Cognitive and motor development during childhood in boys with Klinefelter syndrome

Hormone Therapy During Infancy or Early Childhood for Patients with Hypogonadotropic Hypogonadism, Klinefelter or Turner Syndrome: Has the Time Come?

Managing patients unable to produce sex steroids using gonadotropins to mimic minipuberty in hypogonadotropic hypogonadism, or sex steroids in patients with Klinefelter or Turner syndrome, is promising. There is a need to pursue research in this area, with large prospective cohorts and long-term data before these treatments can be routinely considered.

Understanding the Neuropsychological Implications of Klinefelter Syndrome in Pediatric Populations: Current Perspectives

Klinefelter syndrome (KS), also known as 47,XXY, is a genetic disorder characterized by the presence of an extra X chromosome. Despite the prevalence of verbal learning disabilities, memory impairments, and executive function deficits in individuals with KS, comprehensive research on the neuropsychological profiles of affected children and adolescents remains limited. Additionally, KS has been associated with comorbid conditions such as depression, anxiety, schizophrenia, attention-deficit hyperactivity disorder (ADHD), and autism spectrum disorders (ASDs). However, systematic investigations into the neuropsychological manifestations of KS in pediatric populations are scarce. Therefore, the primary objectives of this review are to provide an overview of key studies examining the neuropsychological profiles of children and adolescents with KS and to delineate the limitations and implications of existing research findings. By synthesizing available literature, this review aims to bridge the gap in understanding the cognitive and behavioral characteristics of children and adolescents with KS, shedding light on potential avenues for future research and clinical interventions. Ultimately, this review serves as a valuable resource for clinicians, researchers, policymakers, parents, and educators involved in the assessment and management of the neuropsychological aspects of Klinefelter syndrome in pediatric populations.

Social Communication in Young Children With Sex Chromosome Trisomy (XXY, XXX, XYY): A Study With Eye Tracking and Heart Rate Measures

OBJECTIVE

Children with sex chromosome trisomy (SCT) have an increased risk for suboptimal development. Difficulties with language are frequently reported, start from a very young age, and encompass various domains. This cross-sectional study examined social orientation with eye tracking and physiological arousal responses to gain more knowledge on how children perceive and respond to communicative bids and evaluated the associations between social orientation and language outcomes, concurrently and 1 year later.

METHOD

In total, 107 children with SCT (33 XXX, 50 XXY, and 24 XYY) and 102 controls (58 girls and 44 boys) aged between 1 and 7 years were included. Assessments took place in the USA and Western Europe. A communicative bids eye tracking paradigm, physiological arousal measures, and receptive and expressive language outcomes were used.

RESULTS

Compared to controls, children with SCT showed reduced attention to the face and eyes of the on-screen interaction partner and reduced physiological arousal sensitivity in response to direct versus averted gaze. In addition, social orientation to the mouth was related to concurrent receptive and expressive language abilities in 1-year-old children with SCT.

CONCLUSIONS

Children with SCT may experience difficulties with social communication that extend past the well-recognized risk for early language delays. These difficulties may underlie social-behavioral problems that have been described in the SCT population and are an important target for early monitoring and support.

Genetic outcomes in children with developmental language disorder: a systematic review

Introduction

Developmental language disorder (DLD) is a common childhood condition negatively influencing communication and psychosocial development. An increasing number of pathogenic variants or chromosomal anomalies possibly related to DLD have been identified. To provide a base for accurate clinical genetic diagnostic work-up for DLD patients, understanding the specific genetic background is crucial. This study aims to give a systematic literature overview of pathogenic variants or chromosomal anomalies causative for DLD in children.

Methods

We conducted a systematic search in PubMed and Embase on available literature related to the genetic background of diagnosed DLD in children. Included papers were critically appraised before data extraction. An additional search in OMIM was performed to see if the described DLD genes are associated with a broader clinical spectrum.

Results

The search resulted in 15,842 papers. After assessing eligibility, 47 studies remained, of which 25 studies related to sex chromosome aneuploidies and 15 papers concerned other chromosomal anomalies (SCAs) and/or Copy Number Variants (CNVs), including del15q13.1-13.3 and del16p11.2. The remaining 7 studies displayed a variety of gene variants. 45 (candidate) genes related to language development, including FOXP2, GRIN2A, ERC1, and ATP2C2. After an additional search in the OMIM database, 22 of these genes were associated with a genetic disorder with a broader clinical spectrum, including intellectual disability, epilepsy, and/or autism.

Conclusion

Our study illustrates that DLD can be related to SCAs and specific CNV's. The reported (candidate) genes (n = 45) in the latter category reflect the genetic heterogeneity and support DLD without any comorbidities and syndromic language disorder have an overlapping genetic etiology.

Executive Dysfunction in Klinefelter Syndrome: Associations With Brain Activation and Testicular Failure

CONTEXT

Executive dysfunction is a well-recognized component of the cognitive phenotype of Klinefelter syndrome (KS), yet the neural basis of KS-associated cognitive weaknesses, and their association with testicular failure is unknown.

OBJECTIVE

We investigated executive function, brain activation, and pubertal development in adolescents with and without KS.

METHODS

Forty-three adolescents with KS (mean age 12.3 ± 2.3 years) and 41 typically developing boys (mean age 11.9 ± 1.8 years) underwent pubertal evaluation, behavioral assessment, and completed functional magnetic resonance imaging (fMRI) as they performed an executive function task, the go/no-go task. Group differences in activation were examined. Associations among activation, executive function, and pubertal development measures were tested in secondary analyses.

RESULTS

Boys with KS exhibited reduced executive function, as well as lower activation in brain regions subserving executive function, including the inferior frontal gyrus, anterior insula, dorsal anterior cingulate cortex, and caudate nucleus. Secondary analyses indicated that the magnitude of activation differences in boys with KS was associated with severity of pubertal developmental delay, as indexed by lower testosterone (t(36) = 2.285; P = .028) and lower testes volume (t(36) = 2.238; P = .031). Greater parent-reported attention difficulties were additionally associated with lower testicular volume (t(36) = -2.028; P = .050).

CONCLUSION

These findings indicate a neural basis for executive dysfunction in KS and suggest alterations in pubertal development may contribute to increased severity of this cognitive weakness. Future studies that examine whether these patterns change with testosterone replacement therapy are warranted.

Cognition, Academic Achievement, Adaptive Behavior, and Quality of Life in Child and Adolescent Boys with Klinefelter Syndrome

OBJECTIVE

Klinefelter syndrome (KS; 47, XXY), the most common sex chromosome aneuploidy in males, is characterized by testicular failure and testosterone deficiency as well as a variety of cognitive, social, and emotional challenges. In the current study, we aimed to clarify the cognitive-behavioral profile of peripubertal boys with KS using measures of cognition, academic achievement, adaptive behavior, and quality of life.

METHOD

We compared 47 boys with KS (7-16 years of age) with 55 performance IQ-matched boys without KS on measures of cognition (WISC-V), executive function (BRIEF-2), academic achievement (KTEA-3), adaptive behavior (Vineland-3), and quality of life (PROMIS). In exploratory analyses, we examined associations among these measures and potential associations with pubertal metrics.

RESULTS

Boys with KS demonstrated a significantly different profile of cognition, behavioral ratings of executive function, academic achievement, adaptive behavior, and quality of life compared with their typically developing peers, with, on average, lower functioning. The groups showed significantly different correlations between cognition and aspects of quality of life. No associations were observed between behavior and pubertal development.

CONCLUSION

Taken together, these findings indicated that boys with KS are at increased risk for cognitive difficulties, which may affect academic achievement, adaptive behavior, and quality of life. Although initial exploratory analyses indicated that the magnitude of these alterations was not correlated with severity of testicular failure, longitudinal analyses currently being conducted by our group may help clarify the trajectory of these difficulties through the pubertal transition and testosterone replacement.

Advances in Genetics and Epigenetics of Developmental Coordination Disorder in Children

Developmental coordination disorder (DCD) is a developmental disorder characterized by impaired motor coordination, often co-occurring with attention deficit disorder, autism spectrum disorders, and other psychological and behavioural conditions. The aetiology of DCD is believed to involve brain changes and environmental factors, with genetics also playing a role in its pathogenesis. Recent research has identified several candidate genes and genetic factors associated with motor impairment, including deletions, copy number variations, single nucleotide polymorphisms, and epigenetic modifications. This review provides an overview of the current knowledge in genetic research on DCD, highlighting the importance of continued research into the underlying genetic mechanisms. While evidence suggests a genetic contribution to DCD, the evidence is still in its early stages, and much of the current evidence is based on studies of co-occurring conditions. Further research to better understand the genetic basis of DCD could have important implications for diagnosis, treatment, and our understanding of the condition's aetiology.

Structural and pragmatic language in young children with sex chromosome trisomy (XXX, XXY, XYY): Predictive value for neurobehavioral problems one year later

Objective: To investigate pragmatic language abilities in young children with an increased risk for adverse neurobehavioral and neurocognitive outcomes due to an extra X or Y chromosome (sex chromosome trisomy; SCT) and to investigate to what degree early structural and pragmatic language abilities are predictive of neurobehavioral problems one year later. Method: In total, 72 children with SCT and 71 controls aged 3-7 years were included. Language assessments included parent-reported pragmatic language skills and direct assessment of structural language abilities. Parent-reported behavioral outcomes were measured one year after the initial language assessment. Results: Children with SCT demonstrated weaker pragmatic language skills compared to controls. These differences were not driven by karyotype, time of diagnosis, or ascertainment bias and irrespective of the presence of structural language impairment. Odds of having pragmatic difficulties was 23 times higher in the SCT group, with 25% of the children not meeting age-expectations. In addition, language, in particular pragmatic language, was an important predictor for later affective, oppositional defiant, pervasive developmental, attention deficit, and social-emotional problems in young children with SCT. Conclusions: This study is one of the first studies that directly illustrates the relationship between language and behavioral outcomes in children with SCT. Our results stress the importance to closely monitor pragmatic language in addition to structural language in clinical care of children with SCT, as pragmatic language abilities could serve as an early marker for children at risk for developing behavioral problems.

Speech Sound Development in 18-Month-Old Children With Sex Chromosome Trisomies

PURPOSE

This study aimed to describe speech sound development in a group of 18-month-old children with sex chromosome trisomies (SCTs), compared with a group of typically developing (TD) peers. Concurrent and longitudinal relationships between speech sound abilities and lexical development were examined.

METHOD

A group of 76 children aged 18 months, 38 children prenatally diagnosed with SCTs (12 with XXY, 12 with XYY, and 14 with XXX) and 38 TD children, participated in the study. From video recordings of semistructured naturalistic parent-child play sessions, quantitative and qualitative measures of speech sound development were collected (e.g., the number of consonants, type and place of articulation, and syllable structures used), and group differences were observed. The relationships between the number of consonants produced and vocabulary size at 18 and 24 months were assessed.

RESULTS

At 18 months, children with SCTs used a significantly lower number of consonants than TD children. Qualitatively, children with SCTs used significantly fewer articulatory complex consonants (fricative/affricates) and a more restricted inventory of syllable structures. The number of consonants used was significantly correlated with lexical development at 18 months. Moreover, in the SCTs group (but not in the TD group), the children with lower speech sound development at 18 months showed a significantly smaller vocabulary growth between 18 and 24 months than those with higher speech-sound development.

CONCLUSIONS

Toddlers with SCTs showed a significantly delayed speech sound development pattern rather than an atypical one. Children with SCTs with low speech sound development also showed lower vocabulary growth between 18 and 24 months of age. These results can be clinically relevant for follow-up and treatment planning for children with SCTs.

Novel Neurocognitive Profile in a Minority of Boys with 47,XXY (Klinefelter Syndrome)

INTRODUCTION

47,XXY, also known as Klinefelter syndrome, is the most commonly occurring sex chromosomal variation (1:660). The neurocognitive profile of boys with 47,XXY, in addition to verbal abilities, language skills, and general intelligence, has been explored in this study.

METHODS

Fifty-five participants with 47,XXY were segregated into groups according to their performance on the Wechsler Intelligence Scale for Children (WISC): (1) those with a higher performance intelligence quotient (PIQ) in comparison with their verbal IQ (VIQ) and (2) those with a higher VIQ compared with their PIQ. Two-tailed independent t tests were completed to analyze group differences.

RESULTS

Our study results demonstrate novel findings that one-third of subjects have higher verbal capabilities than perceptual skills. Those participants who showed the typical presentation of 47,XXY with increased PIQ in comparison with their VIQ excelled on perceptual and visual spatial subtests on the WISC and on nonverbal IQ on the Leiter International Performance Scale-III. In addition, it was found that expressive and receptive vocabulary skills were commensurate in both groups, which has not been reported previously.

DISCUSSION

To the best of our knowledge, this is the first study to identify an alternative profile of 47,XXY with increased verbal capabilities in comparison with perceptual skills. In addition, previous research has found that boys with 47,XXY often show increased receptive vocabulary skills in comparison with their expressive vocabulary skills early in life. Therefore, our findings of commensurate expressive and receptive vocabulary skills suggest that age may be an impactful factor in vocabulary development. Further research is necessary to determine individualized treatment options for these patients, focusing on the specific cognitive profile they present.

Language Development in Sex Chromosome Trisomies: Developmental Profiles at 2 and 4 Years of Age, and Predictive Measures

PURPOSE

Describing language development in children with sex chromosome trisomies (SCT) and testing the predictive value of early language measures on later outcomes.

METHOD

Thirteen children with SCT were followed longitudinally. Their developmental profile was assessed, with particular attention to language, at 2 and 4 years. The predictive value of direct (spontaneous speech analysis) and indirect (communicative development inventory) language measures at 2 on performances at 4 was tested.

RESULTS

Language performances at both ages were lower than non-verbal development. At 2, more than 50% of the group produced less than 50 words. At 4, impaired performances were observed in speech sound development and expressive morpho-syntax. Direct measures of Pre-syntactic development predicted later global language outcomes and Sentence Repetition. The number of consonants used at 2 was significantly related to Nonword Repetition at 4.

CONCLUSIONS

The study highlights the importance of early detection and careful follow-up for children with SCT.

The developmental impact of sex chromosome trisomies on emerging executive functions in young children: Evidence from neurocognitive tests and daily life skills

Sex chromosomal trisomies (SCT) are associated with impairments in executive functions in school-aged children, adolescents, and adults. However, knowledge on preschool development of executive functions is limited but greatly needed to guide early intervention. The current study examined emerging executive functions in young children with SCT. Participants were 72 SCT children and 70 population-based controls, aged 3-7 years, who completed a neurocognitive assessment of both global executive function (MEFS) and verbal executive function skills (NEPSY Word Generation). Caregivers completed the Behavior Rating Inventory of Executive Function (BRIEF) questionnaire to capture real-world behavioral manifestations of impairments in executive functions. Results showed that impairments were significantly more prevalent in SCT than in controls and already present from 3 years, specifically verbal executive functions and working memory. Broader more pronounced impairments were found in older children with SCT. Age was significantly related to executive functions, but specific domains showed different relations with age. For example, deficits in planning and organizing remained evident with older age in SCT whereas it declined with age in controls. Impairments in executive functions were present across different levels of intelligence. Already at an early age, impairments across executive functions should be considered part of the neurodevelopmental profile of SCT, which appear more prominent at later age. Future studies should investigate developmental pathways of executive functions in SCT, given its relevance in cognitive, social, and emotional development. Executive functions should be screened and monitored in children with SCT and could be an important target of preventive intervention.

The impact of Klinefelter syndrome on socioeconomic status: a multicenter study

Klinefelter syndrome (KS) is associated with an increased risk of neuropsychological morbidity, such as learning disabilities, which may have a significant impact on socioeconomic status (SES). The objective of this study was to investigate the SES in men with KS and to associate this outcome with social participation, age at diagnosis, testosterone therapy and physical and mental health status. Men with KS were recruited in 14 clinical study centers in six European countries which participated in the European dsd-LIFE study. Two hundred five men with KS were eligible for inclusion. Male normative data from the European Social Surveys (ESS) were used for comparison. Data related to education, occupation, satisfaction with income and householding were collected. Compared to the ESS reference population, fewer men with KS achieved a high level of education (13% vs 25%, P < 0.001). There was a significant difference in having a paid job (55% vs 66%, P < 0.001), and the percentage of absence by sickness or disability was higher among men with KS (10% vs 3%, P < 0.001). Furthermore, satisfaction with current household's income was lower (32% vs 42%, P < 0.01). Lower scores for subjective general health were associated with lower scores for these outcomes. Men with KS achieve on average lower levels of education, occupation and report less satisfaction with income compared to the ESS reference population. The presence of health problems and lower scores of subjective general health was related to lower levels of occupation and lower satisfaction with income in men with KS.

A juvenile locomotor program promotes vocal learning in zebra finches

The evolution and development of complex, learned motor skills are thought to be closely associated with other locomotor movement and cognitive functions. However, it remains largely unknown how different neuromuscular programs may interconnect during the protracted developmental process. Here we use a songbird to examine the behavioral and neural substrates between the development of locomotor movement and vocal-motor learning. Juvenile songbirds escalate their locomotor activity during the sensitive period for vocal learning, followed by a surge of vocal practice. Individual variability of locomotor production is positively correlated with precision of tutor imitation and duration of multi-syllable sequences. Manipulation of juvenile locomotion significantly impacts the precision of vocal imitation and neural plasticity. The locomotor program developed during the sensitive period of vocal learning may enrich the neural substrates that promote the subsequent development of vocal learning.

Increased movement is associated with improved vocal activity in young zebra finches, while reducing locomotion leads to poor vocal learning. These results suggest that exercise in juvenile birds may actually promote their ability to learn and produce songs.

KIF2C affects sperm cell differentiation in patients with Klinefelter syndrome, as revealed by RNA-Seq and scRNA-Seq data

Klinefelter syndrome (KS) is a leading contributor to male infertility and is characterised by complex and diverse clinical features; however, genetic changes in the KS transcriptome remain largely unknown. We therefore used transcriptomic and single‐cell RNA sequencing (scRNA‐seq) datasets from KS versus normal populations through the Gene Expression Omnibus (GEO) database to identify gene biomarkers associated with the occurrence of KS. We identified a total of 700 differentially expressed genes (DEGs) and completed Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), enrichment pathway analysis and protein‐protein interaction (PPI) network analysis. A total of four unreported KS‐related hub genes (KIF2C, MRPS2, RPS15 and TSFM) were identified. Validation of the single‐cell sequencing dataset showed that only KIF2C and RPS15 were expressed in spermatocytes and that they were differentially expressed in sperm cells. Further construction of the developmental trajectories of these two genes in sperm cells showed that the KIF2C gene showed an upward trend throughout the differentiation and development of sperm cells. In conclusion, we report here that KIF2C may be closely related to the differentiation and development of sperm cells in KS patients, which is important for revealing the molecular mechanism of KS and conducting further studies.

Effect of sex chromosome number variation on attention-deficit/hyperactivity disorder symptoms, executive function, and processing speed

AIM

To study sex differences in attention-deficit/hyperactivity disorder (ADHD) symptoms, we explored whether X chromosome absence or excess is independently associated with deficits in attention and hyperactivity, executive function, and processing speed.

METHOD

We assessed 116 children (ages 3y 10mo-11y 11mo, mean 8y 5mo, SD 1y 11mo) with a variable number of sex chromosomes: 36 females with Turner syndrome (45, X0), 20 males with Klinefelter syndrome (47, XXY), 37 typically developing females (XX), and 23 typically developing males (XY).

RESULTS

X chromosome absence was associated with increased attention problems, hyperactivity, and deficits in inhibitory control, compared with female children with XX (all p<0.003). Conversely, X chromosome excess was associated with weakness in working memory (p=0.018) and approached significance for attention problems (p=0.071) but not with hyperactivity, or weakness in inhibitory control relative to male children with XY. Using non-parametric effect size to quantify the clinical effect revealed that X chromosome absence affected attention, hyperactivity, executive function, and processing speed (all r>0.4), while X excess affected in-laboratory as well as parent-reported working memory (all r>0.4).

INTERPRETATION

Our observations provide compelling evidence that the absence or excess of an X chromosome distinctly affects cognition and behaviors associated with ADHD.

Pseudoautosomal Region 1 Overdosage Affects the Global Transcriptome in iPSCs From Patients With Klinefelter Syndrome and High-Grade X Chromosome Aneuploidies

Klinefelter syndrome (KS) is the most prevalent aneuploidy in males and is characterized by a 47,XXY karyotype. Less frequently, higher grade sex chromosome aneuploidies (HGAs) can also occur. Here, using a paradigmatic cohort of KS and HGA induced pluripotent stem cells (iPSCs) carrying 49,XXXXY, 48,XXXY, and 47,XXY karyotypes, we identified the genes within the pseudoautosomal region 1 (PAR1) as the most susceptible to dosage-dependent transcriptional dysregulation and therefore potentially responsible for the progressively worsening phenotype in higher grade X aneuploidies. By contrast, the biallelically expressed non-PAR escape genes displayed high interclonal and interpatient variability in iPSCs and differentiated derivatives, suggesting that these genes could be associated with variable KS traits. By interrogating KS and HGA iPSCs at the single-cell resolution we showed that PAR1 and non-PAR escape genes are not only resilient to the X-inactive specific transcript (XIST)-mediated inactivation but also that their transcriptional regulation is disjointed from the absolute XIST expression level. Finally, we explored the transcriptional effects of X chromosome overdosage on autosomes and identified the nuclear respiratory factor 1 (NRF1) as a key regulator of the zinc finger protein X-linked (ZFX). Our study provides the first evidence of an X-dosage-sensitive autosomal transcription factor regulating an X-linked gene in low- and high-grade X aneuploidies.

[Formula: see text]A cross-sectional study of early language abilities in children with sex chromosome trisomy (XXY, XXX, XYY) aged 1-6 years

Children with sex chromosome trisomy (SCT) are at increased risk for developing language difficulties. Earlier studies have reported that as many as 70-80% of individuals with SCT show some form of language difficulties. Language develops rapidly in the first years of life; knowledge about language development at an early age is needed. The present study aims to identify the language abilities of young children with SCT across multiple language domains and to identify the percentage of children that, according to clinical guidelines, have language difficulties. Children between the ages of 1-6-years (NSCT = 103, Ncontrols = 102) were included. Nonverbal communication, early vocabulary, semantic, syntax, and phonological skills were assessed. Language difficulties were already present in 1-year-old children with SCT and across the age range in various language domains. Clinical classification showed that, depending on the assessed domain, 14.8-50.0% of the children scored below the 16th percentile. There was no effect of time of diagnosis, ascertainment bias, research site, nor SCT specific karyotype (XXX, XXY, XYY) on language outcomes. Overall, language difficulties can already be present in very young children with SCT within various language domains. These findings appear to be robust within the SCT group. These results highlight the importance of monitoring both receptive and expressive language development already at the earliest stages of nonverbal communication. Finally, as early language skills are the building blocks for later social communication, literacy, and self-expression, studies that investigate the effect of early interventions on later language outcomes are warranted.

Quality of life in Klinefelter patients on testosterone replacement therapy compared to healthy controls: an observational study on the impact of psychological distress, personality traits, and coping strategies

PURPOSE

We aimed to verify if 1 year-testosterone-replacement therapy could produce a psychopathological recovery and a satisfactory quality of life in Klinefelter syndrome (KS) patients compared to matched healthy controls. Further, we analyzed personality traits and coping strategies, an issue not yet examined in androgen-treated KS patients. We also enquired whether any of the sociodemographic and psychological variables might predict a patient's general and sexual life satisfaction.

METHODS

The Quality of Life Enjoyment and Satisfaction Questionnaire and the Temperament and Character Inventory-Revised were administered to both 23 KS patients and matched healthy subjects. Psychopathology was investigated by the Symptom Checklist-90-Revised (SCL-90-R) and the Mini-mental State Examination. The COPE Inventory was used to identify cognitive and behavioral strategies to manage disease-related distress.

RESULTS

In testosterone-treated KS patients, when compared with controls, SCL-90-R subscales analysis evidenced high psychological distress, mainly presented as obsessive thoughts, hanger-hostility, phobias, and psychoticism. Self-directedness and self-transcendence, along with the prevalent use of emotion-focused coping strategies, outlined the personality of our KS patients. Depression and somatization proved to be predictors of general life dissatisfaction. Depression, anger-hostility, and paranoid ideation, instead, emerged as predictors of sexual life dissatisfaction.

CONCLUSION

Endocrinologists should cooperate with mental health providers to foster a better outcome of the disease in KS patients.

Klinefelter syndrome or testicular dysgenesis: Genetics, endocrinology, and neuropsychology

Klinefelter syndrome (47,XXY) is a frequent chromosomal disorder among males, often presenting with hypergonadotropic hypogonadism, small firm testicles, metabolic disorders, neurocognitive challenges, and increased height. Neurologic disorders such as epilepsy, seizures, and tremor as well as psychiatric disorders are also seen more frequently. The neurocognitive deficits seen are present in many areas of cognition, typically affecting general cognitive abilities, language, and executive functioning. Also, social dysfunction is frequent. Dyslexia is present in more than half of all males. Brain imaging studies generally show a typical pattern, with many nuclei and brain areas being smaller than among controls. However, it has not been possible to link the brain alterations found in imaging studies with the neurocognitive profile. The genetics underlying the phenotypic traits found among males with Klinefelter syndrome still remains to be elucidated; however, recent studies have described pervasive changes in the methylome and transcriptome and new and interesting candidate genes have been pinpointed, but their involvement in the phenotype of Klinefelter syndrome has not been proven.

[Klinefelter syndrome: literature review on using modern methods of assisted reproductive technologies]

The article reviews scientific papers devoted to the problem of reproductive health in men with Klinefelter syndrome (KS). Pathogenesis from a very early age (in utero), the possibility of ensuring biological paternity upon reaching sexual maturity and the risk of chromosomal abnormalities in offspring are discussed. Despite the fact that KS is one of the most common causes of male infertility associated with chromosomal abnormalities, due to the variability of clinical manifestations the proportion of patients identified before puberty did not exceed 10% before the widespread introduction of non-invasive prenatal testing. According to the research results presented in the article, the reproductive potential of males with KS is often already reduced in early childhood. These circumstances should be considered when choosing further patient management tactics.There are few reports on the onset of spontaneous pregnancy in the case of KS, so ensuring biological paternity in this group of patients is often possible only using surgical methods of sperm extraction and assisted reproductive technologies. This article discusses methods like testicular sperm extraction (TESE) and microdissection testicular sperm extraction (mTESE) in terms of their effectiveness and safety for the patient, and the factors influencing the outcome of the operation. The optimal period of these manipulations seems to be the patient's age from 18 to 30 years, although the feasibility of adolescent boys undergoing the aforementioned procedures is highly controversial.The research papers presented in the article suggest that the risk of transmitting chromosomal abnormalities to offspring is rather low, which does not exclude the need for medical and genetic counseling to explain all possible risks to the patient. Preimplantation or intrauterine diagnostics are also deemed necessary.

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.

Clinical manifestation, diagnosis, and treatment of Klinefelter syndrome

Klinefelter syndrome is the most common congenital chromosomal syndrome in men. Clinical manifestations of Klinefelter syndrome vary greatly depending on the level of expression of the added X chromosome, the sensitivity of the androgen receptor, and the testosterone level. On average, the likelihood of a lifetime diagnosis of Klinefelter syndrome patients is less than 40%, and more than 60% of patients are unaware of their condition. Klinefelter syndrome patients in infancy sometimes have speech impairment; however, there are more cases without symptoms. In the early stages of puberty, there are many normal puberty development cases, but after mid-puberty, secondary sexual characteristics stop progressing. In adulthood, it is often diagnosed as a non-obstructive azoospermia disease. After middle-age, an increase in various metabolic disorders due to testosterone reduction appears as the main symptom. Testosterone treatment can promote the development of secondary sexual characteristics from puberty. Diagnosing a patient with Klinefelter syndrome due to infertility in adulthood may cause a psychological shock; therefore, a psychotherapeutic approach is also essential. Klinefelter syndrome is a disease that requires lifelong management, and in most cases the quality of life of patients and their families can be improved with appropriate therapeutic intervention. Because there are many cases without symptoms, it is important to screen suspected patients through active chromosomal testing.

Executive function in XXY: Comparison of performance-based measures and rating scales

Few studies have systematically assessed executive functioning (EF) skills in boys with XXY, and these are limited by small samples and restricted EF assessment. This study used a broader battery of performance-based measures as well as parent-rating scales of EF in 77 boys and adolescents with XXY (mean age = 12.5 years), recruited from a clinical trial and an outpatient clinic. Exploratory factor analyses were used to create EF domains from performance-based measures, and similar domains were measured using the Behavior Rating Inventory of Executive Function and Conners Parent-Rating Scales. The boys with XXY showed a distinct EF profile, with the greatest deficit in attention and more moderate deficits in working memory, switching, and planning/problem solving. Parent ratings showed similar challenges, as well as impaired inhibition. Independent sample t-tests showed no difference on performance measures between boys diagnosed or not diagnosed with attention-deficit/hyperactivity disorder (ADHD), although parents of boys diagnosed with ADHD reported more difficulties. There were no differences on performance-based tests between those diagnosed pre- and postnatally, although parents of postnatally diagnosed boys reported more metacognitive problems. Language deficits, cognition, and socio-economic status did not account for EF deficits.

Epigenetics and genomics in Klinefelter syndrome

Since the first description of Klinefelter syndrome (KS) was published in 1942 in The Journal of Clinical Endocrinology, large inter-individual variability in the phenotypic presentation has been demonstrated. However, our understanding of the global impact of the additional X chromosome on the genome remains an enigma. Evidence from the existing literature of KS indicates that not just one single genetic mechanism can explain the phenotype and the variable expressivity, but several mechanisms may be at play concurrently. In this review, we describe different genetic mechanisms and recent advances in the understanding of the genome, epigenome, and transcriptome of KS and the link to the phenotype and clinical heterogeneity. Future studies are needed to unite clinical data, genomic data, and basic research attempting to understand the genetics behind KS. Unraveling the genetics of KS will be of clinical relevance as it may enable the use of polygenic risk scores to predict future disease susceptibility and enable clinical risk stratification of KS patients in the future.

Androgens During Infancy, Childhood, and Adolescence: Physiology and Use in Clinical Practice

We provide an in-depth review of the role of androgens in male maturation and development, from the fetal stage through adolescence into emerging adulthood, and discuss the treatment of disorders of androgen production throughout these time periods. Testosterone, the primary androgen produced by males, has both anabolic and androgenic effects. Androgen exposure induces virilization and anabolic body composition changes during fetal development, influences growth and virilization during infancy, and stimulates development of secondary sexual characteristics, growth acceleration, bone mass accrual, and alterations of body composition during puberty. Disorders of androgen production may be subdivided into hypo- or hypergonadotropic hypogonadism. Hypogonadotropic hypogonadism may be either congenital or acquired (resulting from cranial radiation, trauma, or less common causes). Hypergonadotropic hypogonadism occurs in males with Klinefelter syndrome and may occur in response to pelvic radiation, certain chemotherapeutic agents, and less common causes. These disorders all require testosterone replacement therapy during pubertal maturation and many require lifelong replacement. Androgen (or gonadotropin) therapy is clearly beneficial in those with persistent hypogonadism and self-limited delayed puberty and is now widely used in transgender male adolescents. With more widespread use and newer formulations approved for adults, data from long-term randomized placebo-controlled trials are needed to enable pediatricians to identify the optimal age of initiation, route of administration, and dosing frequency to address the unique needs of their patients.

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.

A review of the intriguing interaction between testosterone and neurocognitive development in males with 47,XXY

PURPOSE OF REVIEW

Although 47,XXY (Klinefelter syndrome) was first discovered more than 50 years ago, there have been limited comprehensive studies on this disorder. The present review explains the study of neurodevelopmental dysfunction and the impact of testosterone replacement at specific junctions in the life of males with 47,XXY. The intricate relationship between testosterone, neurodevelopment, health, and well being warrants an in-depth investigation in order to achieve optimal outcomes.

RECENT FINDINGS

Current literature suggests that the implementation of biological treatment has a positive impact on numerous areas of neurodevelopment. Further research is needed to determine ideal dosage, timing, and frequency of biological treatment for efficacy and safety of the child with 47,XXY.

SUMMARY

As noninvasive prenatal screening has detected increasing numbers of fetuses with 47,XXY, parents may benefit from both prenatal and postnatal counseling, including the latest innovative biological treatment, that may further optimize the child's outcome, especially when coupled with targeted early intervention services.

Update On The Clinical Perspectives And Care Of The Child With 47,XXY (Klinefelter Syndrome)

47,XXY (Klinefelter syndrome [KS]) is the most common sex chromosomal aneuploidy (1:660), yet, despite this, only 25% of the males are ever diagnosed. Males with 47,XXY present with characteristic symptoms throughout their lifetime with typical physical and neurodevelopmental manifestations focused in growth, cognitive development, endocrine function, and reproduction. Studies have demonstrated that optimal outcomes are dependent on early detection combined with consistent and targeted neurodevelopmental treatment throughout the lifespan. During infancy and into the preschool years, individuals with 47,XXY commonly face deficits in growth and development in the areas of early hormonal, motor, speech, and behavioral development. As they transition into school, the primary neurodevelopmental concerns include language difficulty, executive dysfunction, behavior, and learning and reading deficits. Adults with 47,XXY often present with taller than average height, low levels of fertility, azoospermia, and elevated gonadotropin levels. These presentations may persist from early childhood through adulthood but can be mitigated by appropriate interventions. Early neurodevelopmental and hormonal treatment has been shown to have a minimizing effect on the physical and neurodevelopmental manifestations in individuals with 47,XXY. With innovative and current research studies, the features common to the neurodevelopmental profile of 47,XXY have been further expanded and defined. Further research is necessary to elucidate and understand the relationship between the brain, behavior, and the phenotypic profile of 47,XXY.

Reversal Learning Performance in the XY∗ Mouse Model of Klinefelter and Turner Syndromes

Klinefelter syndrome (KS; 47, XXY) and Turner syndrome (TS; 45, XO) are caused by two relatively common sex chromosome aneuploidies. These conditions are associated with an increased odds of neuropsychiatric disorders, including attention deficit/hyperactivity disorder (ADHD), as well as impairments in cognition that include learning delays, attentional dysfunction and impulsivity. We studied cognitive functions in the XY^∗ mouse model, which allows comparison of XXY to XY males (KS model), and XO to XX females (TS model). We evaluated adult mice with and without gonads, using a version of an operant reversal-learning task (RLT) that can be used to measure various facets of learning, impulsivity and attention. In the KS model, only one measure related to impulsivity – perseverative responding under reversal conditions – reliably discriminated gonadally intact XXY and XY mice. In contrast, a fundamental learning impairment (more trials to criterion in acquisition phase) in XXY mice, as compared to XY, was observed in gonadectomized subjects. No other task measures showed differences consistent with KS. In the TS mouse model, XO mice did not show a pattern of results consistent with TS, similar to past observations. Thus, the application of this RLT to these XY^∗ models reveals only limited behavioral impairments relevant to KS.

A review of neurocognitive functioning of children with sex chromosome trisomies: Identifying targets for early intervention

Sex chromosome trisomies (SCT) are among the most common chromosomal duplications in humans. Due to recent technological advances in non‐invasive screening, SCT can already be detected during pregnancy. This calls for more knowledge about the development of (young) children with SCT. This review focused on neurocognitive functioning of children with SCT between 0 and 18 years, on domains of global intellectual functioning, language, executive functioning, and social cognition, in order to identify targets that could benefit from early treatment.

Online databases were used to identify peer‐reviewed scientific articles using specific search terms. In total 18 studies were included. When applicable, effect sizes were calculated to indicate clinical significance.

Results of the reviewed studies show that although traditionally, the focus has been on language and intelligence (IQ) in this population, recent studies suggest that executive functioning and social cognition may also be significantly affected already in childhood.

These findings suggest that neuropsychological screening of children diagnosed with SCT should be extended, to also include executive functioning and social cognition. Knowledge about these neurocognitive risks is important to improve clinical care and help identify targets for early support and intervention programs to accommodate for the needs of individuals with SCT.

Neuropsychiatric Aspects in Men with Klinefelter Syndrome

BACKGROUND AND OBJECTIVE

Klinefelter Syndrome (KS) is the most common sex chromosome aneuploidy (47, XXY) and cause of male hypergonadotropic hypogonadism. It is characterized by an extreme clinical heterogeneity in presentation, including infertility, hypogonadism, language delay, metabolic comorbidities, and neurocognitive and psychiatric disorders. Since testosterone is known to have organizational, neurotrophic and neuroprotective effects on brain, the condition of primary hypogonadism could play a role. Moreover, given that KS subjects have an additional X, genes on the extra-chromosome could also exert a significant impact. The aim of this narrative review is to analyze the available literature on the relationship between KS and neuropsychiatric disorders.

METHODS

To extend to the best of published literature on the topic, appropriate keywords and MeSH terms were identified and searched in Pubmed. Finally, references of original articles and reviews were examined.

RESULTS

Both morphological and functional studies focusing on the brain showed that there were important differences in brain structure of KS subjects. Different psychiatric disorders such as Schizophrenia, autism, attention deficit hyperactivity disorder, depression and anxiety were frequently reported in KS patients according to a broad spectrum of phenotypes. T supplementation (TRT) was not able to improve the psychotic disorders in KS men with or without overt hypogonadism.

CONCLUSION

Although the risk of psychosis, depression and autism is increased in subjects with KS, no definitive evidence has been found in studies aiming at identifying the relationship between aneuploidy, T deficit and the risk of psychiatric and cognitive disorders in subjects affected by KS.

Reasoning on Figurative Language: A Preliminary Study on Children with Autism Spectrum Disorder and Klinefelter Syndrome

In this study we explored metaphor and idiom competencies in two clinical populations, children with autistic spectrum disorder (ASD) and children with Klinefelter syndrome (KS), (age range: 9⁻12), compared to typically developing (TD) children of the same age. These three groups were tested with two multiple-choice tests assessing idiom comprehension through iconic and verbal alternatives and a metaphor comprehension test composed of novel, physical-psychological metaphors, requesting verbal explanations. To these instruments, another test was added, assessing basic sentence comprehension. Performances on the different linguistic tasks were examined by means of discriminant analysis which showed that idiom comprehension had a very small weight in distinguishing children with ASD from TD controls, whereas metaphor explanation did distinguish them. This study suggests that figurative language comprehension is not a "core deficit" per se in individuals with ASD. Only when the task requires to explicitly construct and explain a semantic mapping between the two terms of a metaphor does the performance of children with ASD significantly deviate from the typical population. These results are interpreted in terms of a difficulty in children with ASD and KS with complex cognitive and linguistic processes and also in relation with clinical assessment.

A review of neurocognitive functioning and risk for psychopathology in sex chromosome trisomy (47,XXY, 47,XXX, 47, XYY)

PURPOSE OF REVIEW

About one in 650-1000 children is born with an extra X or Y chromosome, referred to as sex chromosome trisomies (SCTs). Studying SCTs may uncover unique insights in neurodevelopmental pathways underlying the risk for neurobehavioral problems and psychopathology. There is also a clinical need for more knowledge about the phenotype of SCT with the recent introduction of noninvasive prenatal screening.

RECENT FINDINGS

The reviewed studies illustrate an increased vulnerability for psychopathology such as (symptoms of) autism spectrum disorder, attention-deficit/hyperactivity disorder, anxiety, depression and, to a lesser degree, psychotic disorders. Although traditionally the primary focus has been on language and learning problems, recent research suggests that impairments in executive functioning, social cognition and emotion regulation may also be key factors underlying the risk for neurobehavioral problems.

SUMMARY

The research field of SCT is in need of a more longitudinal perspective to identify early markers of 'at risk' development, and to assess the effectiveness of early interventions. Neurocognitive markers that signal compromised neurodevelopment may prove to be helpful in this. Variability in the SCT phenotype provides a unique opportunity to identify not only genetic but also environmental factors that shape neurodevelopmental outcome, calling for studies focused on understanding individual differences.

Speech and language in children with Klinefelter syndrome

BACKGROUND

Speech and language deficits are frequent in males with Klinefelter syndrome (KS), yet the research base is slim and specific strengths and deficits in communication have not been well characterised. Nor have studies examined communication abilities across a wide age-range from infancy to adolescence.

OBJECTIVE

To characterise communication in children and adolescents with KS.

METHOD

Twenty-six males, aged 1;1-17;4 years, took part in the study. Oromotor, speech, language, literacy and pragmatic abilities were assessed.

RESULTS

Communication impairment was seen in 92% of cases (24/26), with salient findings being impairments in social-pragmatic language (15/18; 83%), language-memory (12/15; 80%) and literacy (13/17; 76%). Mild to severe receptive and expressive language deficits were common (16/23; 70%), although performance was varied across linguistic domains of semantics, syntax, and morphology. Oromotor impairment (21/21; 100%) and speech impairments were evident from preschool through to adolescence. Whilst speech was highly intelligible (22/26; 85%), articulation errors (12/26; 46%), phonological delay (12/26; 46%), phonological disorder (5/26; 19%) and dysarthria (2/23 8.7%) were observed. Other atypical, yet mild, speech features were noted such as hyponasality (16/23; 70%).

CONCLUSIONS

Language, literacy and social-pragmatic deficits are common in KS. Data suggested a trend for more notable deficits with age and increasing academic and social demands. We added novel data on the nature of speech production deficits, including persistent phonological errors in a number of cases. Earlier detection and intervention of phonological errors may reduce the risk for later language and literacy challenges and optimise academic, and ultimately social and behavioural difficulties later in life.

The incidence of anxiety symptoms in boys with 47,XXY (Klinefelter syndrome) and the possible impact of timing of diagnosis and hormonal replacement therapy

47,XXY (Klinefelter syndrome) is the most common X and Y chromosomal variation (1:660 males). The incidence of anxiety disorders and the impact of hormonal replacement therapy (HRT) is not well understood. Child Behavior Checklist and Screen for Childhood Anxiety Related Emotional Disorders were completed by parents of 80 boys with 47,XXY. Forty received HRT prior to 10 years of age while 40 did not. HRT (22.5%) received early hormonal treatment prior to 18 months. About 32.5% received hormone booster treatment between 5 and 10 years. The remaining 42.5% received both. There were fewer reported social (p = .015), thought (p = .012), and affective problems (p = .048) in treated boys when compared to untreated. Boys with both treatments demonstrated fewer symptoms on anxious/depressed scale (p = .001) compared to those with early treatment only. Within the treated group, prenatally diagnosed showed fewer indications of anxiety problems (p = .02) than their postnatal counterparts. This comparative, cross-sectional study expands previous findings on the possible positive effect of HRT in boys with 47,XXY. Anxiety disorders appear to be a penetrant aspect of the 47,XXY phenotype. Further investigation is warranted to explore the relationship between biological treatment and individual responses to HRT to develop more personalized and precise medicine.

The Association of Motor Skills and Adaptive Functioning in XXY/Klinefelter and XXYY Syndromes

Aims: Klinefelter (XXY) and XXYY syndromes are genetic disorders in males characterized by additional sex chromosomes compared to the typical male karyotype of 46, XY. Both conditions have been previously associated with motor delays and motor skills deficits. We aimed to describe and compare motor skills in males with XXY and XXYY syndromes, and to analyze associations with age, cognitive abilities, and adaptive functioning. Methods: Sixty-four males with XXY and 46 males with XXYY, ages 4-20 were evaluated using the Beery Test of Visual Motor Integration and the Bruininks-Oseretsky Test of Motor Proficiency - 2nd Edition assessments, Vineland-2 adaptive scales, and cognitive testing. Results: Motor coordination impairments were found in 39% of the males with XXY and 73% of the males with XXYY. Both groups showed strengths in visual perceptual skills. Males with XXYY had lower mean scores compared to males with XXY across all assessments. Fine motor dexterity and coordination deficits were common. There was a positive correlation between VMI scores and adaptive functioning. Conclusion: Occupational and physical therapists should be aware of the motor phenotype in XXY and XXYY both to aid in diagnosis of unidentified cases and to guide intervention.

Sex differences in psychiatric disorders: what we can learn from sex chromosome aneuploidies

The study of sexual dimorphism in psychiatric and neurodevelopmental disorders is challenging due to the complex interplay of diverse biological, psychological, and social factors. Males are more susceptible to neurodevelopmental disorders including intellectual disability, autism spectrum disorder, and attention-deficit activity disorder. Conversely, after puberty, females are more prone to major depressive disorder and anxiety disorders compared to males. One major biological factor contributing to sex differences is the sex chromosomes. First, the X and Y chromosomes have unique and specific genetic effects as well as downstream gonadal effects. Second, males have one X chromosome and one Y chromosome, while females have two X chromosomes. Thus, sex chromosome constitution also differs between the sexes. Due to this complexity, determining genetic and downstream biological influences on sexual dimorphism in humans is challenging. Sex chromosome aneuploidies, such as Turner syndrome (X0) and Klinefelter syndrome (XXY), are common genetic conditions in humans. The study of individuals with sex chromosome aneuploidies provides a promising framework for studying sexual dimorphism in neurodevelopmental and psychiatric disorders. Here we will review and contrast four syndromes caused by variation in the number of sex chromosomes: Turner syndrome, Klinefelter syndrome, XYY syndrome, and XXX syndrome. Overall we describe an increased rate of attention-deficit hyperactivity disorder and autism spectrum disorder, along with the increased rates of major depressive disorder and anxiety disorders in one or more of these conditions. In addition to contributing unique insights about sexual dimorphism in neuropsychiatric disorders, awareness of the increased risk of neurodevelopmental and psychiatric disorders in sex chromosome aneuploidies can inform appropriate management of these common genetic disorders.

DNA hypermethylation and differential gene expression associated with Klinefelter syndrome

Klinefelter syndrome (KS) has a prevalence ranging from 85 to 250 per 100.000 newborn boys making it the most frequent sex chromosome aneuploidy in the general population. The molecular basis for the phenotypic traits and morbidity in KS are not clarified. We performed genome-wide DNA methylation profiling of leucocytes from peripheral blood samples from 67 KS patients, 67 male controls and 33 female controls, in addition to genome-wide RNA-sequencing profiling in a subset of 9 KS patients, 9 control males and 13 female controls. Characterization of the methylome as well as the transcriptome of both coding and non-coding genes identified a unique epigenetic and genetic landscape of both autosomal chromosomes as well as the X chromosome in KS. A subset of genes show significant correlation between methylation values and expression values. Gene set enrichment analysis of differentially methylated positions yielded terms associated with well-known comorbidities seen in KS. In addition, differentially expressed genes revealed enrichment for genes involved in the immune system, wnt-signaling pathway and neuron development. Based on our data we point towards new candidate genes, which may be implicated in the phenotype and further point towards non-coding genes, which may be involved in X chromosome inactivation in KS.

Beyond the Literal Meaning of Words in Children with Klinefelter Syndrome: Two Case Studies

Literature on children with Klinefelter Syndrome (KS) points to general linguistic difficulties in both comprehension and production among other cognitive functions, and in the majority of cases, these coexist with an intellectual level within the norms. In these conditions, children having language delay generally engage in language therapy and are systematically monitored across ages. In this article, we present the profiles of two children with KS (47, XXY), aged 9.1 (Child S) and 13 (Child D), whose language development was assessed as adequate at age 3, and for this reason, did not receive any language treatment. At the present stage, their IQ, as measured by Wechsler Scales (Child S: 92; Child D: 101), is within the norm, but they both present marked weaknesses in pragmatic skills such as figurative language comprehension. The analysis of these two cases points to the need to go beyond global indexes of verbal abilities, as the same global index may mask a wide diversification of individual profiles. In addition, this study underlines the importance of monitoring the developmental trajectories of children like Child D and Child S, because weaknesses in pragmatic skills that are relevant for both academic achievement and social adaptation could emerge at later stages.

Klinefelter syndrome: more than hypogonadism

Klinefelter syndrome (KS) is the most frequent chromosome disorder in males (1:650 newborn males), defined by 47,XXY karyotype. The classical phenotype is that of a tall male with relatively long legs, small, firm testes and gynecomastia. Azoospermia and infertility are almost inevitably present, but may be overcome by TESE and ICSI. Nevertheless, a broad spectrum of phenotypes has been described and more than 70% of the actually existing KS men may remain undiagnosed throughout their lifespan. Accordingly, hypogonadism is usually not evident until early adulthood and progresses with ageing. KS patients present a series of comorbidities that increase morbidity and mortality by 40%. Such disturbances are the impaired metabolic profile (obesity, dyslipidemia, insulin resistance) and a tendency to thrombosis, which all favor cardiovascular disease. They also present susceptibility for specific neoplasias (breast cancer, extragonadal germ cell tumors), autoimmune diseases as well as osteoporosis and bone fractures. Moreover, KS has been associated with verbal processing and attention deficits as well as social skill impairments, leading KS individuals to academic and professional achievements inferior to those of their peers of comparable socio-economic status. Nevertheless, the majority fall within the average range regarding their intellectual abilities and adaptive functioning. Testosterone replacement therapy (TRT) is the mainstay of treatment in hypogonadal KS patients; however, randomized trials are needed to determine optimal therapeutic regimens and follow-up schedules.

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.

Rapid screening for Klinefelter syndrome with a simple high-resolution melting assay: a multicenter study

Klinefelter syndrome (KS) is the set of symptoms that result from the presence of an extra X chromosome in males. Postnatal population-based KS screening will enable timely diagnosis of this common chromosomal disease, providing the opportunity for early intervention and therapy at the time point when they are most effective and may prevent later symptoms or complications. Therefore, through this study, we introduced a simple high-resolution melting (HRM) assay for KS screening and evaluated its clinical sensitivity and specificity in three medical centers using 1373 clinical blood samples. The HRM assay utilized a single primer pair to simultaneously amplify specific regions in zinc finger protein, X-linked (ZFX) and zinc finger protein, Y-linked (ZFY). In cases of KS, the ratios of ZFX/ZFY are altered compared to those in normal males. As a result, the specific melting profiles differ and can be differentiated during data analysis. This HRM assay displayed high analytical specificity over a wide range of template DNA amounts (5 ng–50 ng) and reproducibility, high resolution for detecting KS mosaicism, and high clinical sensitivity (100%) and specificity (98.1%). Moreover, the HRM assay was rapid (2 h per run), inexpensive (0.2 USD per sample), easy to perform and automatic, and compatible with both whole blood samples and dried blood spots. Therefore, this HRM assay is an ideal postnatal population-based KS screening tool that can be used for different age groups.