Prevalence of common aneuploidy in twin pregnancies

Significance of noninvasive prenatal testing using massively parallel sequencing in women with twin or vanishing twin pregnancies

Noninvasive prenatal testing diagnoses fetal aneuploidies in singleton pregnancies with trisomy 21, 18, or 13 accurately. However, clinical data on noninvasive prenatal testing in women with twin or vanishing twin pregnancies are limited. We report on the accuracy and prenatal and neonatal outcomes of noninvasive prenatal testing in twin and vanishing twin pregnancies. This retrospective study was conducted at 22 facilities belonging to the Noninvasive Prenatal Testing Consortium, part of a nationwide project in Japan, visited by women with twin or vanishing twin pregnancies between January 2015 and March 2022. This study investigated the accuracy and perinatal and neonatal outcomes of noninvasive prenatal testing using massively parallel sequencing in twin or vanishing twin pregnancies. Of 1013 women with twin pregnancies, 986 (97.3%) had negative; 13 (1.3%), positive; and 14 (1.4%), non-reportable noninvasive prenatal testing results. Of 225 women with vanishing twins, 203 (90.2%) had negative; 11 (4.9%), positive; and 11 (4.9%), non-reportable results. Among 1693 fetuses (77.3%) excluding 497 unknowns were available for follow-up, 1476 were from twin pregnancies, and 134 were from vanishing twin pregnancies, totaling 1610 babies has born. No false negatives were observed in the cases followed. These results indicate that noninvasive prenatal testing is useful for vanishing twin pregnancies and provide reassurance for pregnant women with twins and vanishing twins.

Diagnostic accuracy of cell-free fetal DNA in maternal blood in detecting chromosomal anomalies in twin pregnancy: systematic review and meta-analysis

OBJECTIVE

To report the diagnostic accuracy of cell-free fetal DNA (cfDNA) in maternal blood in detecting fetal chromosomal anomalies in twin pregnancy.

METHODS

PubMed, MEDLINE, EMBASE and Cochrane databases were searched from inception to November 2023. The inclusion criteria were twin pregnancy undergoing cfDNA screening for trisomies 21, 18 and 13, monosomy X and/or other sex-chromosome aneuploidies (SCA). The index test was cfDNA screening. The reference standard was pre- or postnatal karyotyping (in the case of a positive cfDNA result) or neonatal phenotypic assessment (in case of a negative cfDNA result). The quality of included studies was assessed using the revised quality assessment of diagnostic accuracy studies (QUADAS-2) tool. Summary estimates of diagnostic accuracy were computed using a bivariate random-effects model.

RESULTS

Thirty-five studies were included in the systematic review and meta-analysis. cfDNA had a high accuracy in detecting trisomy 21 in twin pregnancy, with a sensitivity of 98.8% (95% CI, 96.5-100%) and specificity of 100% (95% CI, 99.9-100%). Sensitivity and specificity were 94.9% (95% CI, 75.9-99.1%) and 100% (95% CI, 99.9-100%), respectively, for trisomy 18 and 84.6% (95% CI, 54.6-98.1%) and 100% (95% CI, 99.9-100%), respectively, for trisomy 13. We could not compute the diagnostic accuracy of cfDNA in detecting monosomy X, owing to an absence of positive cases, while cfDNA had a sensitivity of 100% (95% CI, 71.5-100%) and specificity of 99.8% (95% CI, 99.7-99.9%) for other SCA. The accuracy of cfDNA in detecting the common trisomies was similar in dichorionic and monochorionic twin pregnancies.

CONCLUSIONS

cfDNA has high diagnostic accuracy in detecting trisomies 21 and 18 in twin pregnancy, irrespective of chorionicity. Estimation of diagnostic accuracy for trisomy 13 and other SCA was limited by the small number of affected cases and the difficulty associated with detecting false-negative cases of other SCA, and thus requires confirmation in larger studies. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Noninvasive prenatal diagnosis (NIPD) of non-syndromic hearing loss (NSHL) for singleton and twin pregnancies in the first trimester

BACKGROUND

Noninvasive prenatal diagnosis (NIPD) has been proven feasible for non-syndromic hearing loss (NSHL) in singleton pregnancies. However, previous research is limited to the second trimester and the application in twin pregnancies is blank. Here we provide a novel algorithmic approach to assess singleton and twin pregnancies in the first trimester.

METHODS

A 324.614 kb capture panel was designed to selectively enrich target regions. Parental haplotypes were constructed by target sequencing of blood samples from the parents and the proband. Then single nucleotide polymorphisms (SNP) within target regions were classified into four and six categories in singleton and twin pregnancy, respectively. Combining relative haplotype dosage change (RHDO) and the Bayes factor (BF), fetal fraction (FF) and fetal genotype were deduced in singleton and twin pregnancies. The pregnant women's NIPD results were validated by invasive prenatal diagnosis and Sanger sequencing.

RESULTS

Sixteen women with singleton pregnancies and one woman with a twin pregnancy were recruited. Among the 16 singleton pregnancies, NIPD was successfully applied in 15 families and the coincidence rate with invasive prenatal diagnosis was 100% (15/15). Only one family NIPD result is "no call" because the imbalance distribution of SNP sites makes it difficult to estimate recombination events. Most (13/15) of pregnant women were diagnosed in the first trimester and the earliest gestation week was the 7th week. The twin pregnancy was a dichorionic diamniotic twin (DCDA). NIPD confirmed one fetus is affected, and another is a carrier with c.299_300delAT of GJB2 gene.

CONCLUSION

This study represents the pioneering evidence in the field, demonstrating the feasibility of NIPD for NSHL in twin pregnancies. Moreover, it provides a novel and advanced diagnostic approach for families at high risk of NSHL during pregnancy, offering earlier detection, enhanced safety, and improved accuracy.

A sociodemographic index identifies sex-related effects on insomnia in the Hispanic Community Health Study/Study of Latinos

Study Objectives

Sex differences are related to both biological factors and the gendered environment. We constructed measures to model sex-related differences beyond binary sex.

Methods

Data came from the baseline visit of the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). We applied the least absolute shrinkage and selection operator penalized logistic regression of male versus female sex over sociodemographic, acculturation, and psychological factors jointly. Two "gendered indices," the gendered index of sociodemographic environment (GISE) and gendered index of psychological and sociodemographic environment, summarizing the sociodemographic environment (GISE) and psychosocial and sociodemographic environment (GIPSE) associated with sex, were calculated by summing these variables, weighted by their regression coefficients. We examined the association of these indices with insomnia, a phenotype with strong sex differences, in sex-adjusted and sex-stratified analyses.

Results

The distribution of GISE and GIPSE differed by sex with higher values in male individuals. In an association model with insomnia, male sex was associated with a lower likelihood of insomnia (odds ratio [OR] = 0.60, 95% CI [0.53, 0.67]). Including GISE in the model, the association was slightly weaker (OR = 0.63, 95% CI [0.56, 0.70]), and weaker when including instead GIPSE in the association model (OR = 0.78, 95% CI [0.69, 0.88]). Higher values of GISE and of GIPSE, more common in the male sex, were associated with a lower likelihood of insomnia, in analyses adjusted for sex (per 1 standard deviation of the index, GISE OR = 0.92, 95% CI [0.87, 0.99], GIPSE OR = 0.65, 95% CI [0.61, 0.70]).

Conclusions

New measures such as GISE and GIPSE capture sex-related differences beyond binary sex and have the potential to better model and inform research studies of sleep health.

A sociodemographic index identifies non-biological sex-related effects on insomnia in the Hispanic Community Health Study/Study of Latinos

Background

Sex differences are related to both biological factors and the gendered environment. To untangle sex-related effects on health and disease it is important to model sex-related differences better.

Methods

Data came from the baseline visit of the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), a longitudinal cohort study following 16,415 individuals recruited at baseline from four study sites: Bronx NY, Miami FL, San Diego CA, and Chicago IL. We applied LASSO penalized logistic regression of male versus female sex over sociodemographic, acculturation, and psychological factors jointly. Two "gendered indices", GISE and GIPSE, summarizing the sociodemographic environment (GISE, primary) and psychosocial and sociodemographic environment (GIPSE, secondary) associated with sex, were calculated by summing these variables, weighted by their regression coefficients. We examined the association of these indices with insomnia derived from self-reported symptoms assessed via the Women Health Initiative Insomnia Rating Scale (WHIIRS), a phenotype with strong sex differences, in sex-adjusted and sex-stratified analyses. All analyses were adjusted for age, Hispanic/Latino background, and study center.

Results

The distribution of GISE and GIPSE differed by sex with higher values in male individuals, even when constructing and validating them on separate, independent, subsets of HCHS/SOL individuals. In an association model with insomnia, male sex was associated with lower likelihood of insomnia (odds ratio (OR)=0.60, 95% CI (0.53, 0.67)). Including GISE in the model, the association was slightly weaker (OR=0.63, 95% CI (0.56, 0.70)), and weaker when including instead GIPSE in the association model (OR=0.78, 95% CI (0.69, 0.88)). Higher values of GISE and of GIPSE, more common in male sex, were associated with lower likelihood of insomnia, in analyses adjusted for sex (per 1 standard deviation of the index, GISE OR= 0.92, 95% CI (0.87, 0.99), GIPSE OR=0.65, 95% CI (0.61, 0.70)).

Conclusions

New measures such as GISE and GIPSE capture sex-related differences beyond binary sex and have the potential to better model and inform research studies of health. However, such indices do not account for gender identity and may not well capture the environment experienced by intersex and non-binary persons.

Performance Evaluation of Noninvasive Prenatal Testing in Screening Chromosome Disorders: A Single-Center Observational Study of 15,304 Consecutive Cases in China

Objective

This study was to evaluate the performance of noninvasive prenatal testing (NIPT) in detecting fetal chromosome disorders in pregnant women.

Methods

From October 1st, 2017, to December 31th, 2022, a total of 15,304 plasma cell free DNA-NIPT samples were collected for fetal chromosome disorders screening. The results of NIPT were validated by confirmatory invasive testing or clinical outcome follow-up. Further, NIPT performance between low-risk and high-risk groups, as well as singleton pregnancy and twin pregnancy groups was compared. Besides, analysis of 111 false-positive cases was performed.

Results

Totally, NIPT was performed on 15,086 eligible venous blood samples, of which 179 (1.19%) showed positive NIPT results and 68 were further validated to be true positive samples via confirmatory invasive testing or follow-up of clinical outcomes. For common chromosome aneuploidies, sex chromosome abnormalities (SCA) and other chromosomal aneuploidies, the detection sensitivities of NIPT were all 100%, the specificities were 99.87%, 99.70%, and 99.68% and the positive predictive values (PPVs) were 65.45%, 31.82%, and 10.91%, respectively. No statistically significant variance in detection performance was observed among 2987 high-risk and 12,099 low-risk subjects, as well as singleton and twin pregnancy subjects. The concentration of cell-free fetal DNA of 111 false-positive cases ranged from 5.5% to 33.7%, which was higher than the minimum requirement of NIPT.

Conclusion

With stringent protocol, NIPT shows high sensitivity and specificity for detecting fetal chromosome disorders in a large-scale clinical service, helping improving overall pregnancy management.

Cell-free DNA screening for trisomy 21 in twin pregnancy: a large multicenter cohort study

BACKGROUND

Analysis of cell-free DNA from maternal blood provides effective screening for trisomy 21 in singleton pregnancies. Data on cell-free DNA screening in twin gestations are promising although limited. In previous twin studies, cell-free DNA screening was primarily performed in the second trimester and many studies did not report chorionicity.

OBJECTIVE

This study aimed to evaluate the screening performance of cell-free DNA for trisomy 21 in twin pregnancies in a large, diverse cohort. A secondary aim was to evaluate screening performance for trisomy 18 and trisomy 13.

STUDY DESIGN

This was a retrospective cohort study of twin pregnancies from 17 centers for which cell-free DNA screening was performed from December 2011 to February 2020 by one laboratory using massively parallel sequencing technology. Medical record review was conducted for all newborns and data on the birth outcome, the presence of any congenital abnormalities, phenotypic appearance at birth, and any chromosomal testing that was undertaken in the antenatal or postnatal period were extracted. Cases with a possible fetal chromosomal abnormality with no genetic test results were reviewed by a committee of maternal-fetal medicine geneticists. Cases with a vanishing twin and inadequate follow-up information were excluded. A minimum of 35 confirmed cases of trisomy 21 was required to capture a sensitivity of at least 90% with a prevalence of at least 1.9% with 80% power. Test characteristics were calculated for each outcome.

RESULTS

A total of 1764 samples were sent for twin cell-free DNA screening. Of those, 78 cases with a vanishing twin and 239 cases with inadequate follow-up were excluded, leaving a total of 1447 cases for inclusion in the analysis. The median maternal age was 35 years and the median gestational age at cell-free DNA testing was 12.3 weeks. In total, 81% of the twins were dichorionic. The median fetal fraction was 12.4%. Trisomy 21 was detected in 41 of 42 pregnancies, yielding a detection rate of 97.6% (95% confidence interval, 83.8-99.7). There was 1 false negative and no false positive cases. Trisomy 21 was detected in 38 out of 39 dichorionic twin pregnancies, yielding a detection rate of 97.4% (95% confidence interval, 82.6-99.7). Trisomy 18 was detected in 10 of the 10 affected pregnancies. There was 1 false positive case. Trisomy 13 was detected in 4 of the 5 cases, yielding a detection rate of 80% (95% confidence interval, 11.1-99.2). There was one false negative and no false positive cases. The nonreportable rate was low at 3.9 %.

CONCLUSION

Cell-free DNA testing is effective in screening for trisomy 21 in twin gestations from the first trimester of pregnancy. Detection of trisomy 21 was high in dichorionic and monochorionic twins, and the nonreportable result rates were low. This study included high numbers of cases of trisomy 18 and 13 when compared with the current literature. Although screening for these conditions in twins seems to be promising, the numbers were too small to make definitive conclusions regarding the screening efficacy for these conditions. It is possible that cell-free DNA testing performance may differ among laboratories and vary with screening methodologies.