Sex Chromosome Mosaicism Research Articles

Chromosomal abnormalities in oocyte donor candidates: a French survey of over 8200 karyotypes

To study karyotypes of more than 8,200 oocyte donor candidates in nulliparous or multiparous women compared to a reference population. A retrospective observational multicentric study. The study included two cohorts of oocyte donor candidates recruited between January 2005 and October 2021: multiparous women with at least one child at the time of recruitment, and nulliparous women. Both were compared to a reference population composed of female newborns from literature. Not applicable. Blood lymphocyte karyotype. A total of 8229 oocyte donor candidates from 22 fertility centers were included in this study. Nulliparous women (n=1890) and multiparous ones (n=6339) were compared to 8102 female newborns. Overall, 65 candidates were carriers of chromosomal abnormalities and were therefore excluded from the donation process (0.79%, 95% CI: 0.60-0.98). The occurrence of balanced structural chromosomal rearrangements was globally increased in the study population (0.49%, 95% CI: 0.34-0.64) compared to female newborns (0.24%, 95% CI: 0.34-0.64, p=0.0086). The number of reciprocal translocations was increased 5-fold in nulliparous oocyte donor candidates (0.37%, 95% CI: 0.10-0.64, p=0.013). The incidence of sex chromosome mosaicism was notably increased in multiparous oocyte donor candidates, with 17 cases (0.27%, 95% CI: 0.14-0.40, p=0.0052). Among chromosomal aberration carriers only two nulliparous women (one reciprocal translocation and one sex chromosome mosaicism) had fertility issues with a diagnosis of premature ovarian failure. In this comprehensive 16-years French experience of karyotyping in oocyte donor candidates, we confirmed an increased incidence of balanced structural chromosomal rearrangements, especially among those without children at the time of recruitment. Karyotyping could be considered to identify any chromosomal abnormalities that may not be easily detectable through medical questioning. These abnormalities pose an inherent genetic risk for gamete recipients if left undetected.

P-563 Improved diagnosis in PGT-A samples with intermediate sex chromosomes copy number changes by adding ploidy and contamination analysis

Abstract Study question Does triple analysis of aneuploidy, ploidy and contamination improve the diagnosis in samples with intermediate copy number changes for the X and the Y chromosomes? Summary answer PGT-A with additional ploidy and contamination analysis improves the diagnosis of samples with intermediate sex chromosomes copy number changes, reducing non-informativity and the re-biopsy need. What is known already Next Generation Sequencing (NGS) in Preimplantation Genetic Testing for Aneuploidies (PGT-A) identifies chromosomal aneuploidies in trophectoderm (TE) biopsies. However, diagnosis limitations exist when the TE biopsy displays intermediate copy number changes for the X and the Y chromosomes, observed in ∼0.3% of biopsies. Few explanations are plausible, including mosaicism for the sex chromosomes, presence of exogenous DNA contamination or triploidy. A second TE biopsy (re-biopsy) could be recommended to obtain a conclusive result. However, additional Single Nucleotide Polymorphism (SNP) analysis to determine the ploidy status of the embryo and the presence of contamination in the biopsy can be an alternative. Study design, size, duration In this retrospective study, the impact on the diagnosis of SNPs analysis with a target panel was evaluated in PGT-A samples showing intermediate copy number changes for the X and the Y chromosomes. A total of 21 TE biopsies from January to December 2023 were included in the study. Participants/materials, setting, methods The TE biopsies were analysed using NGS with a proprietary protocol for library preparation, Ion Chef and Ion S5 System instruments for sequencing and a proprietary bioinformatics pipeline (v2.0) for 24-chromosomes aneuploidy testing. A re-biopsy was analysed in 8 embryos using the same protocol. Eighteen original biopsies were retrospectively evaluated for ploidy and contamination using an Ion AmpliSeq Custom Panel including SNPs (Thermo Fisher Scientific, USA) and a proprietary algorithm (v1.0) for data analysis. Main results and the role of chance The 21 TE biopsies displaying intermediate copy number changes for the X and the Y chromosomes were initially diagnosed as non-informative and candidates for re-biopsy to rescue diagnosis. A total of 8 embryos were re-biopsied (38.1%): 6 re-biopsies (75.0%) showed the same intermediate sex chromosomes copy number changes suggesting a triploid status of the embryo, 1 re-biopsy (12.5%) showed trisomy 22 suggesting DNA contamination in the original biopsy and, 1 re-biopsy (12.5%) displayed a mosaic monosomy X/XY suggesting a diploid-mosaic status of the embryo. In 18 original TE biopsies (85.7%), an additional ploidy and contamination analysis was done: 10 samples were triploid (55.6%), 6 samples showed DNA contamination (33.3%) and 2 samples were diploid (11.1%). In 5 embryos, the re-biopsy with the aneuploidy testing had been done: (i) in 4 triploid embryos the re-biopsies showed the same intermediate copy number changes for the sex chromosomes than the original biopsy, confirming the triploid status of the embryo; (ii) in 1 diploid embryo the re-biopsy showed a mosaic monosomy X/XY, confirming the diploid status and the sex chromosome mosaicism of the embryo. From the 21 embryos initially non-informative, only the 6 contaminated ones remained non-informative and candidates for re-biopsy (33.3%). Limitations, reasons for caution The limited number of samples with both analysis, ploidy/contamination by SNPs in the original sample and aneuploidy by NGS in the re-biopsy precluded to drawn stronger conclusions. This double-check would reinforce the benefit of doing additional ploidy/contamination analysis in these specific cases. Wider implications of the findings A high incidence of samples with intermediate sex chromosomes copy number are triploid, some have exogenous DNA contamination, and few are real mosaics for the sex chromosomes. Additional ploidy and contamination analysis could improve the PGT-A diagnosis and decrease mosaicism and non-informativity rates, reducing the embryos that would need re-biopsy. Trial registration number Not applicable

A Novel Method for Acquired Sex Chromosome Mosaicism.

The phenomenon of sex chromosome loss from hematopoietic cells is an emerging indicator of biological aging. While many methods to detect this loss have been developed, enhancing the field, these existing methods often suffer from being labor-intensive, expensive, and not sufficiently sensitive. To bridge this gap, a novel and more efficient technique is developed, named the SinChro assay. This method employs multiplexed single-cell droplet PCR, designed to detect cells with sex chromosome loss at single-cell resolution. Through the SinChro assay, the age-dependent increase in Y chromosome loss in male blood is successfully mapped. The age-dependent loss of the X chromosome in female blood is also identified, a finding that has been challenging with existing methods. The advent of the SinChro assay marks a significant breakthrough in the study of age-related sex mosaicism. Its utility extends beyond blood analysis, applicable to a variety of tissues, and it holds the potential to deepen the understanding of biological aging and related diseases.

Comparison of detection rates of chromosome G-banding karyotype analysis and fluorescence in situ hybridization among children with sex chromosome mosaicisms

To explore the coincidence rate of G-banding karyotype analysis and fluorescence in situ hybridization (FISH) for the diagnosis of children with sex chromosome mosaicisms. A retrospective analysis was carried out for 157 children with suspected sex chromosome abnormalities who had presented at Shenzhen Children's Hospital from April 2021 to May 2022. Interphase sex chromosome FISH and G-banding karyotyping results were collected. The coincidence rate of the two methods in children with sex chromosome mosaicisms was compared. The detection rates of G-banding karyotype analysis and FISH were 26.1% (41/157) and 22.9% (36/157) , respectively (P > 0.05). The results of G-banding karyotype analysis showed that 141 cases (89.8%) were in the sex chromosome homogeneity group, of which only 5 cases (3.5%) were inconsistent with the results of FISH. There were 16 cases (10.2%) in the sex chromosome mosaicism group, of which 11 cases (68.8%) were inconsistent with the results of FISH. There was a statistical difference between the two groups in the coincidence rate of the results of the two methods (P < 0.05). No significant difference was found between G-banding karyotype analysis and FISH in the detection rate of chromosome abnormalities. The coincidence rate in the mosaicism group was lower than that in the homogeneity group, and the difference was statistically significant. The two methods should be combined for clinical diagnosis.

Application of chromosome microarray analysis and karyotyping in diagnostic assessment of abnormal Down syndrome screening results

BackgroundDown syndrome (DS) is the most common congenital cause of intellectual disability and also leads to numerous metabolic and structural problems. This study aims to explore the application value of chromosomal microarray analysis (CMA) and karyotyping in prenatal diagnosis for pregnant women with abnormal DS screening results.MethodsThe study recruited 1452 pregnant women with abnormal DS screening results including 493 with an enlarged nuchal translucency thickness (NT ≥ 2.5 mm) and 959 with an abnormal second-trimester maternal serum biomarker screening results. They underwent amniocentesis to obtain amniotic fluid for CMA and karyotyping.ResultsCMA identified 74/1452 abnormal results, which was more efficient than karyotyping (51/1452, P < 0.05.) CMA is equivalent to traditional karyotyping for identifying aneuploidies. Compared to karyotyping CMA identified 1.90% more copy number variants (CNVs) ranging from 159Kb to 6496Kb. However, 34.4% of them were recurrent pathogenic CNVs associated with risk of neurodevelopmental disorders. CMA identified 13 variants of uncertain significance (VUS) results and 1 maternal uniparental disomy (UPD) of chromosome 7. Karyotyping identified 3 mosaic sex chromosome aneuploidy and 4 balanced translocation which could not be identified by CMA. In enlarged NT group, karyotyping identified 80.9% abnormal results while in serum screening group karyotyping identified 35.7%. However, the incidence of pathogenic/likely pathogenic (P/LP) CNVs was nearly the same in both groups. That was because aneuploidies and gross duplication/deletion were previously screened out by NT scan.ConclusionsCMA and karyotyping have both advantages and disadvantages in prenatal diagnosis of pregnant women with abnormal DS screening results. However, there was not enough evidence to support routine CMA in pregnant women with abnormal DS screening results.

Determining chorionicity and amnionicity in twin pregnancies: Pitfalls.

Although the accuracy of chorioamnionicity determination in multiple pregnancy is nearly 100%, some pitfalls do exist. These pitfalls may arise from some confusing sonographic appearance or because of certain rare variations of twinning going against the general principles. Pitfalls in chorionicity determination include (1) the disappearance of the twin peak sign with the regression of chorion frondosum and thinning of the intertwin membrane with advancing gestation; (2) fake twin peak sign because of other structures creeping into the intertwin membrane-placental junction; (3) intrauterine septum or synechia being mistaken as a thick intertwin membrane; (4) bipartite placenta in monochorionic twin being misinterpreted as two separate placentas of dichorionic twin; (5) erroneous fetal sex determination in sex chromosome mosaicism, monogenic disorders, and malformed genitalia in one fetus; and (6) rare twinning types such as dizygotic monochorionic twin and sesquizygotic twin. Pitfalls in amnionicity determination are (1) the lack of correlation between the number of yolk sacs and amnionicity and (2) failure to visualize the intertwin membrane because of technical issues.

Non-invasive preimplantation genetic testing for conventional IVF blastocysts

BackgroundPrevious studies suggested that non-invasive preimplantation genetic testing (niPGT) for intracytoplasmic sperm injection (ICSI) blastocysts can be used to identify chromosomal ploidy and chromosomal abnormalities. Here, we report the feasibility and performance of niPGT for conventional in vitro fertilization (IVF) blastocysts.MethodsThis was a prospective observational study. In the preclinical stage, whole genome amplification and NGS were performed using the sperm spent culture medium (SCM). Then, trophectoderm (TE) biopsies and corresponding SCM derived from 27 conventional IVF monopronuclear embryos were collected. In the clinical stage, samples from 25 conventional IVF cycles and 37 ICSI cycles from April 2020–August 2021 were collected for performance evaluation.ResultsPreclinically, we confirmed failed sperm DNA amplification under the current amplification system. Subsequent niPGT from the 27 monopronuclear blastocysts showed 69.2% concordance with PGT results of corresponding TE biopsies. In the clinical stage, no paternal contamination was observed in any of the 161 SCM samples from conventional IVF. While maternal contamination was observed in 29.8% (48/161) SCM samples, only 2.5% (4/161) samples had a contamination ratio ≥ 50%. Compared with that of TE biopsy, the performances of NiPGT from 161 conventional IVF embryos and 122 ICSI embryos were not significantly different (P > 0.05), with ploidy concordance rates of 75% and 74.6% for IVF and ICSI methods, respectively. Finally, evaluation of the euploid probability of embryos with different types of niPGT results showed prediction probabilities of 82.8%, 77.8%, 62.5%, 50.0%, 40.9% and 18.4% for euploidy, sex-chromosome mosaics only, low-level mosaics, multiple abnormal chromosomes, high-level mosaics and aneuploidy, respectively.ConclusionsOur research results preliminarily confirm that the niPGT approach using SCM from conventional IVF has comparable performance with ICSI and might broadening the application scope of niPGT.

Application of the prenatal BACs-on-Beads™ assay for rapid prenatal detection of sex chromosome mosaicism

The prenatal BACs-on-Beads™ (BoBs) assay was introduced for rapid detection of abnormalities of chromosomes 13, 18, 21, X, and Y and specific nine significant microdeletion syndromes. The ability of prenatal BoBs to detect mosaicism ranged from 20 to 40%. However, there have been no prenatal studies of sex chromosome mosaicism in prenatal BoBs. Therefore, the present study was performed with an aim to uncover the detection level of sex chromosome mosaicism that application of prenatal BoBs assay, and then to assess the sensitivity of prenatal BoBs assay, thereby improving the prenatal diagnostic accuracy. A total of 31 samples of amniotic fluid (AF) and umbilical cord blood (UCB) for prenatal diagnosis were collected, and the results were confirmed through karyotyping, single nucleotide polymorphism microarray (SNP-array) and copy number variation sequencing (CNV-seq). 23 cases of sex chromosome mosaicism were prompted abnormal by prenatal BoBs, the minimum detection level of mosaicism was about 6% as detected by karyotype. The overall sensitivity of prenatal BoBs in the detection of sex chromosome mosaicism was 74.2% (23/31). This study evaluated the effectiveness of prenatal BoBs for detecting sex chromosome mosaicism in prenatal diagnosis, and the results will provide valuable information for genetic counseling.

Prenatal screening and diagnosis for a fetus with mosaic sex chromosome abnormality

To carry out prenatal screening and diagnosis for a woman with advanced maternal age. Non-invasive prenatal testing (NIPT) was carried out to determine the risk of fetal chromosome aneuploidy. Aminiocentesis was proceeded for fetal chromosomal karyotyping and copy number variation sequencing (CNV-seq). The fetus was subjected to systematic ultrasound screening in the second trimester. NIPT has indicated there was a loss of fetal sex chromosome. Karotyping of the amniocyte showed a mosaic sex chromosome abnormality 45,X[53]/46,X,+mar[7]. The result of fetal DNA CNV-seq was seq[GRCh37]del(Yq11.1q12) chrY: g.13 104 553-28 819 361del, seq[GRCh37]del(Yp11.32p11.2) chrY: g.10 001-9 873 915del (mosaic ratio: 30%). Ultrasonography discovered that the fetus had renal dysplasia and male external genitalia. The karyotypes of the couple were both normal. Multiple genetic tests should be carried out for fetus with a high risk for chromosome aneuploidies signaled by NIPT. It is difficult to predict the post-natal phenotype for fetuses with mosaic sex chromosomal aneuploidies. The couple should be carefully counseled upon genetic counseling.

Turner Syndrome

Turner syndrome (TS) affects approximately 1 out of every 1500–2500 live female births, with clinical features including short stature, premature ovarian failure, dysmorphic features and other endocrine, skeletal, cardiovascular, renal, gastrointestinal and neurodevelopmental organ system involvement. TS, a common genetic syndrome, is caused by sex chromosome aneuploidy, mosaicism or abnormalities with complete or partial loss of function of the second X chromosome. Advances in genetic and genomic testing have further elucidated other possible mechanisms that contribute to pathogenic variability in phenotypic expression that are not necessarily explained by monosomy or haploinsufficiency of the X chromosome alone. The role of epigenetics in variations of gene expression and how this knowledge can contribute to more individualized therapy is currently being explored. TS is established as a multisystemic condition, with several endocrine manifestations of TS affecting growth, puberty and fertility having significant impact on quality of life. Treatment guidelines are in place for the management of these conditions; however, further data on optimal management is needed.

Cytogenetic abnormalities in a sample of females with premature ovarian failure

BackgroundPremature ovarian failure (POF) is a complex heterogeneous disorder characterized by the triad of amenorrhea, hypergonadotropinism, and hypoestrogenism in women before the expected age of menopause. In most POF patients, the etiology is idiopathic. X chromosome abnormalities are known to be responsible for many POF cases but the effect of sex chromosome low level mosaicism on ovarian function still remains unclear. The aim of this study was to investigate the prevalence and type of cytogenetic abnormalities as well as low-level sex chromosome mosaicism in Egyptian females with POF.ResultsThe present study recruited thirty women with POF and thirty women with normal reproductive history as a control group. Conventional cytogenetic analysis was carried out on POF patients in order to detect cytogenetic abnormalities. FISH on interphase and metaphase nuclei from patients with normal karyotype as well as from thirty control women with normal reproductive history was performed using X, Y, and 18 centromeric probes to evaluate low-level sex chromosome mosaicism. Conventional cytogenetic analysis of peripheral blood lymphocytes demonstrated chromosomal aberrations in 7 cases. FISH revealed that the rate of X chromosome mosaicism was significantly higher in POF patients than in the control group.ConclusionWe concluded that X chromosome abnormalities including low level mosaicism may be underlying the pathology of POF as increased mosaicism may lead to accelerated oocyte aging and premature follicular atresia.

Contribution of maternal mosaicism to false-positive chromosome X loss associated with noninvasive prenatal testing

Objective To report the frequency of maternal mosaicism contributing to false-positive chromosome X loss associated with noninvasive prenatal testing (NIPT) at a single center. Methods Pregnancies undergone NIPT using massively parallel sequencing at Guangzhou Women and Children’s Medical Center between February 2015 and May 2020 were included in this study. Fetal karyotyping, quantitative fluorescence PCR (QF-PCR) or microarray analysis was provided to patients with abnormal sex chromosomal aneuploidy (SCA) results for confirmatory testing, and QF-PCR was also employed to detect maternal sex chromosome status. Results cffDNA testing of 40682 pregnancies revealed 86 cases with NIPT results positive for chromosome X loss (0.21%). Among the 86 high-risk cases, 73 women had undergone confirmatory testing in our center, whereas 13 declined. Of the 73 women verified by invasive prenatal diagnosis, 27.4% (20/73) were true positive cases including six cases of monosomy X, two cases of microdeletion of Xp22.33, one case of deletion Xq27.2q28, one case of 47, XXX and ten cases with fetal sex chromosome mosaicism. Of the remaining 53 patients with fetal normal results, 30 cases had undergone QF-PCR analysis of maternal white blood cells. QF-PCR indicated that 36.7% (11/30) patients had an altered or mosaic maternal sex chromosome status. Statistical analysis indicated that cell-free fetal DNA (cffDNA) concentration estimated by chromosome X in maternal mosaic cases was significantly higher than that in the non-maternal mosaicism group (p < .05) and was related to maternal mosaicism rate (r = 0.88, p < .05). Conclusions Our findings indicated that maternal mosaicism of sex chromosome was not uncommon in false-positive NIPT chromosome X loss cases. We recommend that this information should be disclosed to pregnancies during clinical counseling and maternal sex chromosome status should be confirmed for the cases with NIPT chromosome X loss.

Clinical Selection of Prenatal Diagnostic Techniques Following Positive Noninvasive Prenatal Screening Results in Southwest China.

Background: This study aims to evaluate prenatal diagnosis methods following positive noninvasive prenatal screening (NIPS) results. Methods: According to the positive noninvasive prenatal screening results, 926 pregnant women were divided into three groups: main target disease group (high risk for trisomy 21, trisomy 18, or trisomy 13), sex chromosome aneuploidy (SCA) group, and other chromosomal abnormalities group [abnormal Z-scores for chromosomes other than trisomy (T)21/T18/T13 or SCAs]. The verification methods and results were then retrospectively analysed. Results: In the main target disease group, the positive rate of chromosomal abnormalities confirmed by quantitative fluorescence polymerase chain reaction (QF-PCR) was 75.18% (212/282), which was not significantly different from that by karyotyping (79.36%, 173/218) and copy number variation (CNV) detection methods (71.43%, 65/91). The positive rate of additional findings confirmed by karyotyping and copy number variation detection methods in main target disease group was 0.46% (1/218) and 8.79% (8/91), respectively. The positive rate of chromosomal abnormalities confirmed by karyotyping and CNV detection methods were 27.11% (45/166) and 38.46% (95/247) in the SCA group and 4.17% (1/24) and 20% (36/180) in the other chromosomal abnormalities group, respectively. Fetal sex chromosome mosaicism was detected in 16.13% (20/124) of the confirmed SCA cases. There were no significant differences in the detection rates of chromosomal microarray analysis (CMA) and CNV sequencing (CNVseq) among the three groups (p > 0.05). Conclusion: QF-PCR can quickly and accurately identify aneuploidies following NIPS-positive results for common aneuploidy, and in combination with karyotyping and CNV detection techniques can provide more comprehensive results. With the NIPS-positive results for SCA or other abnormalities, CMA and CNVseq may have the same effect on increasing the detection rate. The addition of fluorescence in situ hybridization assay may help to identify true fetal mosaicism.

Prenatal diagnosis and genetic counseling of low-level sex chromosomal mosaicism with a favorable outcome

Prenatal diagnosis and genetic counseling of low-level sex chromosomal mosaicism with a favorable outcome

Disorders of Sex Development.

Disorders of Sex Development.

50 Years Ago in TheJournalofPediatrics: To Every Season Turner, Turner, Turner

Hsu LY, Hirschhorn K. Unusual Turner mosaicism (45,X/47,XXX; 45,X/46,XXqi; 45,X/46,XXr): detection through linear deceleration from normal linear growth or secondary amenorrhea. J Pediatr 1971;79;2:276-81. It is said that the “post-human genome-sequencing project era” of genomic medicine is like no other. New genes, genomic mechanisms, and associated human phenotypes are being deciphered at a staggering pace. In fact, we are walking a worn path, laid by pioneers of the medical cytogenetics era like Drs Hsu and Hirschhorn. The current number of human chromosomes were not accurately identified until 1956.1Tjio J.H. Levan A. The chromosome number of man.Hereditas. 1956; 42: 1-6Crossref Scopus (566) Google Scholar A short 3 years later, the association between 45,X and Turner syndrome was recognized and, along with it, the first report of sex chromosome mosaicism.2Ford C.E. Jones K.W. Polani P.E. De Almeida J.C. Briggs J.H. A sex-chromosome anomaly in a case of gonadal dysgenesis (Turner’s syndrome).Lancet. 1959; 276: 711-712Abstract Scopus (531) Google Scholar,3Ford C.E. Polani P.E. Briggs J.H. Bishop P.M. A presumptive human XXY/XX mosaic.Nature. 1959; 183: 1030-1032Crossref PubMed Scopus (36) Google Scholar Only 15 years after the number of human chromosomes was announced, Hsu and Hirschhorn described 3 unusual 45,X mosaic variants and their phenotypes. They identify that growth deceleration, not just short stature from birth, and secondary amenorrhea, not just primary, can be associated with variant Turner syndrome. This march of refining and expanding the phenotype and prognosis associated with a new genetic syndrome is familiar. In the same way today, new gene/disease associations are made based on the most “severely” affected individuals. Then, as less obviously affected individuals are confirmed or identified genetically, the list of features and our understanding of the highly variable expression of syndromic presentations expands. This process of phenotype identification, its refinement, and analysis of potential mechanism continues perhaps indefinitely. Even now, we are identifying new phenotypes associated with classical Turner syndrome (eg, hyperinsulinism).4Gibson C.E. Boodhansingh K.E. Li C. Conlin L. Chen P. Becker S.A. et al.Congenital hyperinsulinism in infants with turner syndrome: possible association with monosomy X and KDM6A haploinsufficiency.Horm Res Paediatr. 2018; 89: 413-422Crossref PubMed Scopus (16) Google Scholar In the most recent decade, with the advent of clinically noninvasive prenatal screening for approximate sex chromosome count, the phenotype of 45,X-mosaic individuals is widening yet further. Today, these patients would have been screened for further mosaicism and Y-chromosome by genome-wide array. Our nomenclature too has shifted, in ways small and large. Terms like “sexual infantilism” are considered value-laden and no longer acceptable, nor is revealing photography like the fully unclothed woman with a small black oval over the eyes. Yet many things are relatively unchanged. In conjunction with new diagnostic tools like noninvasive prenatal screening and genome-wide arrays, the karyotype is still key for diagnosis of structures like the ring-X described in patient three. By carefully, painstakingly phenotyping, and genetically characterizing their patients, Hsu and Hirschhorn were able to expand Turner variant phenotypes and the relationship to diagnostic karyotypes. The tools and knowledge base of genomic medicine are vastly expanded, but 50 years later, our approach is fundamentally the same.

Molecular diagnosis of sex chromosome mosaics in fetal amniotic cells.

Mosaicism can be observed in karyotype analyses of amniotic fluid cells. Differentiating between true mosaicism and pseudomosaicism and determining mosaic proportions can help avoid misjudgments by doctors and effectively reduce mental and physical harm to pregnant women. However, the detection of mosaicism and mosaic proportions via karyotype analysis and fluorescence in situ hybridization (FISH) is extremely complex. We have developed a novel approach, “segmental duplication quantitative fluorescent PCR” (SD-QF-PCR), to detect mosaicism and mosaic proportions.In this study, twenty control samples and fourteen mosaic samples were tested by first-line karyotype analysis; by second-line karyotype analysis, SD-QF-PCR and FISH were used to reassess fetal sex chromosome mosaicism and mosaic proportions.Detection of the 20 control samples by second-line karyotype analysis via FISH and SD-QF-PCR showed normal and consistent results. Among the 14 mosaic samples, the numbers of samples showing true mosaicism and pseudomosaicism detected by the three methods were 6 and 8, respectively.Our study demonstrates that SD-QF-PCR can be used as a complementary method to traditional cytogenetic analysis of amniotic fluid mosaics and has clinical application value.

The Evaluation of Parental Acceptance Towards Children with Sex Chromosomal Disorders of Sex Development Using A Mixed-Method

Background: Sex chromosomal Disorder of sex development (DSD) is an atypical abnormality of external genitalia which is mismatched with its sex chromosome traits. The condition of children with DSD affects the dynamics in the family. Parents’ reactions after discovering this health problem vary greatly, such as being in a state of shock, confusion, or self-blame. However, parents’ acceptance is extremely important for better quality of caring, to the healthy social and emotional child development, and to make the best decisions regarding gender assignment.Objective: To describe the acceptance process of parents that have children with sex chromosomes mosaicism DSD.Methods: This study used a mixed-method with a sequential explanatory approach, which was preceded by quantitative data collection followed by qualitative. The total respondents consisted of 14 mothers and 12 fathers of 14 sex chromosome mosaicism DSD patients with XX/XY, X/XY, XYY or XXY variants. Quantitative data were collected using the Indonesian version of the Parental Acceptance-Rejection Questionnaire (PARQ), and interviews were conducted to determine the acceptance process.Results: Most acceptance cases were based on the surgical stage completion in which a higher number of mothers (71.43%) than fathers (50%).Conclusion: It is uneasy for parents to accept children with sex chromosome mosaicisms DSD, hence the fathers struggle more than mothers in accepting those affected. To the best of our knowledge this is the first study in Indonesia to help parent understand and accept their child condition.

Disorder of Sexual Development Males With XYY in Blood Have Exactly X/XY/XYY Mosaicism in Gonad Tissues.

Y chromosome represents masculinization. The extra Y chromosome of XYY patients usually leads to over-masculinization phenotypes. The occurrence of several DSD cases with XYY in blood is controversial. Is XYY associated with disorder of sex development (DSD)? What is the mechanism behind DSD in males with XYY in blood? To this end, this study retrospectively analyzed blood-karyotype data of 4,437 DSD male children and karyotypes data of 6,259 newborn males as the control. Exome sequencing (ES) was performed to test whether the patients with DSD and with XYY in blood had other variants on known DSD-genes. Testicular biopsy was performed. Fluorescence in situ hybridization (FISH) was used to test whether a sex chromosome mosaicism was present in the oral epithelial cells or gonad tissue of patients with DSD and with XYY in blood. Among 4,437 DSD males who received cytogenetic evaluation, 14 patients with 47,XYY were identified. By contrast, five individuals among the 6,259 controls had 47,XYY. XYY in blood is more frequent among males with DSD than in other males (p = 0.004). The XYY karyotypes were confirmed again by GTG-banding in blood samples and by FISH performed on oral epithelial cells. ES on seven XYY DSD patients was successfully performed, but results did not identify any pathogenic variant on 55 known DSD genes. Gonad biopsy (n = 3) revealed testicular dysplasia and true hermaphroditism. FISH of gonad tissues (n = 3) showed that all of the samples had mosaic for X/XY/XYY. This study is the first to investigate the relationship between XYY in blood and DSD. The knowledge that XYY is in the blood and in oral cells have X/XY/XYY mosaicism in gonadal tissue is new for both researchers and clinicians who seek to understand the genetic basis of DSD males.

Whether to transfer mosaic embryos: a cytogenetic view of true mosaicism by amniocentesis

Research questionPreimplantation genetic testing for aneuploidies has increasingly been employed for embryo selection, resulting in a recent surge in mosaic embryos. According to the cytogenetic results, which types of mosaic embryo survive early pregnancy, progress to the second trimester and finally result in a live birth? DesignThis study evaluated 30,587 pregnant women undergoing amniocentesis from January 2004 to March 2020 at the cytogenic centre of Kaohsiung Chang Gung Memorial Hospital. Samples from amniocentesis were cultured using the in-situ method. The types and distribution of level III chromosomal mosaicism (two or more cells with the same abnormality in two or more colonies and both culture dishes, clinically referred to as ‘true mosaicism’) were retrospectively reviewed. ResultsAmong the 30,587 women, 78 cases (0.26%) of level III chromosomal mosaicism were identified. The types of chromosomal mosaicism were classified as sex chromosome mosaicism (SCM), autosomal chromosome mosaicism (ACM) and marker chromosome mosaicism (MCM), with SCM, ACM and MCM accounting for 58.97%, 32.05% and 8.97% of cases, respectively. The most common mosaic cell lines were monosomy X and trisomy 21. The most common mosaic cell line progressing to live birth was monosomy X. ConclusionsMosaic monosomy X and trisomy 21 are the most common cell lines of true mosaicism determined by amniocentesis. Monosomy X mosaicism is the most common cell line in live births. For women considering the transfer of these types of mosaic embryo in a circumstance where euploid embryos are unavailable, clinicians should provide careful prenatal counselling, detailed ultrasonography and amniocentesis.