Anxiety in Turner syndrome: Engaging community to address barriers and facilitators to diagnosis and care.

Turner syndrome (TS), caused by complete or partial loss of the second sex chromosome, is associated with complex medical manifestations. The TS community identifies anxiety as a major contributor to reduced quality of life. The study aimed to improve understanding of anxiety symptomatology, diagnosis, and care in individuals with TS. A mixed methods design integrated community engagement, including community leaders as co-investigators and a community advisory board, an online survey (N = 135), and in-depth interviews (N = 10). The majority of respondents reported that anxiety symptoms occur two or more days per week, with self-advocates reporting more frequent symptoms than caregivers (p = 0.03). Self-advocates reported feeling anxious more often at school/work; both rater groups reported anxiety-related behaviors were most likely to be expressed at home. Insomnia was the most common symptom of anxiety endorsed across age and rater groups (>70%). Anxiety symptoms and triggers changed with age and often were undiagnosed or untreated during childhood. Therapy and medication were reported as helpful by most respondents who had tried these strategies. Qualitative themes included: 'Triggers for anxiety are related to TS', 'Anxiety impacts the whole family', and 'Opportunities for early identification and intervention'.

Vertical cephalometric characteristics in different populations with Turner syndrome as compared to non-syndromic populations: A meta-analysis.

AIMS: The present aim was to evaluate vertical cephalometric characteristics in populations with Turner syndrome (TS) using meta-analysis methodology. METHODS: Six electronic databases were queried, up to August 2023, to identify studies comparing the vertical cephalometric characteristics in populations with TS, compared to female control groups. Data were extracted from eligible studies and random-effects meta-analysis was employed. Subgroup meta-analyses for age and karyotype were also attempted. Risk of bias was assessed using a modified version of the AXIS tool. RESULTS: From the initial 195 studies identified, 17 were included in the quantitative synthesis, resulting in a sample of 417 patients with TS, originating from 10 different countries. Risk of bias was overall questionable. Mandibular ramus height was found to be smaller in females with TS, along with a reduction in posterior facial height, a larger anterior-posterior facial height ratio, and an increase in the mandibular plane angle. Subgroup meta-analyses showed that females with the monosomy X karyotype had vertical cephalometric characteristics which deviated more from the norm than those with other karyotypes. CONCLUSION: The vertical lateral cephalometric characteristics of females with TS differ significantly from those of non-syndromic females, with the largest and most consistent deviation being seen in the monosomy X karyotype. Females with TS show less craniofacial posterior vertical development, with an evident reduction in mandibular ramus height leading to the cephalometric characteristics observed.

Relationships among maternal monosomy X mosaicism, maternal trisomy, and discordant sex chromosome aneuploidies.

OBJECTIVE: To explore the impact of maternal factors on the false-positive fetal sex chromosome aneuploidies (SCAs) results obtained through noninvasive prenatal screening (NIPS). METHODS: We retrospectively analyzed pregnant women with high-risk SCAs as revealed using NIPS between January 2017 and December 2022. Clinical data such as results of invasive prenatal diagnoses, copy number variation sequencing (CNV-seq) and pregnancy outcomes were analysed. RESULTS: Overall, 177 (0.6 %) women with SCA-positive results were collected from 27,941 patients who had undergone NIPS. Among them, 110 (62.2 %) pregnant women chose prenatal diagnosis and 39 (35.5 %) cases were confirmed. For the women with monosomy X false-positive results from the NIPS, 53.1 % (17/32) were found to be maternal mosaicism monosomy X. In cases with 47, XXX false-positive results, 60 % (6/10) of them were maternal 47,XXX (5 cases) or maternal mosaicism 47,XXX (1 case). One (1/6, 16.7 %) case of maternal mosaicism monosomy X was detected in the false positive results of 47, XXY/47, XYY revealed. The incidence rate of maternal sex chromosome abnormalities was positively correlated with the Z-score of ChrX. When the Z-score of ChrX ≥ 15, more than 50 % of pregnant women were found to be maternal sex chromosome abnormalities, and when Z-score ≥ 30, the incidence rate was as high as 100 %. CONCLUSIONS: Maternal monosomy X mosaicism and trisomy X respectively played an important role in the discordance of 45, X and 47, XXX revealed by NIPS. CNV-seq was recommended for the pregnant women at risk of maternal sex chromosome abnormalities, which could help clinicians to provide more accurate and efficient advice during genetic counseling and to guide appropriate prenatal diagnosis strategy for the next pregnancy.

Inspiring New Science to Guide Healthcare in Turner Syndrome: Rationale, design, and methods for the InsighTS Registry.

Inspiring New Science to Guide Healthcare in Turner Syndrome (InsighTS) Registry is a national, multicenter registry for individuals with Turner syndrome (TS) designed to collect and store validated longitudinal clinical data from a diverse cohort of patients with TS. Herein, we describe the rationale, design, and approach used to develop the InsighTS registry, as well as the demographics of the initial participants to illustrate the registry's diversity and future utility. Multiple stakeholder groups have been involved from project conceptualization through dissemination, ensuring the registry serves the priorities of the TS community. Key features of InsighTS include recruitment strategies to facilitate enrollment of participants that appropriately reflect the population of individuals with TS receiving care in the US, clarity of data ownership and sharing, and sustainability of this resource. The registry gathers clinical data on diagnosis, treatment, comorbidities, health care utilization, clinical practices, and quality of life with the goal of improving health outcomes for this population. Future directions include multiple patient-centered clinical-translational research projects that will use the InsighTS platform. This thorough and thoughtful planning will ensure InsighTS is a valuable and sustainable resource for the TS community for decades to come.

Case report: Prenatal diagnosis of rare chromosome mosaicism: discordant results between chorionic villi and amniotic fluid samples.

Objective: We described a unique case of near-negative chromosome mosaicism in chorionic villi but complete monosomy X in amniotic fluid. Methods: Chorionic villus sampling and amniocentesis were performed separately in the first and second trimesters. Chromosomal microarray (CMA) and rapid aneuploidy detection (QF-PCR and FISH) were performed on placental villi and uncultured amniotic fluid. After pregnancy termination, the placenta, umbilical cord, and fetal muscle tissues were sampled for FISH detection. Results: The CMA revealed a lower signal from chromosome X in chorionic villi, with a copy number of 1.85, implying the presence of mosaic monosomy X. However, the QF-PCR and FISH results were nearly normal. In uncultured amniotic fluid, CMA and rapid aneuploidy detection indicated complete monosomy X. Across different sampling points on the aborted fetus, the FISH results varied from normal, to mosaic, and then complete monosomy X. Conclusion: This case presents a rare and complex situation where sampling from uncultured chorionic villi indicated low-level chromosome mosaicism, while sampling from amniotic fluid revealed complete monosomy X. Although some of these discordant outcomes may be due to methodological limitations, we conclude that prenatal consultation should be combined with fetal ultrasound phenotype and genetic testing for a comprehensive evaluation of fetal genetic abnormalities.

Performance of prenatal cfDNA screening for sex chromosomes.

PURPOSE: The aim of this study was to assess the performance of cell-free DNA (cfDNA) screening to detect sex chromosome aneuploidies (SCAs) in an unselected obstetrical population with genetic confirmation. METHODS: This was a planned secondary analysis of the multicenter, prospective SNP-based Microdeletion and Aneuploidy RegisTry (SMART) study. Patients receiving cfDNA results for autosomal aneuploidies and who had confirmatory genetic results for the relevant sex chromosomal aneuploidies were included. Screening performance for SCAs, including monosomy X (MX) and the sex chromosome trisomies (SCT: 47,XXX; 47,XXY; 47,XYY) was determined. Fetal sex concordance between cfDNA and genetic screening was also evaluated in euploid pregnancies. RESULTS: A total of 17,538 cases met inclusion criteria. Performance of cfDNA for MX, SCTs, and fetal sex was determined in 17,297, 10,333, and 14,486 pregnancies, respectively. Sensitivity, specificity, and positive predictive value (PPV) of cfDNA were 83.3%, 99.9%, and 22.7% for MX and 70.4%, 99.9%, and 82.6%, respectively, for the combined SCTs. The accuracy of fetal sex prediction by cfDNA was 100%. CONCLUSION: Screening performance of cfDNA for SCAs is comparable to that reported in other studies. The PPV for the SCTs was similar to the autosomal trisomies, whereas the PPV for MX was substantially lower. No discordance in fetal sex was observed between cfDNA and postnatal genetic screening in euploid pregnancies. These data will assist interpretation and counseling for cfDNA results for sex chromosomes.

Neuropsychological and mental health concerns in a multicenter clinical sample of youth with turner syndrome.

Clinical practice guidelines for individuals with Turner syndrome (TS) recommend screening for neuropsychological concerns (NC) and mental health concerns (MHC). However, current provider screening and referral patterns for NC and MHC are not well characterized. Additionally, prevalence of and risk factors for NC and MHC vary across studies. This multicenter chart review study examined the prevalence, risk factors for, and management of NC and MHC in a cohort of 631 patients with TS from three pediatric academic medical centers. NC and/or MHC were documented for 48.2% of patients. Neuropsychological evaluation recommendations were documented for 33.9% of patients; 65.4% of the sample subsequently completed these evaluations. Mental health care recommendations were documented in 35.0% of records; subsequent documentation indicated that 69.7% of these patients received such services. Most notably, rates of documented MHC, NC, and related referrals differed significantly by site, suggesting the need for standardized screening and referral practices. TS diagnosis in early childhood was associated with an increased risk of NC. Spontaneous menarche was associated with increased risk of MHC. Younger age at growth hormone initiation was associated with both increased risk of isolated NC and co-occurring NC and MHC. Mosaic karyotype was associated with decreased risk of NC and MHC.

Monosomy X in isogenic human iPSC-derived trophoblast model impacts expression modules preserved in human placenta.

Mammalian sex chromosomes encode homologous X/Y gene pairs that were retained on the Y chromosome in males and escape X chromosome inactivation (XCI) in females. Inferred to reflect X/Y pair dosage sensitivity, monosomy X is a leading cause of miscarriage in humans with near full penetrance. This phenotype is shared with many other mammals but not the mouse, which offers sophisticated genetic tools to generate sex chromosomal aneuploidy but also tolerates its developmental impact. To address this critical gap, we generated X-monosomic human induced pluripotent stem cells (hiPSCs) alongside otherwise isogenic euploid controls from male and female mosaic samples. Phased genomic variants in these hiPSC panels enable systematic investigation of X/Y dosage-sensitive features using in vitro models of human development. Here, we demonstrate the utility of these validated hiPSC lines to test how X/Y-linked gene dosage impacts a widely used model for human syncytiotrophoblast development. While these isogenic panels trigger a GATA2/3- and TFAP2A/C-driven trophoblast gene circuit irrespective of karyotype, differential expression implicates monosomy X in altered levels of placental genes and in secretion of placental growth factor (PlGF) and human chorionic gonadotropin (hCG). Remarkably, weighted gene coexpression network modules that significantly reflect these changes are also preserved in first-trimester chorionic villi and term placenta. Our results suggest monosomy X may skew trophoblast cell type composition and function, and that the combined haploinsufficiency of the pseudoautosomal region likely plays a key role in these changes.

Is Fetal Hydrops in Turner Syndrome a Risk Factor for the Development of Maternal Mirror Syndrome?

Mirror syndrome is a rare and serious maternal condition associated with immune and non-immune fetal hydrops after 16 weeks of gestational age. Subjacent conditions associated with fetal hydrops may carry different risks for Mirror syndrome. Fetuses with Turner syndrome are frequently found to be hydropic on ultrasound. We designed a retrospective multicenter study to evaluate the risk for Mirror syndrome among pregnancies complicated with Turner syndrome and fetal hydrops. Data were extracted from a questionnaire sent to specialists in maternal fetal medicine in Germany. Out of 758 cases, 138 fulfilled our inclusion criteria and were included in the analysis. Of the included 138, 66 presented with persisting hydrops at or after 16 weeks. The frequency of placental hydrops/placentomegaly was rather low (8.1%). Of note, no Mirror syndrome was observed in our study cohort. We propose that the risk of this pregnancy complication varies according to the subjacent cause of fetal hydrops. In Turner syndrome, the risk for Mirror syndrome is lower than that reported in the literature. Our observations are relevant for clinical management and parental counseling.

Cell-free DNA screening positive for monosomy X: clinical evaluation and management of suspected maternal or fetal Turner syndrome.

Initially provided as an alternative to evaluation of serum analytes and nuchal translucency for the assessment of pregnancies at high risk of trisomy 21, cell-free DNA screening for fetal aneuploidy, also referred to as noninvasive prenatal screening, can now also screen for fetal sex chromosome anomalies such as monosomy X as early as 9 to 10 weeks of gestation. Early identification of Turner syndrome, a sex chromosome anomaly resulting from the complete or partial absence of the second X chromosome, allows medical interventions such as optimizing obstetrical outcomes, hormone replacement therapy, fertility preservation and support, and improved neurocognitive outcomes. However, cell-free DNA screening for sex chromosome anomalies and monosomy X in particular is associated with high false-positive rates and low positive predictive value. A cell-free DNA result positive for monosomy X may represent fetal Turner syndrome, maternal Turner syndrome, or confined placental mosaicism. A positive screen for monosomy X with discordant results of diagnostic fetal karyotype presents unique interpretation and management challenges because of potential implications for previously unrecognized maternal Turner syndrome. The current international consensus clinical practice guidelines for the care of individuals with Turner syndrome throughout the lifespan do not specifically address management of individuals with a cell-free DNA screen positive for monosomy X. This study aimed to provide context and expert-driven recommendations for maternal and/or fetal evaluation and management when cell-free DNA screening is positive for monosomy X. We highlight unique challenges of cell-free DNA screening that is incidentally positive for monosomy X, present recommendations for determining if the result is a true-positive, and discuss when diagnosis of Turner syndrome is applicable to the fetus vs the mother. Whereas we defer the subsequent management of confirmed Turner syndrome to the clinical practice guidelines, we highlight unique considerations for individuals initially identified through cell-free DNA screening.

DNA Methylation Analysis of Turner Syndrome BAV.

Turner Syndrome (TS) is a rare cytogenetic disorder caused by the complete loss or structural variation of the second sex chromosome. The most common cause of early mortality in TS results from a high incidence of left-sided congenital heart defects, including bicuspid aortic valve (BAV), which occurs in about 30% of individuals with TS. BAV is also the most common congenital heart defect in the general population with a prevalence of 0.5-2%, with males being three-times more likely to have a BAV than females. TS is associated with genome-wide hypomethylation when compared to karyotypically normal males and females. Alterations in DNA methylation in primary aortic tissue are associated with BAV in euploid individuals. Here we show significant differences in DNA methylation patterns associated with BAV in TS found in peripheral blood by comparing TS BAV (n = 12), TS TAV (n = 13), and non-syndromic BAV (n = 6). When comparing TS with BAV to TS with no heart defects we identified a differentially methylated region encompassing the BAV-associated gene MYRF, and enrichment for binding sites of two known transcription factor contributors to BAV. When comparing TS with BAV to euploid women with BAV, we found significant overlapping enrichment for ChIP-seq transcription factor targets including genes in the NOTCH1 pathway, known for involvement in the etiology of non-syndromic BAV, and other genes that are essential regulators of heart valve development. Overall, these findings suggest that altered DNA methylation affecting key aortic valve development genes contributes to the greatly increased risk for BAV in TS.

Incidental Detection of a Chromosomal Aberration by Array-CGH in an Early Prenatal Diagnosis for Monogenic Disease on Coelomic Fluid.

BACKGROUND: Turner syndrome is a rare genetic condition in which a female is partly or completely missing an X chromosome. Signs and symptoms vary among those affected. In fetuses that survive at birth and without congenital malformations, the prognosis is usually positive, but it has high lethality in utero, especially in the first trimester of pregnancy. METHODS: We report a case of monosomy X detected during a prenatal diagnosis for beta thalassemia on coelomic fluid (CF) at the VIII week of gestation. Beta globin gene analysis, whole genome amplification (WGA), quantitative fluorescent PCR and array comparative genomic hybridization (array-CGH) were performed on DNA extracted from CF. RESULTS: A monoallelic pattern of all Short Tandem Repeats mapped on the X chromosome was found and array-CGH performed on WGA from a few fetal erythroblasts confirmed monosomy X. CONCLUSION: This report underlines the importance of an early prenatal diagnosis and the countless potentialities of array-CGH that could make definition of molecular karyotype possible from a few fetal cells, unlike conventional cytogenetic techniques that require a greater cellular content. This is the first report of a molecular karyotype obtained from two cells selected by micromanipulation of CF and defined at such an early gestational age.

Searching chromosome mosaicisms in 45, X Turner syndrome: how relevant is it?

ABSTRACT Objective: To investigate the presence of chromosome mosaicism, especially for the presence of Y derived material in 45,X women with Turner syndrome (TS). Materials and methods: FISH and PCR were performed for the presence of chromosome mosaicism and Y-derived-material and genetic findings were correlated to clinical data. Results: Thirty-one participants were enrolled: 18 (58%) had chromosome mosaicisms (FISH), Y-derived material was found in 2. Yet, SRY primer was found with PCR in only one of them and DYZ3 was not found. The most frequent clinical findings were short or webbed neck (81,82%), high-arched palate (78%), breast hypertelorism, e cubitus valgus and genu valgus (57.6%, both), short fourth metacarpals (46.9%), epicanthic folds (43.8%), shield chest (43.8%), lymphedema (37.5%), and low set ears (34.4%). Both patients with Y-derived-material had primary amenorrhea, dyslipidemia and reached the height of 150 cm despite not treated with recombinant growth hormone (GHr). One of them showed 26% of leukocytes with Y-derived material and few clinical findings. Conclusions: FISH techniques proved efficient in detecting chromosome mosaicisms and Y-derived material and searching in different tissues such as mouth cells is critical due to the possibility of tissue-specific mosaicism. Phenotypical variance in TS may be a signal of chromosome mosaicisms, especially with the presence of Y-derived material.

Searching chromosome mosaicisms in 45,X Turner syndrome: how relevant is it?

OBJECTIVE: To investigate the presence of chromosome mosaicism, especially for the presence of Y derived material in 45,X women with Turner syndrome (TS). METHODS: FISH and PCR were performed for the presence of chromosome mosaicism and Y-derived-material and genetic findings were correlated to clinical data. RESULTS: Thirty-one participants were enrolled: 18 (58%) had chromosome mosaicisms (FISH), Y-derived material was found in 2. Yet, SRY primer was found with PCR in only one of them and DYZ3 was not found. The most frequent clinical findings were short or webbed neck (81,82%), high-arched palate (78%), breast hypertelorism, e cubitus valgus and genu valgus (57.6%, both), short fourth metacarpals (46.9%), epicanthic folds (43.8%), shield chest (43.8%), lymphedema (37.5%), and low set ears (34.4%). Both patients with Y-derived-material had primary amenorrhea, dyslipidemia and reached the height of 150 cm despite not treated with recombinant growth hormone (GHr). One of them showed 26% of leukocytes with Y-derived material and few clinical findings. CONCLUSION: FISH techniques proved efficient in detecting chromosome mosaicisms and Y-derived material and searching in different tissues such as mouth cells is critical due to the possibility of tissue-specific mosaicism. Phenotypical variance in TS may be a signal of chromosome mosaicisms, especially with the presence of Y-derived material.

Clinical and cytogenetic characteristics of patients diagnosed with Turner syndrome in a clinical genetics service: cross-sectional retrospective study

ABSTRACT BACKGROUND: Turner syndrome (TS) is a rare genetic disease. Understanding its clinical findings contributes to better management of clinical conditions. OBJECTIVE: To investigate the clinical and karyotypic characteristics of patients diagnosed with TS at two reference services for clinical genetics in southern Brazil. DESIGN AND SETTING: Retrospective cross-sectional study conducted in two clinical genetics services in Porto Alegre (RS), Brazil. METHODS: The sample consisted of 59 patients with TS diagnosed from 1993 to 2019. A review of their medical records was performed and a standard protocol was filled out. RESULTS: The average age of the patients at diagnosis was 15.9 years, and 40.7% were over 13 years old. The largest proportion of them (42.4%) had been referred from an endocrinology department and their constitution was 45,X (40.7%). The most common clinical findings were short stature (85.7%), hypoplastic/ hyperconvex nails (61.2%), low posterior hairline (52.1%) and cubitus valgus (45.8%). There was no difference regarding the presence of short stature (P = 0.5943), number of dysmorphia (P = 0.143), anatomical regions affected and malformations identified through imaging examinations (P = 1.0000), regarding the presence or absence of 45,X constitution. Only 6% of the patients had used growth hormone and 43%, estrogen. CONCLUSION: We found that, in general, patients with TS were being diagnosed late. This has important implications for their treatment. In addition, only a small proportion of the patients were undergoing further examination or evaluation, which appeared to be leading to underdiagnosis of many abnormalities.

Clinical phenotype and management of individuals with mosaic monosomy X with Y chromosome material stratified by genital phenotype.

Individuals mosaic for monosomy X and a cell line with Y chromosome material can have genitalia that appear phenotypical female, male, or ambiguous. Those with this karyotype and typical female genitalia are diagnosed with Turner syndrome; however, this definition specifically excludes those with genitalia other than typical female. There is limited information on whether medical and neurodevelopmental risks are similar among individuals with monosomy X and Y chromosome material across genital phenotypes. This multicenter retrospective study compared comorbidities and clinical management in individuals with monosomy X and Y material and male/ambiguous genitalia to those with typical female genitalia. Electronic medical records for all patients with monosomy X and Y material (n = 76) at two large U.S. pediatric centers were abstracted for predetermined data and outcomes. Logistic regression was used to compare the two phenotypic groups adjusting for site and duration of follow-up. The male/ambiguous genitalia group was just as likely to have congenital heart disease (RR 1.0, 95%CI [0.5-1.9]), autoimmune disease (RR 0.6 [0.2-1.3]), and neurodevelopmental disorders (RR 1.4 [0.8-1.2]) as those with female genitalia. Despite similar risks, they were less likely to receive screening and counseling. In conclusion, individuals with monosomy X and Y chromosome material have similar medical and neurodevelopmental risks relative to individuals with Turner syndrome regardless of genitalia, but there are notable differences in clinical management.

Outcome of 45,X fetuses with cystic hygroma: A systematic review.

This objective of this systematic review was to estimate live birth rate and explore prognostic indicators in fetuses with 45,X karyotype and a posterior cystic hygroma (CH). Electronic databases were searched and studies reporting pregnancy outcomes (termination, spontaneous abortion, demise, or live birth) for fetuses with 45,X karyotype and a CH diagnosed on ultrasound were included. For cases of survival, CH characteristics, presence of hydrops fetalis, or concomitant anomalies, delivery details, and postnatal outcomes were summarized. A total of 95 studies, including 535 cases, met inclusion criteria: 285 (53.3%) pregnancies were terminated, 72 (13.5%) had spontaneous abortion or demise, 164 (30.7%) had unspecified pregnancy failure, and 14 (2.6%) were live births. Among live births with data available, all CH measured 2-7 cm, more than half were septate, and almost all regressed in size or eventually disappeared. Hydrops fetalis was noted in five cases. Of the eight live births with neonatal outcomes available, three neonates died shortly after birth and five survived past the neonatal period. This review suggests that diagnosis of CH in a 45,X fetus is associated with an estimated live birth rate of 2.6%, but only 1% survive to infancy. Prognosis appears to improve with CH regression.

Urogenital Hypoplasia and X Chromosome Monosomy in a Draft Horse Filly.

A 5-month-old draft horse filly was presented with incontinence and severe perivulvar dermatitis, which developed during the previous 2 months. Left-sided ectopic ureter entering in the caudal vaginal lumen, signs of cervix hypoplasia, and urine accumulation in the uterus were found during initial vaginal endoscopy. Therefore, a left ureter-nephrectomy was conducted under general anesthesia. Additionally, a cytogenetic examination was performed, which showed a XO monosomy with a 63,X/64,XX mosaic. This is the first case report presenting a chromosome abnormality in a draft horse filly combined with a left-sided ectopic ureter. Cytogenetic evaluation is recommended in any female horse with developmental abnormalities of the cervix, uterus, ovaries, or with irregularities of estrus.

Premature ovarian insufficiency in the XO female mouse on the C57BL/6J genetic background.

In humans, all but 1% of monosomy 45.X embryos die in utero and those who reach term suffer from congenital abnormalities and infertility termed Turner's syndrome (TS). By contrast, XO female mice on various genetic backgrounds show much milder physical defects and normal fertility, diminishing their value as an animal model for studying the infertility of TS patients. In this article, we report that XO mice on the C57BL/6J (B6) genetic background showed early oocyte loss, infertility or subfertility and high embryonic lethality, suggesting that the effect of monosomy X in the female germline may be shared between mice and humans. First, we generated XO mice on either a mixed N2(C3H.B6) or B6 genetic background and compared the number of oocytes in neonatal ovaries; N2.XO females retained 45% of the number of oocytes in N2.XX females, whereas B6.XO females retained only 15% of that in B6.XX females. Second, while N2.XO females were as fertile as N2.XX females, both the frequency of delivery and the total number of pups delivered by B6.XO females were significantly lower than those by B6.XX females. Third, after mating with B6 males, both N2.XO and B6.XO females rarely produced XO pups carrying paternal X chromosomes, although a larger percentage of embryos was found to be XO before implantation. Furthermore, B6.XO females delivered 20% XO pups among female progeny after mating with C3H males. We conclude that the impact of monosomy X on female mouse fertility depends on the genetic background.

Confirmatory testing illustrates additional risks for structural sex chromosome abnormalities in fetuses with a non-invasive prenatal screen positive for monosomy X.

More and more women rely on non-invasive prenatal screening (NIPS) to detect fetal sex and risk for aneuploidy. The testing applies massively parallel sequencing or single nucleotide polymorphism (SNP) microarray to circulating cell-free DNA to determine relative copy number. In addition to trisomies 13, 18, and 21, some labs offer screening for sex chromosome abnormalities as part of their test. In this study, an index neonate screened positive for monosomy X and had discordant postnatal chromosomes indicating an X;autosome translocation. This patient prompted a retrospective chart review for similar cases at a large NIPS testing center. The review found 28 patients with an abnormal NIPS for monosomy X who were eventually diagnosed with additional discrepant structural sex chromosome abnormalities including translocations, isochromosomes, deletions, rings, markers, and uniparental disomy. The majority of these were mosaic with monosomy X, but in seven cases, there was no evidence of mosaicism on confirmatory testing. The identification of multiple sex chromosome aneuploidies in these cases supports the need for additional genetic counseling prior to NIPS testing and following abnormal NIPS results that are positive for monosomy X. This finding broadens our knowledge about the variable outcomes of positive monosomy X NIPS results and emphasizes the importance of confirmatory testing and clinical follow up for these patients.