Sex chromosome aneuploidies in 2020-The state of care and research in the world

The Use of Fluorescence In situ Hybridisation in the Diagnosis of Hidden Mosaicism in Egyptian Patients with Turner Syndrome

Background

Turner syndrome (TS) is the most common chromosomal abnormality in females. The diagnosis of TS is based on karyotyping of 30 blood lymphocytes. This technique does not rule out tissue mosaicism or low-grade mosaicism in the blood. Because of the associated risk of gonadoblastoma, mosaicism is especially important in case this involves a Y chromosome.

Aims

This study was set to determine the value of additional genetic studies such as fluorescent in situ hybridisation and the inclusion of buccal cells in search for mosaicism in TS patients.

Settings and Design

This cross-sectional, descriptive study was performed in Human Genetics Department, Medical Research Institute, Alexandria University.

Materials and Methods

Fluorescence in situ hybridisation technique was applied to lymphocyte cultures as well as buccal smears using centromeric probes for X and Y chromosomes. Genotype phenotype correlation was also evaluated.

Statistical Analysis Used

Descriptive study where categorical variables were described using number and percentage and continuous variables were described using mean and standard deviation.

Results

Fluorescence in situ hybridisation technique study detected hidden mosaicism in 60% of studied patients; 20% of patients had a cell line containing Y material, while 40% had variable degrees of X, XX mosaicism, and in the remaining 40% no second cell line was detected. Fluorescence in situ hybridisation study helped identify the origin of the marker to be Y in all patients. The introduction of an additional cell line helped in identifying mosaicism in patients with monosomy X. Virilisation signs were only observed among TS patients with Y cell line mosaicism. The clinical manifestations were more severe in patients with monosomy X than other mosaic cases.

Conclusions

Molecular cytogenetic investigation for all suspected cases of TS should be considered for appropriate treatment plan and genetic counselling.

How do genetic tests answer questions about neurodevelopmental differences? A sociological take

When it comes to neurodevelopmental differences, a genetic test result can provide compelling answers. However, it is not always clear what the relevant question is. If we want to understand the impact of a genetic diagnosis such as NGLY1 deficiency or the fragile X, trisomy X, or 22q11.2 deletion syndromes on people with neurodevelopmental differences, we must be mindful about what exactly a genetic test is supposed to tell us, where and for whom it matters, and which avenues for action it opens or forecloses. These are all moving targets. Specifically, I discuss the shifting ways a genetic test result can answer the following questions. What is this person's diagnosis? What symptoms and developmental differences are they likely to experience? What is the best way to approach their development, treatment, and care? Will they have a life worth living? When you unpack the sociological nuances of each question, the history behind them, and the uneven ways they are asked, the meanings of the answers change quite radically. I discuss the implications for social inequalities and urge experts and stakeholders to exercise agency when they interpret a genetic diagnosis. WHAT THIS PAPER ADDS: The questions a genetic test can answer depend on a range of social factors. Whether and how a genetic test result affects diagnosis, identity, prognosis, and treatment is a moving target. Genetics creates questions about a life worth living that it cannot answer alone. Stakeholders must choose the questions about neurodevelopmental differences that genetics should answer.

Parenthood among individuals with Turner syndrome: results of an online survey of attitudes towards pregnancy, adoption, and surrogacy

Choosing a route to parenthood can be a difficult decision for individuals with Turner syndrome, who must consider the unlikely possibility of spontaneous pregnancy, the potential need for assisted reproductive technology such as in vitro fertilization (IVF), and the risks of pregnancy-related complications. In addition, there are other options for parenthood, such as surrogacy and adoption. The perspectives of individuals with Turner syndrome regarding routes to parenthood have not been described in the literature, despite thorough investigation into the feasibility and safety of pregnancy in this population. We conducted a novel online survey of 226 individuals with Turner syndrome to assess their interest in parenthood, their perspectives on available routes to parenthood, and the factors that influence their decision-making. One-quarter of the respondents were already parents, including 54.5% who had achieved pregnancy and 45.5% who adopted. Of those who were not parents, 68.5% expressed a desire to become a parent. Overall, participants had the strongest interest in adoption as a route to parenthood. Interest in adoption was significantly associated with fear of pregnancy-related risks to their health and the health of a future child. Participants also reported interest in pregnancy and IVF. Interest in both pregnancy and IVF were significantly associated with a desire to experience pregnancy and to have a biological child. This study provides important insights into the perspective of individuals with Turner syndrome with respect to building a family and serves as a valuable counseling resource for clinicians facilitating patient decision-making about options for parenthood.

A Patient with Moderate Intellectual Disability and 49, XXXYY Karyotype

Klinefelter syndrome is a chromosomal disorder in which one extra X chromosome is present (47,XXY). Several other numeric variants of this syndrome are described that comprise one or more additional sex chromosomes such as 48,XXXY, 48,XXYY and 49,XXXXY. These rare conditions are often associated with increased risk for congenital malformations, additional medical problems, and a more complex psychological phenotype. Since 1963, apart from two infants, only four adult patients with a XXXYY pentasomy have been published as case report. The present paper critically reviews the existing literature and provides detailed assessments of a 25-year-old male with intellectual disability and autism. For the first time, this very rare pentasomy is now recorded using all information about developmental history as well as findings from genetic, somatic, endocrinological and neuropsychological examination. It is concluded that children born with abnormalities of the external genitalia should always be evaluated for genetic abnormalities in order to avoid unwanted delay of appropriately designed multidisciplinary medical and psychological treatment.

Noninvasive prenatal screening for fetal sex chromosome aneuploidies

INTRODUCTION

Sex chromosome aneuploidies (SCAs) are among the most common chromosome abnormalities observed in humans. Manifestations include low fertility, infertility, delayed language development, and dysfunction in motor development. Noninvasive prenatal screening (NIPS) based on cell-free fetal DNA from the peripheral blood of pregnant women is increasingly used for the screening of fetal chromosome abnormalities, including screening for fetal gender and fetal sex chromosome aneuploidy. A systematic review of the literature about NIPS for SCAs is needed.

AREAS COVERED

This review evaluated a vast array of published studies focusing on the clinical significance, detection methods, performance of NIPS for SCAs, and the management of positive SCA results following screening with the aim of facilitating a comprehensive and systematic understanding of NIPS for SCAs.

EXPERT COMMENTARY

Looking forward, NIPS is expected to become the primary screening test for common aneuploidies as well as other chromosome abnormalities, including some micro-deletions and micro-duplications, with the potential to transition from a screening test to a prenatal diagnosis method. Ultimately, the goal is to provide a safe and accurate method for increasing early diagnosis to improve long-term outcomes for the SCA patients and families by well- informed health care providers.