A cytogenetic survey of 14,069 newborn infants. I. Incidence of chromosome abnormalities

Resolution of ring chromosomes, Robertsonian translocations, and complex structural variants from long-read sequencing and telomere-to-telomere assembly

Delineation of structural variants (SVs) at sequence resolution in highly repetitive genomic regions has long been intractable. The sequence properties, origins, and functional effects of classes of genomic rearrangements such as ring chromosomes and Robertsonian translocations thus remain unknown. To resolve these complex structures, we leveraged several recent milestones in the field, including (1) the emergence of long-read sequencing, (2) the gapless telomere-to-telomere (T2T) assembly, and (3) a tool (BigClipper) to discover chromosomal rearrangements from long reads. We applied these technologies across 13 cases with ring chromosomes, Robertsonian translocations, and complex SVs that were unresolved by short reads, followed by validation using optical genome mapping (OGM). Our analyses resolved 10 of 13 cases, including a Robertsonian translocation and all ring chromosomes. Multiple breakpoints were localized to genomic regions previously recalcitrant to sequencing such as acrocentric p-arms, ribosomal DNA arrays, and telomeric repeats, and involved complex structures such as a deletion-inversion and interchromosomal dispersed duplications. We further performed methylation profiling from long-read data to discover phased differential methylation in a gene promoter proximal to a ring fusion, suggesting a long-range position effect (LRPE) with heterochromatin spreading. Breakpoint sequences suggested mechanisms of SV formation such as microhomology-mediated and non-homologous end-joining, as well as non-allelic homologous recombination. These methods provide some of the first glimpses into the sequence resolution of Robertsonian translocations and illuminate the structural diversity of ring chromosomes and complex chromosomal rearrangements with implications for genome biology, prediction of LRPEs from integrated multi-omics technologies, and molecular diagnostics in rare disease cases.

Maternal cardiovascular morbidity and mortality associated with pregnancy in individuals with Turner syndrome: a committee opinion

In individuals with Turner syndrome, the risk of death from aortic dissection or rupture during pregnancy may be as high as 1%, and it is unclear whether this risk persists during the postpartum period owing to pregnancy-related aortic changes. Turner syndrome is a relative contraindication for pregnancy; however, it is an absolute contraindication for pregnancy in a patient with an aortic size index of >2.5 cm/m2 or an aortic size index of ≥2.0 cm/m2 with a documented cardiac anomaly or other risk factors. This document replaces the 2012 document of the same name.

Applicability of the External Genitalia Score (EGS) in Indian neonates and children up to 2 years of age

OBJECTIVES

To generate normative data and validate the recently developed, gender-neutral, External Genitalia Score (EGS) in Indian preterm and term neonates and children up to 2 years of age with normal and atypical genitalia.

METHODS

This observational study included 1,040 neonates born between 28 and 42 weeks of gestation and 152 children between 1 and 24 months of age. In addition, 50 children with disorders of sex development (DSD) were also enrolled in the study. The Prader stage/external masculinization score (EMS) (as applicable), anogenital ratio (AGR) and EGS were assessed for all neonates and children with typical and atypical genitalia.

RESULTS

Median EGS values in newborn males with typical genitalia were 9.5 at 28-31 weeks, 10.5 at 32-33 weeks, 11 at 34 weeks and 11.5 in males at 35-42 weeks of gestation. For all females with typical genitalia, the EGS was 0. EMS and EGS showed a positive correlation in males with typical genitalia (r=0.421, p=0.000**) and all children with DSD (r=0.857, p=0.000**). Mean AGR in males and females with typical genitalia and those with DSD were 0.52±0.07, 0.31±0.05 and 0.47±0.13, respectively. EGS correlated with AGR in all males with typical genitalia (r=0.107, p=0.008**), and in all children with DSD (r=0.473, p=0.001**).

CONCLUSIONS

The EGS enables accurate, gender-neutral and comprehensive assessment of external genitalia in Indian neonates and children with typical and atypical genitalia/DSD. Evaluation for DSD is recommended in any child with EGS greater than 0 and ≤10th percentile for gestation or age (10.5 in a term neonate).

Toward a Robust Definition of Sport Sex

Elite individual sports in which success depends on power, speed, or endurance are conventionally divided into male and female events using traditional binary definitions of sex. Male puberty creates durable physical advantages due to the 20- to 30-fold increase in circulating testosterone producing a sustained uplift in men's muscle, bone, hemoglobin, and cardiorespiratory function resulting from male puberty and sustained during men's lives. These male physical advantages provide strong justification for a separate protected category of female events allowing women to achieve the fame and fortune from success they would be denied if competing against men. Recent wider social acceptance of transgender individuals, together with the less recognized involvement of intersex individuals, challenge and threaten to defeat the sex classifications for elite individual female events. This can create unfair advantages if seeking inclusion into elite female events of unmodified male-bodied athletes with female gender identity who have gained the physical advantages of male puberty. Based on reproductive physiology, this paper proposes a working definition of sport sex based primarily on an individual's experience of male puberty and can be applied to transgender and various XY intersex conditions. Consistent with the multidimensionality of biological sex (chromosomal, genetic, hormonal, anatomical sex), this definition may be viewed as a multistrand cable whose overall strength survives when any single strand weakens or fails, rather than as a unidimensional chain whose strength is only as good as its weakest link.

Germ Cell Tumors in 46, XY Gonadal Dysgenesis

Introduction

To present the clinical data, investigative profile, management, and follow-up of patients with 46, XY gonadal dysgenesis with germ cell tumors from the endocrine unit of a tertiary care university hospital.

Materials and Methods

This retrospective study included 3 cases of 46, XY gonadal dysgenesis with germ cell tumors evaluated and managed at the Department of Endocrinology, Sher-i-Kashmir Institute of Medical Sciences, Srinagar, Kashmir, over a period of 13 years from (September 2008 to December 2021).

Results

Over a period of 13 years, we diagnosed and managed 7 patients with 46, XY gonadal dysgenesis. This included 4 patients with pure gonadal dysgenesis (PGD; Swyer syndrome), 2 patients with mixed gonadal dysgenesis (MGD), and one patient with partial gonadal dysgenesis. Out of these 7 patients, three patients developed germ cell tumors, one patient with MGD, and two patients with pure PGD (Swyer syndrome). In all three patients, germ cell tumor was the first presentation of DSD. The patient with MGD presented with primary amenorrhea and virilization, while the two patients with PGD presented as phenotypic females with primary amenorrhea and pelvic mass. All three patients developed seminomatous cancers. Patient with MGD developed seminoma and the two patients with PGD (Swyer syndrome) developed dysgerminoma. The patients were managed with bilateral gonadectomy with removal of the tumor. In addition, the 2 patients with PGD (Swyer syndrome) received combined chemotherapy. On a follow up ranging from 1 to 10 years, all three patients are disease free.

Conclusions

we conclude that germ cell tumors may be the first presentation of 46, XY gonadal dysgenesis. In all phenotypic females with primary amenorrhea and dysgerminoma, karyotype is a must to uncover the diagnosis of PGD. In addition virilization may be clue to the presence of germ cell tumor in a patient with 46, XY gonadal dysgenesis.

Clinical practice guidelines for the care of girls and women with Turner syndrome

Turner syndrome (TS) affects 50 per 100 000 females. TS affects multiple organs through all stages of life, necessitating multidisciplinary care. This guideline extends previous ones and includes important new advances, within diagnostics and genetics, estrogen treatment, fertility, co-morbidities, and neurocognition and neuropsychology. Exploratory meetings were held in 2021 in Europe and United States culminating with a consensus meeting in Aarhus, Denmark in June 2023. Prior to this, eight groups addressed important areas in TS care: (1) diagnosis and genetics, (2) growth, (3) puberty and estrogen treatment, (4) cardiovascular health, (5) transition, (6) fertility assessment, monitoring, and counselling, (7) health surveillance for comorbidities throughout the lifespan, and (8) neurocognition and its implications for mental health and well-being. Each group produced proposals for the present guidelines, which were meticulously discussed by the entire group. Four pertinent questions were submitted for formal GRADE (Grading of Recommendations, Assessment, Development and Evaluation) evaluation with systematic review of the literature. The guidelines project was initiated by the European Society for Endocrinology and the Pediatric Endocrine Society, in collaboration with members from the European Society for Pediatric Endocrinology, the European Society of Human Reproduction and Embryology, the European Reference Network on Rare Endocrine Conditions, the Society for Endocrinology, and the European Society of Cardiology, Japanese Society for Pediatric Endocrinology, Australia and New Zealand Society for Pediatric Endocrinology and Diabetes, Latin American Society for Pediatric Endocrinology, Arab Society for Pediatric Endocrinology and Diabetes, and the Asia Pacific Pediatric Endocrine Society. Advocacy groups appointed representatives for pre-meeting discussions and the consensus meeting.

A working model for the formation of Robertsonian chromosomes

Robertsonian chromosomes form by fusion of two chromosomes that have centromeres located near their ends, known as acrocentric or telocentric chromosomes. This fusion creates a new metacentric chromosome and is a major mechanism of karyotype evolution and speciation. Robertsonian chromosomes are common in nature and were first described in grasshoppers by the zoologist W. R. B. Robertson more than 100 years ago. They have since been observed in many species, including catfish, sheep, butterflies, bats, bovids, rodents and humans, and are the most common chromosomal change in mammals. Robertsonian translocations are particularly rampant in the house mouse, Mus musculus domesticus, where they exhibit meiotic drive and create reproductive isolation. Recent progress has been made in understanding how Robertsonian chromosomes form in the human genome, highlighting some of the fundamental principles of how and why these types of fusion events occur so frequently. Consequences of these fusions include infertility and Down's syndrome. In this Hypothesis, I postulate that the conditions that allow these fusions to form are threefold: (1) sequence homology on non-homologous chromosomes, often in the form of repetitive DNA; (2) recombination initiation during meiosis; and (3) physical proximity of the homologous sequences in three-dimensional space. This Hypothesis highlights the latest progress in understanding human Robertsonian translocations within the context of the broader literature on Robertsonian chromosomes.

Chromosomal Abnormalities of Interest in Turner Syndrome: An Update

Turner syndrome (TS) is caused by the total or partial loss of the second sex chromosome; it occurs in 1 every 2,500-3,000 live births. The clinical phenotype is highly variable and includes short stature and gonadal dysgenesis. In 1959, the chromosomal origin of the syndrome was recognized; patients had 45 chromosomes with a single X chromosome. TS presents numerical and structural abnormalities in the sex chromosomes, interestingly only 40% have a 45, X karyotype. The rest of the chromosomal abnormalities include mosaics, deletions of the short and long arms of the X chromosome, rings, and isochromosomes. Despite multiple studies to establish a relationship between the clinical characteristics and the different chromosomal variants in TS, a clear association cannot yet be established. Currently, different mechanisms involved in the phenotype have been explored. This review focuses to analyze the different chromosomal abnormalities and phenotypes in TS and discusses the possible mechanisms that lead to these abnormalities.

Dermatologic care of patients with differences of sex development

Background

Differences of sex development (DSD or disorders of sex development) are uncommon congenital conditions, characterized by atypical development of chromosomal, gonadal, or anatomic sex.

Objective

Dermatologic care is an important component of the multidisciplinary care needed for individuals with DSD. This article discusses the most common primary dermatologic manifestations of DSD in addition to the cutaneous manifestations of hormonal and surgical therapies in individuals with DSD.

Data sources

Published articles including case series and case reports on PubMed.

Study selections

Selection was conducted by examining existing literature with a team of multidisciplinary specialists.

Methods

Narrative review.

Limitations

This article was not conducted as a systematic review.

Results

In Klinefelter syndrome, refractory leg ulcers and incontinentia pigmenti have been described. Turner syndrome is associated with lymphatic malformations, halo nevi, dermatitis, and psoriasis. Virilization can be seen in some forms of congenital adrenal hyperplasia, where acne and hirsutism are common.

Conclusion

Dermatologists should consider teratogenic risk for treatments of skin conditions in DSD depending on pregnancy potential. Testosterone replacement, commonly used for Klinefelter syndrome, androgen insensitivity syndrome, 5-alpha reductase deficiency, gonadal dysgenesis, or ovotesticular DSD, may cause acne.

The p-Arms of Human Acrocentric Chromosomes Play by a Different Set of Rules

The p-arms of the five human acrocentric chromosomes bear nucleolar organizer regions (NORs) comprising ribosomal gene (rDNA) repeats that are organized in a homogeneous tandem array and transcribed in a telomere-to-centromere direction. Precursor ribosomal RNA transcripts are processed and assembled into ribosomal subunits, the nucleolus being the physical manifestation of this process. I review current understanding of nucleolar chromosome biology and describe current exploration into a role for the NOR chromosomal context. Full DNA sequences for acrocentric p-arms are now emerging, aided by the current revolution in long-read sequencing and genome assembly. Acrocentric p-arms vary from 10.1 to 16.7 Mb, accounting for ∼2.2% of the genome. Bordering rDNA arrays, distal junctions, and proximal junctions are shared among the p-arms, with distal junctions showing evidence of functionality. The remaining p-arm sequences comprise multiple satellite DNA classes and segmental duplications that facilitate recombination between heterologous chromosomes, which is likely also involved in Robertsonian translocations.

A Baby With Complete Androgen Insensitivity Syndrome and the Fortuitous Discovery of 45,X/46,XY Mosaicism

Disorders of sex development (DSD) are caused by defects in the complex sexual differentiation cascade, resulting in discordance among an individual's genetic, gonadal, and genital sexes. It affects one in 4,500 live births. A wide spectrum of genital phenotypes can be found depending on the underlying pathogenic mechanism and the developmental stage that is affected. We herein report a newborn with female external genitalia but palpable gonads at labia majora with normal testicular function and structure, which is typical of complete androgen insensitivity syndrome (CAIS). The genetic study revealed 45,X/46,XY mosaicism and c.2081A>C missense androgen receptor gene mutation, indicating the likelihood of co-existing CAIS. This case demonstrated the importance of correlating genital phenotype and the underlying pathogenic mechanism, to provide appropriate management of DSD. Important considerations on managing the gonads about the risks of gonadal malignancies are also discussed.

Recombination between heterologous human acrocentric chromosomes

The short arms of the human acrocentric chromosomes 13, 14, 15, 21 and 22 (SAACs) share large homologous regions, including ribosomal DNA repeats and extended segmental duplications1,2. Although the resolution of these regions in the first complete assembly of a human genome-the Telomere-to-Telomere Consortium's CHM13 assembly (T2T-CHM13)-provided a model of their homology3, it remained unclear whether these patterns were ancestral or maintained by ongoing recombination exchange. Here we show that acrocentric chromosomes contain pseudo-homologous regions (PHRs) indicative of recombination between non-homologous sequences. Utilizing an all-to-all comparison of the human pangenome from the Human Pangenome Reference Consortium4 (HPRC), we find that contigs from all of the SAACs form a community. A variation graph5 constructed from centromere-spanning acrocentric contigs indicates the presence of regions in which most contigs appear nearly identical between heterologous acrocentric chromosomes in T2T-CHM13. Except on chromosome 15, we observe faster decay of linkage disequilibrium in the pseudo-homologous regions than in the corresponding short and long arms, indicating higher rates of recombination6,7. The pseudo-homologous regions include sequences that have previously been shown to lie at the breakpoint of Robertsonian translocations8, and their arrangement is compatible with crossover in inverted duplications on chromosomes 13, 14 and 21. The ubiquity of signals of recombination between heterologous acrocentric chromosomes seen in the HPRC draft pangenome suggests that these shared sequences form the basis for recurrent Robertsonian translocations, providing sequence and population-based confirmation of hypotheses first developed from cytogenetic studies 50 years ago9.

Turner syndrome: fertility counselling in childhood and through the reproductive lifespan

PURPOSE OF REVIEW

The potential for fertility in Turner syndrome has improved in recent years. Understanding of associated risks and approaches is important for the care of girls and women with this condition. This review focuses on reproductive health, fertility options and appropriate counselling for women with Turner syndrome and their families.

RECENT FINDINGS

Women with Turner syndrome have rapidly declining ovarian function beginning in utero . Therefore, counselling regarding fertility concerns should begin at a young age and involve discussion of options, including ovarian tissue cryopreservation, oocyte preservation and use of nonautologous oocytes. Clinical guidance on fertility management and pregnancy risk assessment based on karyotype, associated comorbidities and fertility is still not fully data driven. Realistic expectations regarding reproductive options and associated outcomes as well as the need for multidisciplinary follow-up during pregnancy are crucial to the ethical and safe care of these patients.

SUMMARY

Fertility care in women with Turner syndrome is evolving as current management techniques improve and new approaches are validated. Early counselling and active management of fertility preservation is critical to ensure positive and well tolerated reproductive outcomes.

The Changing Face of Turner Syndrome

Turner syndrome (TS) is a condition in females missing the second sex chromosome (45,X) or parts thereof. It is considered a rare genetic condition and is associated with a wide range of clinical stigmata, such as short stature, ovarian dysgenesis, delayed puberty and infertility, congenital malformations, endocrine disorders, including a range of autoimmune conditions and type 2 diabetes, and neurocognitive deficits. Morbidity and mortality are clearly increased compared with the general population and the average age at diagnosis is quite delayed. During recent years it has become clear that a multidisciplinary approach is necessary toward the patient with TS. A number of clinical advances has been implemented, and these are reviewed. Our understanding of the genomic architecture of TS is advancing rapidly, and these latest developments are reviewed and discussed. Several candidate genes, genomic pathways and mechanisms, including an altered transcriptome and epigenome, are also presented.

Non-invasive Prenatal Testing in Pregnancies Following Assisted Reproduction

In the decade since non-invasive prenatal testing (NIPT) was first implemented as a prenatal screening tool, it has gained recognition for its sensitivity and specificity in the detection of common aneuploidies. This review mainly focuses on the emerging role of NIPT in pregnancies following assisted reproductive technology (ART) in the light of current evidence and recommendations. It also deals with the challenges, shortcomings and interpretational difficulties related to NIPT in ART pregnancies, with particular emphasis on twin and vanishing twin pregnancies, which are widely regarded as the Achilles' heel of most pre-natal screening platforms. Future directions for exploration towards improving the performance and extending the scope of NIPT are also addressed.

Are ovarian responses and the number of transferable embryos different in females and partners of male balanced translocation carriers?

PURPOSE

To compare ovarian response and the number of transferable embryos between women with balanced autosomal translocations and women whose partners carry the translocation (control group). To investigate the predictive value of metaphase II (MII) oocyte number and biopsied embryo number for gaining at lowest one transferable embryo.

DESIGN

We retrospectively analyzed 1942 preimplantation genetic testing for structural rearrangements (PGT-SR) cycles of 1505 balanced autosomal translocation couples over 8 years. All cycles were divided into two subgroups: Robertsonian and reciprocal translocations (ROBT and ReBT). Receiver operator characteristic (ROC) curves were plotted to ascertain a cutoff of MII oocytes and biopsied embryos as predictors of gaining at lowest one transferable embryo.

RESULT

There were no statistical differences in baseline features or ovarian response indicators regarding the number of retrieved/MII oocytes, E2 level on the day of HCG, and ovarian sensitivity index (OSI) between women with balanced autosomal translocations and control group (P > 0.05). A decreased number of transferable embryos were found in women with balanced autosomal translocations regardless of the type of translocation. The cutoff values for gaining at lowest one transferable embryo are 12.5 MII oocytes and 4.5 biopsied embryos, respectively.

CONCLUSION

Women with balanced autosomal translocations have a normal ovarian response, but fewer transferable embryos, meaning that higher gonadotropin (Gn) doses may be required to increase transferable embryos. When fewer than 12.5 MII oocytes or 4.5 blastocysts are obtained in a PGT-SR cycle, couples should be notified that the likelihood of gaining a transferable embryo is low.

Short arms of human acrocentric chromosomes and the completion of the human genome sequence

The complete, ungapped sequence of the short arms of human acrocentric chromosomes (SAACs) is still unknown almost 20 years after the near completion of the Human Genome Project. Yet these short arms of Chromosomes 13, 14, 15, 21, and 22 contain the ribosomal DNA (rDNA) genes, which are of paramount importance for human biology. The sequences of SAACs show an extensive variation in the copy number of the various repetitive elements, the full extent of which is currently unknown. In addition, the full spectrum of repeated sequences, their organization, and the low copy number functional elements are also unknown. The Telomere-to-Telomere (T2T) Project using mainly long-read sequence technology has recently completed the assembly of the genome from a hydatidiform mole, CHM13, and has thus established a baseline reference for further studies on the organization, variation, functional annotation, and impact in human disorders of all the previously unknown genomic segments, including the SAACs. The publication of the initial results of the T2T Project will update and improve the reference genome for a better understanding of the evolution and function of the human genome.

Optical Genome Mapping in Routine Human Genetic Diagnostics-Its Advantages and Limitations

In recent years, optical genome mapping (OGM) has developed into a highly promising method of detecting large-scale structural variants in human genomes. It is capable of detecting structural variants considered difficult to detect by other current methods. Hence, it promises to be feasible as a first-line diagnostic tool, permitting insight into a new realm of previously unknown variants. However, due to its novelty, little experience with OGM is available to infer best practices for its application or to clarify which features cannot be detected. In this study, we used the Saphyr system (Bionano Genomics, San Diego, CA, USA), to explore its capabilities in human genetic diagnostics. To this end, we tested 14 DNA samples to confirm a total of 14 different structural or numerical chromosomal variants originally detected by other means, namely, deletions, duplications, inversions, trisomies, and a translocation. Overall, 12 variants could be confirmed; one deletion and one inversion could not. The prerequisites for detection of similar variants were explored by reviewing the OGM data of 54 samples analyzed in our laboratory. Limitations, some owing to the novelty of the method and some inherent to it, were described. Finally, we tested the successful application of OGM in routine diagnostics and described some of the challenges that merit consideration when utilizing OGM as a diagnostic tool.

Criteria to evaluate patterns of segmental and complete aneuploidies in preimplantation genetic testing for aneuploidy results suggestive of an inherited balanced translocation or inversion

Objective

To define criteria for determining when preimplantation genetic testing for aneuploidy (PGT-A) results are suggestive of a potential balanced chromosomal rearrangement in the egg or sperm source and warrant karyotyping.

Design

Performance evaluation of criteria developed to assess PGT-A results for patterns of imbalances suggestive of a balanced chromosomal rearrangement in the egg or sperm source.

Setting

A single PGT-A laboratory and multiple in vitro fertilization centers.

Patients

Reproductive couples who underwent routine PGT-A testing.

Interventions

Karyotyping of reproductive couples for whom patterns of imbalances observed in PGT-A results suggested a balanced chromosomal rearrangement in the egg or sperm source.

Main Outcome Measures

Correct or incorrect flagging of predicted translocation in either the egg or sperm source based on chromosome analysis.

Results

Proposed criteria correctly predicted a balanced reciprocal translocation in 97% of cases (n = 33), a (13;14) Robertsonian translocation in all cases (n = 3), and an inversion in all cases (n = 2). Other criteria evaluated were determined to be ineffective because of relatively low occurrences that met the criteria and/or low predictive value.

Conclusions

Our results showed that the proposed criteria were effective for evaluating patterns of imbalances observed in PGT-A results suggestive of a potential chromosomal rearrangement in the egg or sperm source. Our proposed criteria can be employed by clinicians in the in vitro fertilization setting in combination with a patient's reproductive history to identify PGT-A patients who are likely carriers of balanced chromosomal rearrangements.

Human Chromosome 18 and Acrocentrics: A Dangerous Liaison

The presence of thousands of repetitive sequences makes the centromere a fragile region subject to breakage. In this study we collected 31 cases of rearrangements of chromosome 18, of which 16 involved an acrocentric chromosome, during genetic screening done in three centers. We noticed a significant enrichment of reciprocal translocations between the centromere of chromosome 18 and the centromeric or pericentromeric regions of the acrocentrics. We describe five cases with translocation between chromosome 18 and an acrocentric chromosome, and one case involving the common telomere regions of chromosomes 18p and 22p. In addition, we bring evidence to support the hypothesis that chromosome 18 preferentially recombines with acrocentrics: (i) the presence on 18p11.21 of segmental duplications highly homologous to acrocentrics, that can justify a NAHR mechanism; (ii) the observation by 2D-FISH of the behavior of the centromeric regions of 18 respect to the centromeric regions of acrocentrics in the nuclei of normal subjects; (iii) the contact analysis among these regions on published Hi-C data from the human lymphoblastoid cell line (GM12878).

Blastocyst conversion rate and ploidy in patients with structural rearrangements

OBJECTIVE

The primary objective of this study was to test the hypotheses that compared to IVF cycles undergoing preimplantation genetic testing for aneuploidy (PGT-A) with or without testing for monogenic disorders (PGT-M), IVF cycles undergoing PGT for structural rearrangements (PGT-SR) will have (1) a poorer blastocyst conversion rate and (2) fewer usable blastocysts available for transfer. Secondarily, the study aimed to compare pregnancy outcomes among PGT groups.

PATIENTS

Retrospective cohort study including cycles started from January 1, 2012, to March 30, 2020, with the intent of pursuing PGT-A, PGT-A with PGT-M, and PGT-SR, with trophectoderm biopsy on days 5 or 6.

RESULTS

A total of 658 women underwent 902 cycles, including 607 PGT-A, 216 PGT-A&M, and 79 PGT-SR cycles. When compared with the blastocyst conversion rate for the PGT-A group (59.4%), and after adjustment for patient age, total number of mature oocytes, BMI, and ICSI, there were no significant differences for either the PGT-A&M (69.7%, aRR 1.03, 95% CI 0.96-1.10) or PGT-SR (63.2%, aRR1.04, 95% CI 0.96-1.13) groups. Compared to the PGT-A group, the proportion of usable blastocysts was statistically significantly lower in the PGT-SR group: 35.1% versus 24.4% (aRR 0.57, 95% CI 0.46-0.71) and the PGT-A&M group: 35.1% versus 31.5% (aRR 0.68, 95% CI 0.58-0.81). Implantation, pregnancy, and miscarriage rates were equivalent for all groups.

CONCLUSION

Patients with structural rearrangements have similar blastocyst development but significantly fewer usable blastocysts available for transfer compared to PGT-A testers. Nevertheless, with the transfer of a usable embryo, PGT-SR testers perform as well as those testing for PGT-A.

Prevalence and Phenotypic Impact of Robertsonian Translocations

Robertsonian translocations (RTs) result from fusion of 2 acrocentric chromosomes (e.g., 13, 14, 15, 21, 22) and consequential losses of segments of the p arms containing 47S rDNA clusters and transcription factor binding sites. Depending on the position of the breakpoints, the size of these losses vary considerably between types of RTs. The prevalence of RTs in the general population is estimated to be around 1 per 800 individuals, making RTs the most common chromosomal rearrangement in healthy individuals. Based on their prevalence, RTs are classified as "common," rob(13;14) and rob(14;21), or "rare" (the 8 remaining nonhomologous combinations). Carriers of RTs are at an increased risk for offspring with chromosomal imbalances or with uniparental disomy. RTs are generally regarded as phenotypically neutral, although, due to RTs formation, 2 of the 10 ribosomal rDNA gene clusters, several long noncoding RNAs, and in the case of RTs involving chromosome 21, several mRNA encoding genes are lost. Nevertheless, recent evidence indicates that RTs may have a significant phenotypic impact. In particular, rob(13;14) carriers have a significantly elevated risk for breast cancer. While RTs are easily spotted by routine karyotyping, they may go unnoticed if only array-CGH and NextGen sequencing methods are applied. This review first discusses possible molecular mechanisms underlying the particularly high rates of RT formation and their incidence in the general population, and second, likely causes for the elevated cancer risk of some RTs will be examined.

Heritable human genome editing: Research progress, ethical considerations, and hurdles to clinical practice

Our genome at conception determines much of our health as an adult. Most human diseases have a heritable component and thus may be preventable through heritable genome editing. Preventing disease from the beginning of life before irreversible damage has occurred is an admirable goal, but the path to fruition remains unclear. Here, we review the significant scientific contributions to the field of human heritable genome editing, the unique ethical challenges that cannot be overlooked, and the hurdles that must be overcome prior to translating these technologies into clinical practice.

Assessment of the maxilla-mandible-nasion angle in normal and aneuploid foetuses in the first trimester of pregnancy

PURPOSE

This retrospective study aims to determine whether the maxilla-mandible-nasion (MMN) angle can be reliably measured in the first trimester, to describe normal ranges, and to determine if significant changes occur in foetuses with aneuploidies.

METHODS

The MMN angle was measured in stored 2D-ultrasound images of 200 normal fetal profiles between 11⁺⁰ and 13⁺⁶ weeks of gestation. Each image was analyzed by two observers at two independent time points. Bland-Altmann analysis was performed to evaluate the reliability of the measurements. Additionally, the MMN angle was measured on sonograms from 140 aneuploid foetuses.

RESULTS

The mean MMN angle in normal foetuses from 11 to 14 weeks of gestation was 15.4°. Reliability of the measurement was high when repeatedly measured by the same observer (ICC = 0.92 and 0.82) and between two observers (ICC = 0.77 and 0.63). Average MMN values in foetuses with trisomy 21, 13, and Turner syndrome were significantly higher than those measured in normal foetuses. The highest differences were observed in foetuses with trisomy 13. Among those, 62% had an MMN angle above the 95th percentile and 92% above the normal mean.

CONCLUSION

The MMN angle can be reliably measured in early pregnancy and is abnormal in about 60% of foetuses with trisomy 13.

Male pseudohermaphrodite with persistent Mullerian duct: A radiologist's and patient's dilemma alike

This case study highlights that how a disorder of sexual development when goes unnoticed at birth and unreported during childhood or adolescence can present with major problems and even complications in adulthood. Since our patient was young and in a childbearing age, he presented with bilateral undescended testes and orgasmic anejaculation when he first came to the hospital. Subsequently, having a normal 46XY karyotype but remnants of persistent Mullerian duct made him little confused about his identity. After giving him the confidence, that he was still a male and could lead the life he did previously, the explanation about future risk of malignancy in the intra-abdominal testes was another difficult task. Early detection and management of male pseudohermaphroditism with persistent Mullerian duct requires a co-ordinated approach of a team of endocrinologist, physician, surgeon and radiologist. Integrated imaging in the form of ultrasound, genitography and MRI is important in demonstrating the anatomy, classification, possible effects or congenital malformations in other organs, warning patients of any risk of neoplasia and guiding the clinician to plan other investigations, hormonal replacement or reconstruction surgery if required. Such a systemic approach that allays anxiety and gives psychological relief to the patient should be taken as it can deeply change the life of a person and their family.

How much, if anything, do we know about sperm chromosomes of Robertsonian translocation carriers?

In men with oligozoospermia, Robertsonian translocations (RobTs) are the most common type of autosomal aberrations. The most commonly occurring types are rob(13;14) and rob(14;21), and other types of RobTs are described as 'rare' cases. Based on molecular research, all RobTs can be broadly classified into Class 1 and Class 2. Class 1 translocations produce the same breakpoints within their RobT type, but Class 2 translocations are predicted to form during meiosis or mitosis through a variety of mechanisms, resulting in variation in the breakpoint locations. This review seeks to analyse the available data addressing the question of whether the molecular classification of RobTs into Classes 1 and 2 and/or the type of DD/GG/DG symmetry of the involved chromosomes is reflected in the efficiency of spermatogenesis. The lowest frequency value calculated for the rate of alternate segregants was found for rob(13;15) carriers (Class 2, symmetry DD) and the highest for rob(13;21) carriers (Class 2, DG symmetry). The aneuploidy values for the rare RobT (Class 2) and common rob(14;21) (Class 1) groups together exhibited similarities while differing from those for the common rob(13;14) (Class 1) group. Considering the division of RobT carriers into those with normozoospermia and those with oligoasthenozoospermia, it was found that the number of carriers with elevated levels of aneuploidy was unexpectedly quite similar and high (approx. 70%) in the two subgroups. The reason(s) that the same RobT does not always show a similar destructive effect on fertility was also pointed out.

The genetic cause of intellectual deficiency and/or congenital malformations in two parental reciprocal translocation carriers and implications for assisted reproduction

PURPOSE

To elucidate the genetic cause of intellectual deficiency and/or congenital malformations in two parental reciprocal translocation carriers and provide appropriate strategies of assisted reproductive therapy (ART).

MATERIALS AND METHODS

Two similar couples having a child with global developmental delay/intellectual disability symptoms attended the Reproductive and Genetic Hospital of CITIC-Xiangya (Changsha, China) in 2017 and 2019, respectively, in order to determine the cause(s) of the conditions affecting their child and to seek ART to have a healthy baby. Both of the healthy couples were not of consanguineous marriage, denied exposure to toxicants, and had no adverse life history. This study was approved by the Institutional Ethics Committee of the Reproductive & Genetic Hospital of CITIC-Xiangya, and written informed consent was obtained from the parents. Genetic diagnoses were performed by karyotype analysis, breakpoint mapping analysis of chromosomal translocation(s), single-nucleotide polymorphism (SNP) microarray analysis, and whole-exome sequencing (WES) for the two children and different appropriate reproductive strategies were performed in the two families.

RESULTS

Karyotype analysis revealed that both patients carried parental reciprocal translocations [46,XY,t(7;16)(p13;q24)pat and 46,XY,t(13;17)(q12.3;p11.2)pat, respectively]. Follow-up breakpoint mapping analysis showed no interruption of associated genes, and SNP microarray analysis identified no significant copy number variations (CNVs) in the two patients. Moreover, WES results revealed that patients 1 and 2 harbored candidate compound heterozygous mutations of MCOLN1 [c.195G>C (p.K65N) and c.1061G>A (p.W354*)] and MCPH1 [c.877A>G (p.S293G) and c.1869_1870delAT (p.C624*)], respectively, that were inherited from their parents and not previously reported. Furthermore, the parents of patient 1 obtained 10 embryos during ART cycle, and an embryo of normal karyotype and non-carrier of observed MCOLN1 mutations according to preimplantation genetic testing for structural rearrangement and monogenic defect was successfully transferred, resulting in the birth of a healthy boy. The parents of patient 2 chose to undergo ART with donor sperm to reduce the risk of recurrence.

CONCLUSIONS

Systematic genetic diagnosis of two carriers of inherited chromosomal translocations accompanied by clinical phenotypes revealed their cause of disease, which was critical for genetic counseling and further ART for these families.

European academy of andrology guidelines on Klinefelter Syndrome Endorsing Organization: European Society of Endocrinology

BACKGROUND

Knowledge about Klinefelter syndrome (KS) has increased substantially since its first description almost 80 years ago. A variety of treatment options concerning the spectrum of symptoms associated with KS exists, also regarding aspects beyond testicular dysfunction. Nevertheless, the diagnostic rate is still low in relation to prevalence and no international guidelines are available for KS.

OBJECTIVE

To create the first European Academy of Andrology (EAA) guidelines on KS.

METHODS

An expert group of academicians appointed by the EAA generated a consensus guideline according to the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) system.

RESULTS

Clinical features are highly variable among patients with KS, although common characteristics are severely attenuated spermatogenesis and Leydig cell impairment, resulting in azoospermia and hypergonadotropic hypogonadism. In addition, various manifestations of neurocognitive and psychosocial phenotypes have been described as well as an increased prevalence of adverse cardiovascular, metabolic and bone-related conditions which might explain the increased morbidity/mortality in KS. Moreover, compared to the general male population, a higher prevalence of dental, coagulation and autoimmune disorders is likely to exist in patients with KS. Both genetic and epigenetic effects due to the supernumerary X chromosome as well as testosterone deficiency contribute to this pathological pattern. The majority of patients with KS is diagnosed during adulthood, but symptoms can already become obvious during infancy, childhood or adolescence. The paediatric and juvenile patients with KS require specific attention regarding their development and fertility.

CONCLUSION

These guidelines provide recommendations and suggestions to care for patients with KS in various developmental stages ranging from childhood and adolescence to adulthood. This advice is based on recent research data and respective evaluations as well as validations performed by a group of experts.

Barriers in access to healthcare services for individuals with disorders of sex differentiation in Bangladesh: an analysis of regional representative cross-sectional data

Background

Worldwide people in disorder of sex development (DSD) faces multiple barriers while seeking their social rights, particularly healthcare services. We aimed to explore the healthcare opportunities available to them, using patterns of healthcare utilization and difficulties faced by DSD population in accessing healthcare services in Bangladesh.

Methods

Data from a total of 945 DSD population and 71 medical staff were analyzed, collected from three major divisions (Dhaka, Chittagong, and Rajshahi) in Bangladesh during the period of January to December of 2017. A structured questionnaire was used to collect data via face-to-face interviews. Descriptive statistic was used to determine the frequencies of the visit by the DSD population in healthcare facilities as well as to analyze difficulties experienced by the DSD population in getting healthcare services. Multivariate regression analysis was used to explore the association between perceived barriers in getting healthcare services and failures of the DSD population to receive the healthcare services.

Results

Present data revealed that around 80% of DSD population sought healthcare services from government healthcare facilities, where the overall success rate in getting healthcare services was less than 50%. The DSD population reported a number of reasons for failures in getting healthcare services, including non-friendly interaction by non-clinical hospital’s staff, non-friendly interaction by physicians, public fright as general people do not want to mingle with a DSD person, undesirable excess public interest in DSD individuals, and limitation of the treatment opportunities of hospitals to merely male or female patients. Among the stated reasons, the most frequently reported reason was non-friendly interaction by physicians (50.27%), followed by undesirable excess public interest in DSD individuals (50.16%).

Conclusion

DSD population in Bangladesh have limited access to healthcare facilities and facing multiple barriers to get healthcare services. Initiatives from the government and social organizations are important to ensure their access to healthcare services.

Monochorionic diamniotic twins of discordant external genitalia with 45,X/46,XY mosaicism

Background

Monozygotic twins with 45,X/46,XY mosaicism, discordant for phenotypic sex, are extremely rare.

Methods

This report describes the clinical findings of a rare case of 45,X/46,XY mosaicism in monozygotic twins with different external genitalia. Single nucleotide polymorphism (SNP) array analysis, performed by collecting DNA from each umbilical cord, showed identical SNPs in the autosomal chromosomes of both fetuses.

Results

Chorionic villus sampling of a 37‐year‐old primigravida carrying monozygotic twins revealed a 45,X/46,XY karyotype. Autopsy of the aborted fetuses revealed a penis and testes on one fetus and a vagina, uterus, and ovaries in the other fetus––which also had severe cystic hygroma. Cell counting using fluorescence in situ hybridization with XY probes (XY‐FISH) showed 20% and 80% abundance of 45,X cells in the internal genitalia, liver, heart, lung, adrenal gland, bone marrow, and spine of the male and female fetuses, respectively.

Conclusion

These results indicated that the fetuses were genetically monozygotic twins and their different degrees of mosaicism may have resulted in different genital phenotypes.

Early neurodevelopmental and medical profile in children with sex chromosome trisomies: Background for the prospective eXtraordinarY babies study to identify early risk factors and targets for intervention

Sex chromosome trisomies (SCT), including Klinefelter syndrome/XXY, Trisomy X, and XYY syndrome, occur in 1 of every 500 births. The past decades of research have resulted in a broadening of known associated medical comorbidities as well as advances in psychological research. This review summarizes what is known about early neurodevelopmental, behavioral, and medical manifestations in young children with SCT. We focus on recent research and unanswered questions related to the risk for neurodevelopmental disorders that commonly present in the first years of life and discuss the medical and endocrine manifestations of SCT at this young age. The increasing rate of prenatal SCT diagnoses provides the opportunity to address gaps in the existing literature in a new birth cohort, leading to development of the eXtraordinarY Babies Study. This study aims to better describe and compare the natural history of SCT conditions, identify predictors of positive and negative outcomes in SCT, evaluate developmental and autism screening measures commonly used in primary care practices for the SCT population, and build a rich data set linked to a bank of biological samples for future study. Results from this study and ongoing international research efforts will inform evidence-based care and improve health and neurodevelopmental outcomes.

The epidemiology of sex chromosome abnormalities

Sex chromosome abnormalities (SCAs) are characterized by gain or loss of entire sex chromosomes or parts of sex chromosomes with the best-known syndromes being Turner syndrome, Klinefelter syndrome, 47,XXX syndrome, and 47,XYY syndrome. Since these syndromes were first described more than 60 years ago, several papers have reported on diseases and health related problems, neurocognitive deficits, and social challenges among affected persons. However, the generally increased comorbidity burden with specific comorbidity patterns within and across syndromes as well as early death of affected persons was not recognized until the last couple of decades, where population-based epidemiological studies were undertaken. Moreover, these epidemiological studies provided knowledge of an association between SCAs and a negatively reduced socioeconomic status in terms of education, income, retirement, cohabitation with a partner and parenthood. This review is on the aspects of epidemiology in Turner, Klinefelter, 47,XXX and 47,XYY syndrome.

Current survey of early childhood intervention services in infants and young children with sex chromosome aneuploidies

Sex chromosome aneuploidies (SCAs) are the most commonly occurring aneuploidies in children with a collective prevalence rate of 1 in 500 live births. Prior research has documented SCAs are associated with an increased risk for early expressive language and gross motor delays, learning disorders, ADHD, autism spectrum disorder, anxiety, and executive function problems. Although SCAs have been historically underdiagnosed in young children, recent advances in noninvasive prenatal testing have resulted in an increasing nationwide cohort of infants with confirmed diagnoses. Consequently, early childhood support systems must prepare for an influx of children with known risks for associated developmental delays and potential school problems. This national survey aimed to update our understanding of current early childhood intervention services for young children with SCA in the United States and to describe parent perspectives and priorities. Descriptive statistics, chi-square tests, and logistic regression models controlling for parent education revealed a majority of respondents reported receiving public early childhood intervention services with speech therapy as the most common service. There were significant differences in early childhood intervention services by timing of diagnosis (prenatal vs. postnatal), number of sex chromosomes (trisomy vs. tetra/pentasomy), and geographic location. Parents described interventions as desirable and effective yet also difficult to obtain due to issues with the SCA phenotype, lack of provider knowledge, and challenges navigating the intervention systems. Results support the need for enhanced provider training in SCAs, policy change for early childhood intervention qualification criteria for SCA conditions, and collaboration between medical and early childhood settings.

Gonadal dysfunction and beyond: Clinical challenges in children, adolescents, and adults with 47,XXY Klinefelter syndrome

Klinefelter syndrome (KS) is the most frequent sex chromosomal aneuploidy. The karyotype 47,XXY originates from either paternal or maternal meiotic nondisjunction during gametogenesis. KS males are very likely to exhibit marked gonadal dysfunctions, presenting both in severely attenuated spermatogenesis as well as hypergonadotropic hypogonadism. In addition, neurocognitive and psychosocial impairments, as well as cardiovascular, metabolic and bone disorders are often found in KS and might explain for an increased morbidity/mortality. All conditions in KS are likely to be induced by both gene overdosage effects resulting from supernumerary X-chromosomal genes as well as testosterone deficiency. Notwithstanding, the clinical features are highly variable between KS men. Symptoms can become obvious at infancy, childhood, or adolescence. However, the majority of KS subjects is diagnosed during adulthood. KS adolescents require specific attention regarding pubertal development, in order to exploit their remaining fertility potential and allow for timely and tailored testosterone replacement. The chances for sperm retrieval might decline with age and could be hampered by testosterone replacement; therefore, cryostorage of spermatozoa is an option during adolescence, before the decompensation of endocrine and exocrine testicular functions becomes more overt. Sperm from semen or surgically retrieved, in combination with intracytoplasmic sperm injection enables KS males to become biological fathers of healthy children. The aim of this article is to present the current knowledge on KS, to guide clinical care and to highlight research needs.

Instability of Short Arm of Acrocentric Chromosomes: Lesson from Non-Acrocentric Satellited Chromosomes. Report of 24 Unrelated Cases

Satellited non-acrocentric autosomal chromosomes (ps–qs-chromosomes) are the result of an interchange between sub- or telomeric regions of autosomes and the p arm of acrocentrics. The sequence homology at the rearrangement breakpoints appears to be, among others, the most frequent mechanism generating these variant chromosomes. The unbalanced carriers of this type of translocation may or may not display phenotypic abnormalities. With the aim to understand the causative mechanism, we revised all the ps–qs-chromosomes identified in five medical genetics laboratories, which used the same procedures for karyotype analysis, reporting 24 unrelated cases involving eight chromosomes. In conclusion, we observed three different scenarios: true translocation, benign variant and complex rearrangement. The detection of translocation partners is essential to evaluate possible euchromatic unbalances and to infer their effect on phenotype. Moreover, we emphasize the importance to perform both, molecular and conventional cytogenetics methods, to better understand the behavior of our genome.

Meiotic Chromosome Contacts as a Plausible Prelude for Robertsonian Translocations

Robertsonian translocations are common chromosomal alterations. Chromosome variability affects human health and natural evolution. Despite the significance of such mutations, no mechanisms explaining the emergence of such translocations have yet been demonstrated. Several models have explored possible changes in interphase nuclei. Evidence for non-homologous chromosomes end joining in meiosis is scarce, and is often limited to uncovering mechanisms in damaged cells only. This study presents a primarily qualitative analysis of contacts of non-homologous chromosomes by short arms, during meiotic prophase I in the mole vole, Ellobius alaicus, a species with a variable karyotype, due to Robertsonian translocations. Immunocytochemical staining of spermatocytes demonstrated the presence of four contact types for non-homologous chromosomes in meiotic prophase I: (1) proximity, (2) touching, (3) anchoring/tethering, and (4) fusion. Our results suggest distinct mechanisms for chromosomal interactions in meiosis. Thus, we propose to change the translocation mechanism model from ‘contact first’ to ‘contact first in meiosis’.

Disorders of Sex Development: A 10 Years Experience with 73 Cases from the Kashmir Valley

PURPOSE

To present the clinical data, investigative profile, and management of patients with disorders of sex development (DSD) from the endocrine unit of a tertiary care university hospital.

MATERIALS AND METHODS

This retrospective study included 73 cases of DSD, evaluated and managed at Department of Endocrinology, Sher-i-Kashmir Institute of Medical Sciences, Srinagar, Kashmir, over a period of 10 years from September 2008 to August 2018.

RESULTS

Twenty-nine patients (39.7%) had 46 XY DSD and twenty-nine patients (39.7%) had 46 XX. Sex chromosome DSD was diagnosed in 15 (20.5%) patients. Of 29 patients with 46 XY DSD, 17 (58.6%) had 5α-reductase type-2 deficiency (5α-RD) and 6 (20.7%) had complete androgen insensitivity syndrome. In our patients with 5α-RD, the history of consanguinity was documented in nine (52.9%) patients. Two patients had testosterone biosynthetic defect and one patient had partial androgen insensitivity syndrome. Of 29 patients with 46 XX DSD, 16 (55.1%) had congenital adrenal hyperplasia (CAH). Of 15 patients with sex chromosome DSD, 7 patients had Turner's syndrome, 7 had Klinefelter's syndrome, and 1 patient had mixed gonadal dysgenesis.

CONCLUSION

In our study, equal number of patients had 46 XY DSD and 46 XX DSD. We are for the first time reporting from India that the most common cause of 46 XY DSD is 5α-RD, whereas CAH is the most common cause of 46 XX DSD as reported previously.

Evaluation of sexual function and micro- testicular sperm extraction in men with mosaic Turner syndrome

Background

Men with mosaic Turner syndrome (TS) having karyotype 45,X/46,XY are infrequently seen. Their sexual function and fertility potential are not well documented. We describe the sexual function and outcomes of sperm extraction in 5 such men who were evaluated between 2008 and 2017.

Methods

Five phenotypic men diagnosed to have mosaic TS underwent detailed physical examination, semen analysis and evaluation of follicle-stimulating hormone, luteinizing hormone, prolactin and total testosterone. Blood, testis, oral mucosa and skin fluorescence in situ hybridization (FISH) analyses were done for evaluating the karyotype. Genomic DNA was extracted from peripheral blood for molecular analysis of azoospermic factor (AzF) deletions. Sexual function was assessed using the International Index of Erectile Function-5 (IIEF-5). One patient also underwent micro-testicular sperm extraction (micro-TESE) and intracytoplasmic sperm injection (ICSI).

Results

All 5 men had a mosaic 45,X/46,XY genotype and the sex-determining region (SRY) was positive in DYZ1- negative cells. None had a deletion in the AzF a, b or c regions. Sperm was detected in 3 patients through micro-TESE but ICSI could be done in only 1 patient. No embryo development was identified in time lapse (Embryoscope©) follow-up. It was observed that the rate of 46,XY was particularly high in gonadal tissues in the mosaic structure in patients detected to have sperms.

Conclusion

Patients with TS having 45,X/46,XY, SRY( + ), with no AzF deletions, and a high percentage of 46,XY in the peripheral blood, especially in gonadal tissues, could have a healthy sexual life and possibly father a child through in vitro fertilization or ICSI upon detection of sperms with micro-TESE.

The Frequency and Spectrum of Chromosomal Translocations in a Cohort of Sri Lankans

Translocations are the most common type of structural chromosomal abnormalities. Unbalanced translocations are usually found in children who present with congenital abnormalities, developmental delay, or intellectual disability. Balanced translocations are usually found in adults who frequently present with reproductive failure; either subfertility, or recurrent pregnancy loss. Herein, we report the spectrum and frequency of translocations in a Sri Lankan cohort. A database of patients undergoing cytogenetic testing was maintained prospectively from January 2007 to December 2016 and analyzed, retrospectively. A total of 15,864 individuals were tested. Among them, 277 (1.7%) had translocations. There were 142 (51.3%) unbalanced translocations and 135 (48.7%) balanced translocations. Majority (160; 57.8%) were Robertsonian translocations. There were 145 (52.3%) children and adolescents aged less than 18 years with translocations, and 142 (97.9%) were unbalanced translocations. Majority [138 (95.2%)] were referred due to congenital abnormalities, developmental delay, or intellectual disability, and 91 were children with translocation Down syndrome. All adults aged 18 years or above (132) had balanced translocations. Subfertility and recurrent pregnancy loss [84 (63.6%)] and offspring(s) with congenital abnormalities [48 (36.4%)] were the most common indications in this group. Majority (68.2%) in this group were females with reciprocal translocations (55.3%). Chromosomes 21, 14, and 13 were the most commonly involved with rob(14q21q) [72 (26%)], rob(21q21q) [30 (13.7%)], and rob(13q14q) [34 (12.3%)] accounting for 52% of the translocations. Chromosomes 1, 8, 11, and 18 were most commonly involved in reciprocal translocations. The observed high frequency of chromosomal translocations in our cohort highlights the importance of undertaking cytogenetic evaluation and providing appropriate genetic counseling for individuals with the phenotypes associated with these translocations.

Prevalence of XXY karyotypes in human blastocysts: multicentre data from 7549 trophectoderm biopsies obtained during preimplantation genetic testing cycles in IVF

STUDY QUESTION

Which is the prevalence of a 47,XXY karyotype in human blastocysts biopsied during preimplantation genetic testing for aneuploidies (PGT-A) cycles?

SUMMARY ANSWER

The prevalence of a 47,XXY karyotype amongst male blastocysts without autosomal aneuploides is ~1%.

WHAT IS KNOWN ALREADY

The prevalence of Klinefelter syndrome is estimated as 0.1-0.2% in male newborns. However, the KS phenotype is extremely variable and there are men with a 47,XXY karyotype and less evident signs, who may go undetected. No risk factor for the 47,XXY karyotype in products of conception has been yet clearly defined, and no data are available regarding the prevalence of this karyotype among human preimplantation embryos.

STUDY DESIGN, SIZE, DURATION

This multicentre cohort study involved 7549 blastocysts obtained during 2826 PGT-A cycles performed between April 2013 and September 2017 at six IVF clinics in Italy.

PARTICIPANTS/MATERIALS, SETTING, METHODS

During 2826 PGT-A cycles, 7549 blastocysts underwent trophectoderm biopsy and quantitative-PCR-based comprehensive chromosomal testing to predict the karyotype of the corresponding embryos. The results were also presented according to ranges of maternal and paternal age at oocyte retrieval as well as sperm factor and blastocyst quality. Univariate and multivariate logistic regression analyses were conducted to investigate the correlation of possible confounding factors with the prevalence of 47,XXY karyotype.

MAIN RESULTS, THE ROLE OF CHANCE

Overall, 62 blastocysts were 47,XXY or had an XXY karyotype associated with autosomal aneuploidies. After exclusion of the latter, the prevalence of a 47,XXY karyotype among male blastocysts without autosomal aneuploidies was 0.9% (n = 17/1794). A significant correlation was only found for maternal age and blastocyst quality (OR: 1.20, 95% CI: 1.01-1.42; P = 0.04 and OR: 1.6, 95% CI: 1.13-2.45; P = 0.01).

LIMITATIONS, REASONS FOR CAUTION

These retrospective data have been produced based on a population of infertile couples undergoing IVF and PGT-A, and the women were mainly of advanced maternal age. Moreover, the qPCR technique is validated only to detect full-chromosome uniform aneuploidies in trophectoderm biopsies.

WIDER IMPLICATIONS OF THE FINDINGS

The 0.9% prevalence of the 47,XXY karyotype among male blastocysts, when compared with the 0.1-0.2% prevalence reported in the prenatal and postnatal periods, suggests four possible scenarios that require further investigations: (i) the latter prevalence is underestimated; (ii) 47,XXY blastocysts result in a lower implantation rate than euploid embryos (estimated to be ≈50%); (iii) 47,XXY blastocysts result in a higher early miscarriage rate than euploid embryos (estimated to be ≈10%); or (iv) infertile patients of advanced maternal age and referred to IVF/PGT-A produce a higher rate of 47,XXY blastocysts.

STUDY FUNDING/COMPETING INTEREST(S)

None.

TRIAL REGISTRATION NUMBER

N/A.

Mortality and Cancer Incidence in Carriers of Balanced Robertsonian Translocations: A National Cohort Study

A balanced robertsonian translocation (rob) results from fusion of 2 acrocentric chromosomes. Carriers are phenotypically normal and are often diagnosed because of recurrent miscarriages, infertility, or aneuploid offspring. Mortality and site-specific cancer risks in carriers have not been prospectively investigated. We followed 1,987 carriers diagnosed in Great Britain for deaths and cancer risk, over an average of 24.1 years. Standardized mortality and incidence ratios were calculated comparing the number of observed events against population rates. Overall mortality was higher for carriers diagnosed before age 15 years (standardized mortality ratio (SMR) = 2.00, 95% confidence interval (CI): 1.09, 3.35), similar for those diagnosed aged 15–44 years (SMR = 1.06, 95% CI: 0.86–1.28), and lower for those diagnosed aged 45–84 years (SMR = 0.81, 95% CI: 0.68, 0.95). Cancer incidence was higher for non-Hodgkin lymphoma (standardized incidence ratio (SIR) = 1.90, 95% CI: 1.01, 3.24) and childhood leukemia (SIR = 14.5, 95% CI: 1.75, 52.2), the latter particularly in rob(15;21) carriers (SIR = 447.8, 95% CI: 11.3, 2,495). Rob(13;14) carriers had a higher breast cancer risk (SIR = 1.58, 95% CI: 1.12, 2.15). Mortality risks relative to the population in diagnosed carriers depend on age at cytogenetic diagnosis, possibly reflecting age-specific cytogenetic referral reasons. Carriers might be at greater risk of childhood leukemia and non-Hodgkin lymphoma and those diagnosed with rob(13;14) of breast cancer.

Changes in the cohort composition of turner syndrome and severe non-diagnosis of Klinefelter, 47,XXX and 47,XYY syndrome: a nationwide cohort study

Background

Knowledge on the prevalence of sex chromosome abnormalities (SCAs) is limited, and delayed diagnosis or non-diagnosis of SCAs are a continuous concern. We aimed to investigate change over time in incidence, prevalence and age at diagnosis among Turner syndrome (TS), Klinefelter syndrome (KS), Triple X syndrome (Triple X) and Double Y syndrome (Double Y).

Methods

This study is a nationwide cohort study in a public health care system. The Danish Cytogenetic Central Registry (DCCR) holds information on all karyotypes performed in Denmark since 1961. We identified all individuals in the DCCR with a relevant SCA during 1961–2014; TS: n = 1156; KS: n = 1235; Triple X: n = 197; and Double Y: n = 287. From Statistics Denmark, which holds an extensive collection of data on the Danish population, complete data concerning dates of death and migrations in and out of Denmark were retrieved for all individuals.

Results

The prevalence among newborns was as follows: TS: 59 per 100,000 females; KS: 57 per 100,000 males; Triple X: 11 per 100,000 females; and Double Y: 18 per 100,000 males. Compared with the expected number among newborns, all TS, 38% of KS, 13% of Triple X, and 18% of Double Y did eventually receive a diagnosis. The incidence of TS with other karyotypes than 45,X (P < 0.0001), KS (P = 0.02), and Double Y (P = 0.03) increased during the study period whereas the incidence of 45,X TS decreased (P = 0.0006). The incidence of Triple X was stable (P = 0.22).

Conclusions

The prevalence of TS is higher than previously identified, and the karyotypic composition of the TS population is changing. Non-diagnosis is extensive among KS, Triple X and Double Y, whereas all TS seem to become diagnosed. The diagnostic activity has increased among TS with other karyotypes than 45,X as well as among KS and Double Y.

A balanced translocation disrupting SCN5A in a family with Brugada syndrome and sudden cardiac death

BACKGROUND

Brugada syndrome (BrS) is a primary arrhythmia syndrome affecting 1 in 2000 of the general population. Genetic testing identifies pathogenic variants in the sodium voltage-gated channel α-subunit 5 gene (SCN5A) in up to 25% of familial BrS. Balanced translocations, which involve the exchange of the ends of 2 different chromosomes, are found in approximately 1 in 500 people. They usually are benign and only rarely are reported to cause arrhythmogenic disorders.

OBJECTIVE

The purpose of this study was to identify the genetic mechanism underlying a family with BrS, sick sinus syndrome, cardiac hypertrophy, sudden cardiac death, and multiple miscarriages.

METHODS

We clinically evaluated family members with an electrocardiogram, 2-dimensional echocardiogram, and provocation testing with ajmaline challenge. Cytogenetic testing included karyotype and fluorescent in situ hybridization (FISH) analysis. We performed gene panel, exome, and genome sequencing analysis.

RESULTS

Sequencing of 128 cardiac genes and exome sequencing of a family with BrS, sick sinus syndrome, cardiac hypertrophy, sudden cardiac death, and multiple miscarriages did not reveal a pathogenic variant. Karyotype and FISH analysis identified a balanced translocation breaking the SCN5A gene on chromosome 3 and the multiple chromosome maintenance 10 gene (MCM10) on chromosome 10 t(3;10)(p22.2;p13). We characterized both translocation breakpoint junctions using genome sequencing and found no regions of sequence homology.

CONCLUSION

A balanced translocation breaking SCN5A is a novel mechanism underlying disease in a family with BrS, sick sinus syndrome, cardiac hypertrophy, and sudden cardiac death. Genome sequencing can identify rare chromosomal aberrations causing inherited diseases that may otherwise be missed using gene panel and exome sequencing-based approaches.

Klinefelter Syndrome: Integrating Genetics, Neuropsychology, and Endocrinology

Although first identified over 70 years ago, Klinefelter syndrome (KS) continues to pose substantial diagnostic challenges, as many patients are still misdiagnosed, or remain undiagnosed. In fact, as few as 25% of patients with KS are accurately diagnosed and most of these diagnoses are not made until adulthood. Classic characteristics of KS include small testes, infertility, hypergonadothropic hypogonadism, and cognitive impairment. However, the pathophysiology behind KS is not well understood, although genetic effects are also thought to play a role. For example, recent developments in genetics and genomics point to a fundamental change in our understanding of KS, with global epigenetic and RNA expression changes playing a central role for the phenotype. KS is also associated with more general health markers, including higher morbidity and mortality rates and lower socioeconomic status (which likely affect both morbidity and mortality). In addition, hypogonadism is associated with greater risk of metabolic syndrome, type 2 diabetes, cardiovascular disease, breast cancer, and extragonadal germ cell tumors. Medical treatment typically focuses on testosterone replacement therapy (TRT), although the effects of this therapy have not been studied rigorously, and future studies need to evaluate the effects of TRT on metabolic risk and neurocognitive outcomes. This review presents a comprehensive interdisciplinary examination of recent developments in genetic, endocrine, and neurocognitive science, including the study of animal models. It provides a number of recommendations for improving the effectiveness of research and clinical practice, including neonatal KS screening programs, and a multidisciplinary approach to KS treatment from childhood until senescence.

Clinical aspects of 49 infertile males with 45,X/46,XY mosaicism karyotype: A case series

Disorders of sex development (DSD) are congenital abnormalities as an atypical development process in either gonadal or chromosomal structure. It is the cause of the abnormality in phenotype and characteristics. Chromosomal analysis plays an important role in the DSD determination. 45,X/46,XY mosaicism is a rare karyotype, and its prevalence is about 1.5 in 10,000 newborns. It affects the growth, hormonal balance, gonad development and histology. All data such as height, male general appearance, testis size and volume, external genitalia, spermogram and hormonal levels, testis pathology, Y chromosome microdeletion and karyotype, and assisted reproductive technology (ART) outcome were recorded based on patients profile and history. We investigated 64 infertile males with 45,X/46,XY mosaicism. Fifteen cases who had structural abnormalities in Y chromosome were excluded. From 49 available spermogram, 21 cases reported as azoospermic men, while 28 of them classified as nonazoospermic patients in which four of them displayed normal spermogram. According to hormonal evaluation, there were no significant differences between azoospermic and nonazoospermic groups. In azoospermia, only three couples underwent an ART cycle in which all of them failed. From 14 nonazoospermic cases who entered into the ART cycle, three cases experienced a successful pregnancy that one of the prosperous outcomes was twins. In 45,X/46,XY cases, both 45,X and 46,XY cell lines are seen. Various distributions of both cell lines can reflect a wide range of phenotypes that may be the most comprehensive evaluation in infertile males with 45,X/46,XY karyotype. It assumes that karyotyping as a main diagnostic test can enable us to find these rare cases.