implications for prenatal genetic counseling for advanced paternal age

The increasing prevalence of advanced paternal age (APA) has mirrored the rise in maternal age. APA is associated with an increased risk of de novo pathogenic single-nucleotide variants, but this topic has been much less frequently discussed than advanced maternal age (AMA). To explore the awareness of pregnant women regarding paternal age effect (PAE) disorders, a self-administered questionnaire survey was conducted for pregnant women at their first prenatal visit before 17 weeks of gestation. A total of 120 valid respondents (95.2%) were included in the analyses. Of these, 63.3% of pregnant women were aware of PAE disorders. This was markedly lower than the 90.8% recognition of maternal age effect (MAE) disorders. One-third of women with awareness of MAE disorders were not aware of PAE disorders. Pregnant women who were parous, older than their male partners, with knowledge of prenatal testing prior to this pregnancy, and with experience of prenatal testing in a prior pregnancy were significantly more aware of PAE disorders than others. Awareness of PAE disorders was not associated with undergoing prenatal testing during the present pregnancy. Our results show that the prevalence of pregnant women's awareness of PAE disorders was lower than that of MAE disorders. The current study served as a preliminary baseline of information about pregnant women's awareness of PAE disorders. With the introduction of non-invasive prenatal testing, which has the potential to identify PAE disorders, these findings will help the development of a framework for comprehensive prenatal genetic counseling for APA pregnancies.

Attitude changes toward prenatal testing among women with twin pregnancies after the introduction of noninvasive prenatal testing: A single-center study in Japan

Aim

This study aimed to evaluate changes in prenatal testing among women with twin pregnancies before and after the introduction of noninvasive prenatal testing (NIPT). To date, no consensus on prenatal testing for twin pregnancies has been reached in Japan.

Methods

Women pregnant with twins who requested prenatal testing at Kyushu Medical Center from 2005 to 2018 were included in this study. Genetic counseling was provided to all participants. Their chosen methods of testing were collected and classified as invasive diagnosis (ID), noninvasive screening (NIS), and no test requested (NR). Parity, chorionicity, and methods of conception were assessed as attributes. The study period was divided into three terms according to testing availability in our center.

Results

After NIPT was introduced in our center, the use of ID methods decreased and eventually disappeared while NIS came to the forefront. NR was also the preferred choice of women with twin pregnancies before the introduction of NIPT and decreased but did not disappear after introducing NIPT. Women with twin pregnancies who underwent assisted reproduction initially showed hesitation to undergo testing but showed a strong preference for NIS after the introduction of NIPT. Differences in choice according to parity, chorionicity, and methods of conception were found before the introduction of NIPT but disappeared after introducing NIPT.

Conclusion

Increasing information about NIPT has apparently influenced the attitudes of women with twin pregnancies to prenatal testing in Japan. In particular, those who conceive through assisted reproductive technologies exhibited a strong preference for NIPT.

Trends of fetal chromosome analysis by amniocentesis before and after beginning of noninvasive prenatal testing: A single-center experience in Japan

AIM

This study is to investigate the role of amniocentesis for prenatal diagnosis before and after the beginning of noninvasive prenatal testing (NIPT) in Japan.

METHODS

We performed a retrospective analysis of genetic amniocentesis at mid-trimester (15-20 gestational weeks) for fetal karyotype analysis at Nagoya City University between April 2006 and March 2020. The indications, test results, and the detection rate of fetal abnormal karyotype were compared before (phase 1, P1) and after (phase 2, P2) beginning of NIPT at April 2013.

RESULTS

A total of 2458 (P1: 1132, P2: 1326) amniocentesis were enrolled in this study. The most frequent indication was advanced maternal age in both phases (P1: 78.2% %, P2: 81.1%). In P2, 110 patients (8.3%) received amniocentesis after positive or nonreportable NIPT results. Other indications were fetal abnormal findings by ultrasounds (P1: 15.4%, P2: 17.7%), abnormal maternal serum screening results (P1: 8.0%, P2: 10%), previous child with fetal chromosome aberration (P1: 6.5%, P2: 3.5%), and translocation of either partner (P1:1.5%, P2: 2.1%). The detection rate for fetal chromosomal aberrations including all indications was significantly increased in P2 (15.9%, 95% CI 14.0-18.0) as compared to P1 (9.0%, 7.4-10.8). However, if the indication was only advanced maternal age, the positive detection rate kept low in both phases (P1: 5.2%, 3.7-7.1, P2: 4.2%, 2.9-5.9).

CONCLUSION

Since the initiation of NIPT, the detection rate of fetal chromosomal abnormalities was higher in this study, suggesting that amniocentesis cannot be strongly recommended for advanced maternal age alone.

The correlation between maternal age and fetal sex chromosome aneuploidies: a 8-year single institution experience in China

Background

Although a few studies have investigated a possible association between maternal age and fetal sex chromosome aneuploidies (SCAs), most of these studies were limited to advanced maternal age (AMA) women and the results were conflicting. This study aimed to investigate the correlation between maternal age and common fetal SCAs (including 45,X, 47,XXY, 47,XXX and 47,XYY) in pregnant women of different ages that not only limited to AMA women. We retrospectively investigated a 8-year experience of prenatal diagnosis for fetal chromosome aberrations by second-trimester amniocentesis at a university teaching hospital in China. 20,409 amniotic fluid specimens collected at 19–22⁺⁶ gestational weeks were included in this study. The women were categorized into five age groups (≤ 23, 24–28, 29–33, 34–38, 39⁺ years) based on maternal age at the time of amniocentesis and entered as a categorical variable in all samples. The correlation between fetal SCAs and maternal age was determined using the logistic regression analysis. A chi-square test was performed to compare the incidence of fetal SCAs among age groups.

Results

A total of 179 cases of fetal SCAs were detected, and the incidence was 8.77‰ (about 1/114). The incidence of fetal SCAs increased significantly with advancing maternal age (SE, 0.014; odds ratio, 1.044; P = 0.002). Specifically, the incidence of 45,X (SE, 0.037; odds ratio, 0.916; P = 0.017) and 47,XXY (SE, 0.024; odds ratio, 1.127; P = 0.000) had significant correlation with maternal age, while the incidence of 47,XXX and 47,XYY had no correlation with maternal age (P = 0.473; P = 0.272, respectively). The incidence of fetal SCAs was also significantly different among age groups (χ² = 10.197, P = 0.037 < 0.05), from 5.81 per 1000 fetuses at the 24–28 years to 10.92 per 1000 at the 39⁺ years.

Conclusions

Maternal age was ascertained to be a strong risk factor for fetal SCAs.

Pregnant women's opinions toward prenatal pretest genetic counseling in Japan

In-person models of genetic counseling (GC) have been the common method in Japan for pregnant women to receive GC. However, recent increases in the number of pregnant women considering undergoing prenatal testing have made it challenging to retain individualized in-person care. To explore pregnant women’s opinions toward pretest GC models and the ideal time duration, a self-administered questionnaire survey was conducted for women at their first prenatal visit. A total of 114 valid respondents (93.4%) were included in the analyses. Of these, 80.7% of women preferred in-person GC, followed by classroom (9.6%), group (3.5%), and telegenetic-based GC (2.6%). Women with experience in undergoing prenatal testing significantly did not prefer in-person GC (p = 0.05). Sixty-two women (54.4%) preferred a duration of 15–29 min for pretest GC sessions, followed by 30–59 min (28.9%) and <15 min (14.9%). Women’s preference of ≥30 min in length was significantly associated with anhedonia, singleton pregnancies, acquaintance with people with trisomy 21, and awareness of prenatal testing. Women who were unaware of the need for agreement with the partner for prenatal testing and who did not know the average life expectancy of a trisomy 21 patient significantly preferred <15 min in length over other durations. While the majority of women preferred in-person GC for <30 min, their preferences varied by their background characteristics, experiences, attitudes, and knowledge. These findings will help establish a prenatal GC system offering a choice of GC models in Japan; however, further large-scale studies are needed to confirm these findings.

Equipoise of recent estimated Down syndrome live births in Japan

To support people with Down syndrome (DS), it is essential to know and predict the number of live births of children with this condition. In this study, we estimated DS live birth rates on the basis of maternal age distribution and numbers of births in the general population, the maternal-age specific chance for a live birth of a child with DS, and the prenatal diagnosis/termination rate. The total number of live births in Japan decreased to less than 1 million in 2016 and the percentage of women aged 35 years old or over giving birth has increased by sixfold. Prenatal genetic testing in Japan has gradually become more widespread, and 20% of all cases of DS were diagnosed prenatally in 2016. Meanwhile, the annual projected number of DS live births has remained steady at around 2,200 (22 per 10,000 births). In 2016, it was estimated that 70% of all DS babies were born to women of advanced maternal age (AMA). Given that Japan is facing a decreasing birth rate and an aging population, adoption of the practice of prenatal genetic testing for AMA has balanced the number of DS births over the last 7 years from 2010.

The outcomes of 31 cases of trisomy 13 diagnosed in utero with various management options

There are few reports on the prognosis of prenatally diagnosed trisomy 13 in relation to postnatal management. The aim of this study was to report on the prenatal and postnatal outcomes and postnatal management of trisomy 13 fetuses that were prenatally diagnosed at our center between 2003 and 2015. The data were retrospectively reviewed from medical records. Of the 31 cases of trisomy 13, 12 patients were diagnosed before 22 weeks of gestation, and 19 were diagnosed at or after 22 weeks of gestation. Nine families opted for termination of the pregnancy, 14 fetuses died, and 8 were born alive. Aggressive treatment was requested in two of the live births, with one patient achieving long-term survival (7 years). The other died during infancy (Day 61). One out of four who received palliative treatment is alive at two years of age with only nutrition supplementation. These three patients who achieved neonatal survival had few structural anomalies. Fetal death and early neonatal death are common in trisomy 13; however, fetuses that receive medical treatment for cases without major ultrasound abnormalities may achieve neonatal survival. Therefore, it is useful to provide comprehensive information, including precise ultrasound findings and treatment options, to parents with trisomy 13 fetuses during genetic counseling.