Evidence-based recommendations for delivering the diagnosis of X & Y chromosome multisomies in children, adolescents, and young adults: an integrative review

BACKGROUND

The diagnosis of supernumerary X & Y chromosome variations has increased following the implementation of genetic testing in pediatric practice. Empirical evidence suggests that the delivery of the diagnosis has a lasting impact on how affected individuals and their parents perceive and adapt to the diagnosis. The purpose of this review is to synthesize the literature to obtain useful recommendations for delivering a pediatric diagnosis of a sex chromosome multisomy (SCM) based upon a growing body of quantitative and qualitative literature on patient experiences.

METHODS

We conducted an integrative literature review using PubMed, Web of Science and CINAHL employing keywords "genetic diagnosis delivery," "genetic diagnosis disclosure," "sex chromosome aneuploidy," "Klinefelter syndrome" or ""47, XXY," "Jacob syndrome" or "47, XYY," "Trisomy X," "Triple X" or "47, XXX," and "48 XXYY from January 1, 2000, to October 31, 2023.

RESULTS

Literature supports that patients and parents value the provision of up-to-date information and connection with supportive resources. Discussion of next steps of care, including relevant referrals, prevents perceptions of provider abandonment and commitment to ongoing support. Proactively addressing special concerns such as disclosing the diagnosis to their child, family, and community is also beneficial. Tables are provided for useful information resources, medical specialties that may be required to support patients, and common misconceptions that interfere with accurate information about the diagnosis.

CONCLUSION

Patient experiences suggest there should be heightened attention to diagnosis delivery, in reference to the broader ethical and social impacts of a SCM diagnosis. We present recommendations for optimal disclosure of a SCM diagnosis in early and late childhood, adolescence, and young adulthood.

Clinical evaluation of noninvasive prenatal testing for sex chromosome aneuploidies in 9,176 Korean pregnant women: a single-center retrospective study

BACKGROUND

To evaluate the clinical significance of noninvasive prenatal testing (NIPT) for detecting fetal sex chromosome aneuploidies (SCAs) in Korean pregnant women.

METHODS

We retrospectively analyzed NIPT data from 9,176 women with singleton pregnancies referred to the CHA Biotech genome diagnostics center. Cell-free fetal DNA (cffDNA) was extracted from maternal peripheral blood, and high-throughput massively parallel sequencing was conducted. Subsequently, the positive NIPT results for SCA were validated via karyotype and chromosomal microarray analyses.

RESULTS

Overall, 46 cases were SCA positive after NIPT, including 20, 12, 8, and 6 for Turner, triple X, Klinefelter, and Jacob syndromes, respectively. Among 37 women with invasive prenatal diagnosis, 19 had true positive NIPT results. The overall positive predictive value (PPV) of NIPT for detecting SCAs was 51.35%. The PPV was 18.75% for Turner, 88.89% for triple X, 71.43% for Klinefelter, and 60.00% for Jacob's syndromes. NIPT accuracy for detecting sex chromosome trisomies was higher than that for sex chromosome monosomy (P = 0.002). No significant correlation was observed between fetal SCA incidence and maternal age (P = 0.914), except for the borderline significance of Jacob's syndrome (P = 0.048). No significant differences were observed when comparing NIPT and karyotyping validation for fetal SCA according to pregnancy characteristics.

CONCLUSION

Our data suggest that NIPT can reliably screen for SCAs, and it performed better in predicting sex chromosome trisomies compared with monosomy X. No correlation was observed between maternal age and fetal SCA incidence, and no association was observed between different pregnancy characteristics. The accuracy of these findings requires improvements; however, our study provides an important reference for clinical genetic counseling and further management. Larger scale studies, considering confounding factors, are required for accurate evaluation.

Information needs and health status in adolescents and young adults with differences of sex development or sex chromosome aneuploidies

INTRODUCTION

When and how to provide condition-related information to adolescents and young adults (AYAs) with differences of sex development or sex chromosome aneuploidies (DSDs or SCAs) is largely based on anecdotal experience and lacks informed guidance. For AYAs with a DSD or SCA, having accurate information is critical for attaining optimal adjustment and well-being, participating in decision making related to treatment options, and transitioning successfully to adult health care, yet prior studies have focused exclusively on parental perspectives and not on the views of adolescents themselves.

OBJECTIVE

The objective of this study was to describe unmet information needs in AYAs with a DSD or SCA and examine associations with perceived global health.

METHODS

Participants were recruited from specialty clinics at Children's Hospital of Philadelphia (n = 20) and Children's Hospital Colorado (n = 60). AYAs ages 12-21 years with a DSD or SCA and a parent completed a survey assessing perceived information needs across 20 topics, importance of those topics, and global health using the PROMIS Pediatric Global Health questionnaire (PGH-7).

RESULTS

AYAs had diagnoses of Klinefelter syndrome (41%), Turner syndrome (25%), and DSD (26%) and were 16.7 years (SD = 2.56) and 44% female. Parent participants were primarily mothers (81%). AYAs perceived that 48.09% of their information needs were unmet (SD = 25.18, range: 0-100). Parents perceived that 55.31% of AYAs' information needs were unmet (SD = 27.46 range: 5-100). AYAs and parents across conditions reported unmet needs related to information about transition to adult health care, financial support for medical care, and how the condition might affect the AYA's health in the future. While AYA-reported PGH-7 scores were not associated with percentage of AYA unmet information needs, parent-reported PGH-7 scores were (r = -.46, p < .001), such that lower parent-reported global health was associated with higher percentage of AYA unmet information needs.

DISCUSSION/CONCLUSION

On average, parents and AYAs perceived that half of AYAs' information needs were unmet, and a higher percentage of AYA unmet information needs was associated with lower perceived global health. The frequency of unmet needs in this sample of AYAs reflects an opportunity for improvement in clinical care. Future research is needed to understand how education to children and AYAs unfolds as they mature and to develop strategies to address the information needs of AYAs with a DSD or SCA, promote well-being, and facilitate AYA engagement in their own health care.

Performance of prenatal cfDNA screening for sex chromosomes

PURPOSE

To assess the performance of cell-free DNA (cfDNA) screening to detect sex chromosome aneuploidies (SCA) in an unselected obstetrical population with genetic confirmation.

METHODS

This was a planned secondary analysis of the multicenter, prospective SMART study. Patients receiving cfDNA results for autosomal aneuploidies and who had confirmatory genetic results for the relevant sex chromosomal aneuploidies were included. Screening performance for SCAs, including monosomy X (MX) and the sex chromosome trisomies (SCTs; 47,XXX; 47,XXY; 47,XYY) was determined. Fetal sex concordance between cfDNA and genetic screening was also evaluated in euploid pregnancies.

RESULTS

17,538 cases met inclusion criteria. Performance of cfDNA for MX, SCTs and fetal sex was determined in 17,297, 10,333 and 14,486 pregnancies, respectively. Sensitivity, specificity, and PPV of cfDNA were 83.3%, 99.9%, and 22.7% for MX, and 70.4%, 99.9%, and 82.6% for the combined SCTs. The accuracy of fetal sex prediction by cfDNA was 100%.

CONCLUSION

Screening performance of cfDNA for SCAs is comparable to that reported in other studies. The PPV for the SCTs was similar to the autosomal trisomies, while the PPV for MX was substantially lower. No discordance in fetal sex was observed between cfDNA and postnatal genetic screening in euploid pregnancies. These data will assist interpretation and counseling for cfDNA results for sex chromosomes.

X chromosome dosage and the genetic impact across human tissues

BACKGROUND

Sex chromosome aneuploidies (SCAs) give rise to a broad range of phenotypic traits and diseases. Previous studies based on peripheral blood samples have suggested the presence of ripple effects, caused by altered X chromosome number, affecting the methylome and transcriptome. Whether these alterations can be connected to disease-specific tissues, and thereby having clinical implication for the phenotype, remains to be elucidated.

METHODS

We performed a comprehensive analysis of X chromosome number on the transcriptome and methylome in blood, fat, and muscle tissue from individuals with 45,X, 46,XX, 46,XY, and 47,XXY.

RESULTS

X chromosome number affected the transcriptome and methylome globally across all chromosomes in a tissue-specific manner. Furthermore, 45,X and 47,XXY demonstrated a divergent pattern of gene expression and methylation, with overall gene downregulation and hypomethylation in 45,X and gene upregulation and hypermethylation in 47,XXY. In fat and muscle, a pronounced effect of sex was observed. We identified X chromosomal genes with an expression pattern different from what would be expected based on the number of X and Y chromosomes. Our data also indicate a regulatory function of Y chromosomal genes on X chromosomal genes. Fourteen X chromosomal genes were downregulated in 45,X and upregulated in 47,XXY, respectively, in all three tissues (AKAP17A, CD99, DHRSX, EIF2S3, GTPBP6, JPX, KDM6A, PP2R3B, PUDP, SLC25A6, TSIX, XIST, ZBED1, ZFX). These genes may be central in the epigenetic and genomic regulation of sex chromosome aneuploidies.

CONCLUSION

We highlight a tissue-specific and complex effect of X chromosome number on the transcriptome and methylome, elucidating both shared and non-shared gene-regulatory mechanism between SCAs.

The association between a carrier state of FMR1 premutation and numeric sex chromosome variations

PURPOSE

Women carriers of FMR1 premutation are at increased risk of early ovarian dysfunction and even premature ovarian insufficiency. The aim of this study was to examine a possible association between FMR1 permutation and numeric sex chromosome variations.

METHODS

A retrospective case-control study conducted in the reproductive center of a university-affiliated medical center. The primary outcome measure was the rate of sex chromosomal numerical aberrations, as demonstrated by haplotype analyses, in FMR1 premutation carriers compared to X-linked preimplantation genetic testing for monogenic/single gene defect (PGT-M) cycles for other indications that do not affect the ovarian follicles and oocytes.

RESULTS

A total of 2790 embryos with a final genetic analysis from 577 IVF PGT-M cycles were included in the final analysis. Mean age was similar between the groups, however, FMR1 carriers required more gonadotropins, and more women were poor responders with three or less oocytes collected. The ratio of embryos carrying a numeric sex chromosome variation was similar: 8.3% (138/1668) of embryos in the FMR1 group compared to 7.1% (80/1122) in the controls. A subgroup analysis based on age and response to stimulation has not demonstrated a significant difference either.

CONCLUSIONS

Although carriers of FMR1 premutation exhibit signs of reduced ovarian response, it does not seem to affect the rate of numeric sex chromosomal variation compared to women undergoing PGT-M for other indications. This suggests that the mechanism for chromosomal number aberrations in women at advanced maternal age are different to those FMR1 premutation carriers with poor ovarian reserve.

DNA methylation and behavioral dysfunction in males with 47,XXY and 49,XXXXY: a pilot study

Background

Equal dosage of X-linked genes between males and females is maintained by the X-inactivation of the second X chromosome in females through epigenetic mechanisms. Boys with aneuploidy of the X chromosome exhibit a host of symptoms such as low fertility, musculoskeletal anomalies, and cognitive and behavioral deficits that are presumed to be caused by the abnormal dosage of these genes. The objective of this pilot study is to assess the relationship between CpG methylation, an epigenetic modification, at several genes on the X chromosome and behavioral dysfunction in boys with supernumerary X chromosomes.

Results

Two parental questionnaires, the Behavior Rating Inventory of Executive Function (BRIEF) and Child Behavior Checklist (CBCL), were analyzed, and they showed expected differences in both internal and external behaviors between neurotypical (46,XY) boys and boys with 49,XXXXY. There were several CpGs in AR and MAOA of boys with 49,XXXXY whose methylation levels were skewed from levels predicted from having one active (Xa) and three inactive (Xi) X chromosomes. Further, methylation levels of multiple CpGs in MAOA showed nominally significant association with externalizing behavior on the CBCL, and the methylation level of one CpG in AR showed nominally significant association with the BRIEF Regulation Index.

Conclusions

Boys with 49,XXXXY displayed higher levels of CpG methylation at regulatory intronic regions in X-linked genes encoding the androgen receptor (AR) and monoamine oxidase A (MAOA), compared to that in boys with 47,XXY and neurotypical boys. Our pilot study results suggest a link between CpG methylation levels and behavior in boys with 49,XXXXY.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-021-01123-4.

Modeling familial predictors of proband outcomes in neurogenetic disorders: initial application in XYY syndrome

BACKGROUND

Disorders of gene dosage can significantly increase risk for psychopathology, but outcomes vary greatly amongst carriers of any given chromosomal aneuploidy or sub-chromosomal copy number variation (CNV). One potential path to advance precision medicine for neurogenetic disorders is modeling penetrance in probands relative to observed phenotypes in their non-carrier relatives. Here, we seek to advance this general analytic framework by developing new methods in application to XYY syndrome-a sex chromosome aneuploidy that is known to increase risk for psychopathology.

METHODS

We analyzed a range of cognitive and behavioral domains in XYY probands and their non-carrier family members (n = 58 families), including general cognitive ability (FSIQ), as well as continuous measures of traits related to autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD). Proband and relative scores were compared using covariance, regression and cluster analysis. Comparisons were made both within and across traits.

RESULTS

Proband scores were shifted away from family scores with effect sizes varying between 0.9 and 2.4 across traits. Only FSIQ and vocabulary scores showed a significant positive correlation between probands and their non-carrier relatives across families (R² ~ 0.4). Variability in family FSIQ also cross-predicted variability in proband ASD trait severity. Cluster analysis across all trait-relative pairings revealed that variability in parental psychopathology was more weakly coupled to their XYY versus their euploid offspring.

CONCLUSIONS

We present a suite of generalizable methods for modeling variable penetrance in aneuploidy and CNV carriers using family data. These methods update estimates of phenotypic penetrance for XYY and suggest that the predictive utility of family data is likely to vary for different traits and different gene dosage disorders.

TRIAL REGISTRATIONS

ClinicalTrials.gov NCT00001246 , "89-M-0006: Brain Imaging of Childhood Onset Psychiatric Disorders, Endocrine Disorders and Healthy Controls." Date of registry: 01 October 1989.

Characterization of autism spectrum disorder and neurodevelopmental profiles in youth with XYY syndrome

BACKGROUND

XYY syndrome is a sex chromosome aneuploidy that occurs in ~ 1/850 male births and is associated with increased risk for neurodevelopmental difficulties. However, the profile of neurodevelopmental impairments, including symptoms of autism spectrum disorder (ASD) in XYY remains poorly understood. This gap in knowledge has persisted in part due to lack of access to patient cohorts with dense and homogeneous phenotypic data.

METHODS

We evaluated a single-center cohort of 64 individuals with XYY aged 5-25 years, using a standardized battery of cognitive and behavioral assessments spanning developmental milestones, IQ, adaptive behavior, academic achievement, behavioral problems, and gold-standard diagnostic instruments for ASD. Our goals were to (i) detail the neurodevelopmental profile of XYY with a focus on ASD diagnostic rates and symptom profiles, (ii) screen phenotypes for potential ascertainment bias effects by contrasting pre- vs. postnatally diagnosed XYY subgroups, and (iii) define major modules of phenotypic variation using graph-theoretical analysis.

RESULTS

Although there was marked inter-individual variability, the average profile was characterized by some degree of developmental delay, and decreased IQ and adaptive behavior. Impairments were most pronounced for language and socio-communicative functioning. The rate of ASD was 14%, and these individuals exhibited autism symptom profiles resembling those observed in ASD without XYY. Most neurodevelopmental dimensions showed milder impairment among pre- vs. postnatally diagnosed individuals, with clinically meaningful differences in verbal IQ. Feature network analysis revealed three reliably separable modules comprising (i) cognition and academic achievement, (ii) broad domain psychopathology and adaptive behavior, and (iii) ASD-related features.

CONCLUSIONS

By adding granularity to our understanding of neurodevelopmental difficulties in XYY, these findings assist targeted clinical assessment of newly identified cases, motivate greater provision of specialized multidisciplinary support, and inform future efforts to integrate behavioral phenotypes in XYY with neurobiology.

TRIAL REGISTRATIONS

ClinicalTrials.gov NCT00001246 , "89-M-0006: Brain Imaging of Childhood Onset Psychiatric Disorders, Endocrine Disorders and Healthy Controls."

Screening for Sex Chromosome Aneuploidy by Cell-Free DNA Testing: Patient Choice and Performance

OBJECTIVE

To study patient choice regarding testing for sex chromosome aneuploidy (SCA) and the performance of cell-free DNA (cfDNA) screening for SCA.

METHODS

Patient choice regarding screening for SCA and factors influencing this choice were evaluated in a single center. In a subsequent two-center study, cases that screened positive for SCA were analyzed to determine the positive predictive value (PPV) for each SCA.

RESULTS

In all, 1,957 (61.9%) of the 3,162 patients undergoing cfDNA testing opted for SCA screening. Regression analysis demonstrated that independent predictors of a patient's decision for SCA were earlier gestational age, spontaneous conception, and cfDNA chosen as a primary method of screening. A total of 161 cases screened positive for SCA and follow-up data were available for 118 (73.3%). Forty-six of the 61 cases of 45,X were false-positive results and 15 were concordant with the fetal karyotype (PPV = 24.6%). Seventeen of the 22 cases of 47,XXX were false positive and 5 concordant (PPV = 22.7%). Eleven of the 30 cases of 47,XXY were false positive and 19 concordant (PPV = 63.3%). All 5 cases of 47,XYY were correctly identified, thus yielding a PPV of 100%.

CONCLUSION

More than half of the patients undergoing cfDNA aneuploidy screening also opted for SCA testing, but they were less likely to do so in the presence of an increased risk of trisomy. SCAs involving the X chromosome had a lower PPV than those involving the Y chromosome.

Partnering with parents to disclose Klinefelter syndrome to their child

In paediatrics, a diagnosis of Klinefelter syndrome can occur after prenatal testing or because of symptoms such as learning difficulties or incomplete puberty. After the diagnosis, parents have to decide when and how to speak about this condition to their child. Parents and healthcare professionals (HCPs) may have different perceptions related to disclosure of this diagnosis. Due to the absence of clear guidelines, parents and HCPs may feel uncomfortable discussing the condition and may hide the truth in a prolonged fashion.

CONCLUSION

For patients with a prenatal diagnosis, we recommend a gradual and personalised disclosure process starting between the ages of 5 and 13 years. For older patients, a personalised approach should also be the goal. Various communication strategies and recommendations regarding disclosure of Klinefelter syndrome are proposed.

Non-invasive Prenatal Testing: Technologies, Clinical Assays and Implementation Strategies for Women's Healthcare Practitioners

The field of prenatal genetic testing has exploded with new non-invasive technologies and test options in the past several years. It is challenging for women's healthcare providers to keep up with the multitude of publications and provide patients with the most accurate and up-to-date information possible regarding prenatal testing. In this article, we examine the sequencing technologies that provide the framework for non-invasive prenatal testing (NIPT) and review the major North American NIPT clinical validation studies published in 2011 and 2012. This paper also compares and contrasts the commercially available non-invasive prenatal tests in the United States, discusses clinical implementation recommendations from professional societies and highlights considerations for genetic counseling.