Klinefelter syndrome and its variants: an update and review for the primary pediatrician

Testicular Dysfunction in 47,XXY Boys: When It All Begins. A Semilongitudinal Study

OBJECTIVE

Klinefelter syndrome is the most common chromosomal disorder in males and the most common cause of hypergonadotropic hypogonadism. We describe the natural history of testicular dysfunction in patients with Klinefelter syndrome through the integration of clinical, hormonal, and quantitative ultrasound data in a life-course perspective.

DESIGN

Prospective semilongitudinal study.

METHODS

We included 155 subjects with 47,XXY karyotype (age range: 7 months-55 years) naïve to testosterone replacement therapy. Subjects were divided according to pubertal stage and age group (transition age and adults). Serial clinical, hormonal, and testicular ultrasound (US) assessments were performed.

RESULTS

Testicular development progresses until Tanner stage 4, with subsequent regression, whereas Sertoli and germ cell impairment is not hormonally detected before Tanner stages 3-4, as reflected by normal inhibin B values until stage 4 and the fall in the inhibin B/follicle-stimulating hormone ratio thereafter. The testosterone/luteinizing hormone ratio peaks during Tanner stages 2-3 and declines from Tanner stage 4 onward, preceding the development of overt hypogonadism. US echotexture progressively worsens until transition age, reflecting ongoing gonadal compromise, whereas quantitative US echotexture measures and the presence of both hypoechoic lesions and microlithiasis independently and significantly predict a lower circulating testosterone level.

CONCLUSIONS

The findings from this large prospective study contribute to our understanding of the natural history of testicular dysfunction in Klinefelter syndrome, underlining the importance of quantitative testicular US in infancy and childhood, as well as during pubertal development and transition age, for the optimal care of Klinefelter syndrome patients.

Klinefelter Syndrome: What should we tell prospective parents?

Klinefelter syndrome (KS) or 47,XXY is the most common sex chromosome aneuploidy (SCA), occurring at a prevalence of 1 in 600 male pregnancies. Historically, only 25% of individuals with KS came to medical attention, for a range of issues across the life course including under-virilisation at birth, developmental and social concerns in childhood, absence, delay or arrest of puberty in adolescence or infertility in adulthood. Our understanding of the phenotypic spectrum of KS has been largely influenced by this ascertainment bias. With increasing uptake of antenatal noninvasive prenatal testing (NIPT), a corresponding increase in identification of KS has been documented. Population-based longitudinal data from infancy to adulthood on these individuals is lacking, which impedes balanced antenatal genetic counselling and raises issues for prospective parents and clinicians alike.

Beta Thalassemia and Klinefelter syndrome: a rare occurrence

Background

β-Thalassemia is an inherited haematological blood disorder in the HBB gene, and variations in this HBB gene lead to the absence/deficiency of the Beta chain synthesis of haemoglobin leading to severe anaemia. Klinefelter syndrome is a chromosomal abnormality that affects physical and cognitive development in males. Affected individuals are taller, show gynaecomastia and behavioural problems and have small testes that do not produce much testosterone. We describe a boy with β-Thalassemia major referred for chromosomal analysis due to delayed puberty and short stature. This is a second case reported in the literature that gives information on two different contradicting genetic disorders in a single individual but novel case as he exhibits additional short-stature phenotype.

Case presentation

A 17-year-old boy with short stature and gonadal dysfunction was referred for chromosomal analysis. He needed blood transfusion every 4 weeks. The GTG banding for chromosomal analysis and standard PCR for variant detection of HBB gene, Bi-directional Sanger sequencing of the PCR products and multiplex PCR for Y microdeletion of the AZF a, b and c regions on the Y chromosome were performed. The cytogenetic analysis revealed a karyotype of 47,XXY. The HBB gene detected two heterozygous variants forming a pathogenic compound heterozygous condition. The multiplex PCR revealed that the AZF a, b and c regions were intact and were not deleted.

Conclusion

To our knowledge, this is the second case of a patient with β-Thalassemia associated with Klinefelter syndrome but a novel case with short-stature phenotype association instead of tall stature. The possible association of these two disorders and the unusual phenotypic presentation are discussed. This study highlights the possibility of ruling out Thalassemia while evaluating patients with short stature and delayed puberty.

Non-organ-specific autoimmunity in adult 47,XXY Klinefelter patients and higher-grade X-chromosome aneuploidies

Current literature regarding systemic autoimmune diseases in X-chromosome aneuploidies is scarce and limited to case reports. Our aim was to evaluate the frequency of anti-nuclear (ANAs), extractable nuclear (ENA), anti-double-stranded DNA (dsDNAs), anti-smooth muscle (ASMAs) and anti-mitochondrial (AMAs) antibodies in a large cohort of adults with Klinefelter's syndrome (KS, 47,XXY) and rare higher-grade sex chromosome aneuploidies (HGAs) for the first time. Sera from 138 X-chromosome aneuploid patients [124 adult patients with 47,XXY KS and 14 patients with HGA (six children, eight adults)] and 50 age-matched 46,XY controls were recruited from the Sapienza University of Rome (2007-17) and tested for ANAs, ENAs, anti-dsDNAs, ASMAs and AMAs. Non-organ-specific immunoreactivity was found to be significantly higher in patients with 47,XXY KS (14%) than in the controls (2%, p = 0.002). Among all the antibodies investigated, only ANAs were observed significantly more frequently in patients with 47,XXY KS (12.1%) than in the controls (2%, p = 0.004). No anti-dsDNA immunoreactivity was found. Stratifying by testosterone replacement therapy (TRT), non-organ-specific autoantibody frequencies were higher in TRT-naive (p = 0.01) and TRT-treated groups than in controls. No patients with HGA were found positive for the various autoantibodies. Non-organ-specific autoantibodies were significantly present in 47,XXY adult patients. Conversely, HGAs did not appear to be target of non-organ-specific immunoreactivity, suggesting that KS and HGAs should be considered as two distinct conditions. The classification and diagnosis of systemic autoimmune diseases is frequently difficult. To support a correct clinical evaluation of KS disease and to prevent eventual secondary irreversible immune-mediated damages, we highlight the importance of screening for non-organ-specific autoimmunity in Klinefelter's syndrome.

From mini-puberty to pre-puberty: early impairment of the hypothalamus-pituitary-gonadal axis with normal testicular function in children with non-mosaic Klinefelter syndrome

PURPOSE

Klinefelter syndrome (KS) is a genetic disorder caused by the presence of an extra X chromosome in males. The aim of this study was to evaluate the hypothalamic-pituitary-gonadal (HPG) axis and the clinical profile of KS boys from mini-puberty to early childhood.

PATIENTS AND METHODS

In this retrospective, cross-sectional, population study, 145 KS boys and 97 controls aged 0-11.9 years were recruited. Serum FSH, LH, testosterone (T), Inhibin B (INHB), sex hormone binding globulin (SHBG) and anti-Müllerian hormone (AMH) were determined. Auxological parameters were assessed. To better represent the hormonal and clinical changes that appear in childhood, the entire population was divided into 3 groups: ≤ 6 months (group 1; mini-puberty); > 6 months and ≤ 8 years (group 2; early childhood); > 8 and ≤ 12 years (group 3; mid childhood).

RESULTS

During mini-puberty (group 1), FSH and LH were significantly higher in KS infants than controls (p < 0.05), as were INHB and T (respectively p < 0.0001 and p < 0.005). INHB was also significantly higher in KS than controls in group 2 (p < 0.05). AMH appeared higher in KS than in controls in all groups, but the difference was only statistically significant in group 2 (p < 0.05). No significant differences were found in height, weight, testicular volume, and penile length.

CONCLUSIONS

No hormonal signs of tubular or interstitial damage were found in KS infants. The presence of higher levels of gonadotropins, INHB and testosterone during mini-puberty and pre-puberty may be interpreted as an alteration of the HPG axis in KS infants.

Ontogeny of Hypothalamus-Pituitary Gonadal Axis and Minipuberty: An Ongoing Debate?

The fetal hypothalamus-pituitary gonadal (HPG) axis begins to function during mid-gestation but its activity decreases during late pregnancy due to the suppressive effects of placental estrogens. Placental hormones drop immediately after birth, FSH and LH surge at around 1 week and peak between 1 and 3 months of life. The HPG axis is activated in both sexes, but a sexual dimorphism is evident with higher LH values in boys, while FSH prevails in girls. Both gonadotrophins decline in boys by around 6 months of age. In girls, LH declines at the same time as in boys, while FSH persists elevated up to 3 or 4 years of age. As a result of gonadotropin activation, testicular testosterone increases in males and ovarian estradiol rises in females. These events clinically translate into testicular and penile growth in boys, enlargement of uterus and breasts in girls. The functional impact of HPG axis activity in infancy on later reproductive function is uncertain. According to the perinatal programming theory, this period may represent an essential programming process. In boys, long-term testicular hormonal function and spermatogenesis seem to be, at least in part, regulated by minipuberty. On the contrary, the role of minipuberty in girls is still uncertain. Recently, androgen exposure during minipuberty has been correlated with later sex-typed behavior. Premature and/or SGA infants show significant differences in postnatal HPG axis activity in comparison to full-term infants and the consequences of these differences on later health and disease require further research. The sex-dimorphic HPG activation during mid-gestation is probably responsible for the body composition differences observed ad birth between boys and girls, with boys showing greater total body mass and lean mass, and a lower proportion of fat mass. Testosterone exposure during minipuberty further contributes to these differences and seems to be responsible for the significantly higher growth velocity observed in male infants. Lastly, minipuberty is a valuable "window of opportunity" for differential diagnosis of disorders of sex development and it represents the only time window before puberty when congenital hypogonadism can be diagnosed by the simple analysis of basal gonadotropin and gonadal hormone levels.

The X chromosome and male infertility

The X chromosome is a key player in germ cell development, as has been highlighted for males in previous studies revealing that the mammalian X chromosome is enriched in genes expressed in early spermatogenesis. In this review, we focus on the X chromosome’s unique biology as associated with human male infertility. Male infertility is most commonly caused by spermatogenic defects to which X chromosome dosage is closely linked; for example, any supernumerary X chromosome as in Klinefelter syndrome will lead to male infertility. Furthermore, because males normally only have a single X chromosome and because X-linked genetic anomalies are generally only present in a single copy in males, any loss-of-function mutations in single-copy X-chromosomal genes cannot be compensated by a normal allele. These features make X-linked genes particularly attractive for studying male spermatogenic failure. However, to date, only very few genetic causes have been identified as being definitively responsible for male infertility in humans. Although genetic studies of germ cell-enriched X-chromosomal genes in mice suggest a role of certain human orthologs in infertile men, these genes in mice and humans have striking evolutionary differences. Furthermore, the complexity and highly repetitive structure of the X chromosome hinder the mutational analysis of X-linked genes in humans. Therefore, we conclude that additional methodological approaches are urgently warranted to advance our understanding of the genetics of X-linked male infertility.

Perspectives of adults with Klinefelter syndrome, unaffected adolescent males, and parents of affected children toward diagnosis disclosure: a Thai experience

Little is known about disclosure of diagnosis to males with Klinefelter syndrome (KS) diagnosed before birth or during childhood, especially in Asian context. Insufficient preparation for disclosure communication could lead to the child's depression, anxiety, or disrupted self-esteem. This is an interventional and qualitative interview study with a brief self-reported survey. The study consists of three phases. In phase I, adults with KS were asked about their experiences and viewpoints toward KS disclosure and diagnosis through individual interviews. In phase II, unaffected adolescent males were given information about KS and then asked to give hypothetical answers to a questionnaire followed by a group interview, as if they had KS. In phase III, parents of children with KS were asked to complete a questionnaire followed by a group interview which included a discussion about their disclosure plans and their concerns. The parents were provided information obtained from adults with KS and unaffected adolescent males, and were then interviewed again as a group. We found that the most hurtful issues were discovering their infertility from KS and late disclosure. From the perspective of unaffected adolescent males, early disclosure in early or mid-teens in a neutral, supportive, and relaxed manner, along with information on benefits of hormonal treatment, the assurance of biological sex as "male," and avoidance of some sensitive words are strongly recommended, as a way to promote self-confidence and positive coping with the diagnosis. After intervention, the parents reported more confidence and less anxiety about disclosing the diagnosis to their children, and indicated that they would disclose KS at an earlier age. For unaffected adolescent males, though it is a hypothetical scenario and their reaction may differ from affected adolescents, unaffected adolescent males' viewpoints on how they might react are more or less representative of cultural changes for the new generation, especially in the Asian context. In addition, their viewpoints influenced parents' decision and genetic counseling plans for the diagnosis disclosure of KS to their children. We propose a preliminary guideline for KS diagnosis disclosure.

Endocrine and metabolic evaluation of classic Klinefelter syndrome and high-grade aneuploidies of sexual chromosomes with male phenotype: are they different clinical conditions?

OBJECTIVE

Klinefelter syndrome (KS) is the most common sex chromosome aneuploidy in males. As well as classic KS, less frequent higher-grade aneuploidies (HGAs) are also possible. While KS and HGAs both involve testicular dysgenesis with hypergonadotropic hypogonadism, they differ in many clinical features. The aim of this study was to investigate the endocrinal and metabolic differences between KS and HGAs.

DESIGN

Cross-sectional, case-control study.

METHODS

88 patients with KS, 24 with an HGA and 60 healthy controls. Given the known age-related differences all subjects were divided by age into subgroups 1, 2 and 3. Pituitary, thyroid, gonadal and adrenal functions were investigated in all subjects. Metabolic aspects were only evaluated in subjects in subgroups 2 and 3.

RESULTS

FT4 and FT3 levels were significantly higher in HGA than in KS patients in subgroups 1 and 2; in subgroup 3, FT4 was significantly higher in controls than in patients. Thyroglobulin was significantly higher in HGA patients in subgroup 1 than in KS patients and controls. Hypergonadotropic hypogonadism was confirmed in both KS and HGA patients, but was more precocious in the latter, as demonstrated by the earlier increase in gonadotropins and the decrease in testosterone, DHEA-S and inhibin B. Prolactin was significantly higher in HGA patients, starting from subgroup 2. Total and LDL cholesterol were significantly higher in HGA patients than in KS patients and controls, while HDL cholesterol was higher in controls than in patients.

CONCLUSIONS

KS and HGAs should be considered as two distinct conditions.

MECHANISMS IN ENDOCRINOLOGY: Aberrations of the X chromosome as cause of male infertility

Male infertility is most commonly caused by spermatogenetic failure, clinically noted as oligo- or a-zoospermia. Today, in approximately 20% of azoospermic patients, a causal genetic defect can be identified. The most frequent genetic causes of azoospermia (or severe oligozoospermia) are Klinefelter syndrome (47,XXY), structural chromosomal abnormalities and Y-chromosomal microdeletions. Consistent with Ohno's law, the human X chromosome is the most stable of all the chromosomes, but contrary to Ohno's law, the X chromosome is loaded with regions of acquired, rapidly evolving genes, which are of special interest because they are predominantly expressed in the testis. Therefore, it is not surprising that the X chromosome, considered as the female counterpart of the male-associated Y chromosome, may actually play an essential role in male infertility and sperm production. This is supported by the recent description of a significantly increased copy number variation (CNV) burden on both sex chromosomes in infertile men and point mutations in X-chromosomal genes responsible for male infertility. Thus, the X chromosome seems to be frequently affected in infertile male patients. Four principal X-chromosomal aberrations have been identified so far: (1) aneuploidy of the X chromosome as found in Klinefelter syndrome (47,XXY or mosaicism for additional X chromosomes). (2) Translocations involving the X chromosome, e.g. nonsyndromic 46,XX testicular disorders of sex development (XX-male syndrome) or X-autosome translocations. (3) CNVs affecting the X chromosome. (4) Point mutations disrupting X-chromosomal genes. All these are reviewed herein and assessed concerning their importance for the clinical routine diagnostic workup of the infertile male as well as their potential to shape research on spermatogenic failure in the next years.

Muscle Weakness: A Misleading Presentation in Children With Distinctive Syndromic Entities (Clinical Case Reports)

Marked ligamentous hyperlaxity and muscle weakness/wasting associated with awkward gait are the main deficits confused with the diagnosis of myopathy. Seven children (6 boys and 1 girl with an average age of 8 years) were referred to our department because of diverse forms of skeletal abnormalities. No definitive diagnosis was made, and all underwent a series of sophisticated investigations in other institutes in favor of myopathy. We applied our methodology through the clinical and radiographic phenotypes followed by targeted genotypic confirmation. Three children (2 boys and 1 girl) were compatible with the diagnosis of progressive pseudorheumatoid chondrodysplasia. The genetic mutation was correlated with the WISP 3 gene actively expressed by articular chondrocytes and located on chromosome 6. Klinefelter syndrome was the diagnosis in 2 boys. Karyotyping confirmed 47,XXY (aneuploidy of Klinefelter syndrome). And 2 boys were finally diagnosed with Morquio syndrome (MPS type IV A) as both showed missense mutations in the N-acetylgalactosamine-sulfate sulfatase gene. Misdiagnosis can lead to the initiation of a long list of sophisticated investigations.

Obesity and Hyperglycemia in Korean Men with Klinefelter Syndrome: The Korean Endocrine Society Registry

BACKGROUND

The aim of this study was to investigate the prevalence of obesity in Korean men with Klinefelter syndrome (KS) and the associated risk factors for obesity and hyperglycemia.

METHODS

Data were collected retrospectively from medical records from 11 university hospitals in Korea between 1994 and 2014. Subjects aged ≥18 years with newly diagnosed KS were enrolled. The following parameters were recorded at baseline before treatment: chief complaint, height, weight, fasting glucose level, lipid panel, blood pressure, testosterone, luteinizing hormone, follicle-stimulating hormone, karyotyping patterns, and history of hypertension, diabetes, and dyslipidemia.

RESULTS

Data were analyzed from 376 of 544 initially enrolled patients. The rate of the 47 XXY chromosomal pattern was 94.1%. The prevalence of obesity (body mass index ≥25 kg/m²) in Korean men with KS was 42.6%. The testosterone level was an independent risk factor for obesity and hyperglycemia.

CONCLUSION

Obesity is common in Korean men with KS. Hypogonadism in patients with KS was associated with obesity and hyperglycemia.

Anatomical and clinical aspects of Klinefelter's syndrome

Klinefelter's syndrome, the most common sex disorder associated with chromosomal aberrations, is characterized by a plethora of clinical features. Parameters for diagnosis of the syndrome are constantly expanding as new anatomical and hormonal abnormalities are noted, yet Klinefelter's remains underdiagnosed and underreported. This review outlines the key anatomical characteristics associated with the syndrome, which are currently used for clinical diagnosis, or may provide means for improving diagnosis in the future. Clin. Anat. 29:606-619, 2016. © 2016 Wiley Periodicals, Inc.

The eXtraordinarY Kids Clinic: an interdisciplinary model of care for children and adolescents with sex chromosome aneuploidy

Purpose

Individuals with sex chromosome aneuploidies (SCAs) are born with an atypical number of X and/or Y chromosomes, and present with a range of medical, developmental, educational, behavioral, and psychological concerns. Rates of SCA diagnoses in infants and children are increasing, and there is a need for specialized interdisciplinary care to address associated risks. The eXtraordinarY Kids Clinic was established to provide comprehensive and experienced care for children and adolescents with SCA, with an interdisciplinary team composed of developmental–behavioral pediatrics, endocrinology, genetic counseling, child psychology, pediatric neuropsychology, speech–language pathology, occupational therapy, nursing, and social work. The clinic model includes an interdisciplinary approach to care, where assessment results by each discipline are integrated to develop unified diagnostic impressions and treatment plans individualized for each patient. Additional objectives of the eXtraordinarY Kids Clinic program include prenatal genetic counseling, research, education, family support, and advocacy.

Methods

Satisfaction surveys were distributed to 496 patients, and responses were received from 168 unique patients.

Results

Satisfaction with the overall clinic visit was ranked as “very satisfied” in 85%, and as “satisfied” in another 9.8%. Results further demonstrate specific benefits from the clinic experience, the importance of a knowledgeable clinic coordinator, and support the need for similar clinics across the country. Three case examples of the interdisciplinary approach to assessment and treatment are included.

Do X-linked diseases affect periodontal health?

Genetic factors play an important etiologic role in destructive periodontal diseases. There have been reports that sex chromosomes, especially disorders associated with the X chromosome, affect periodontal health. Although numerous X-linked diseases have been reported to be associated with various periodontal diseases, the association of gingivitis and/or periodontitis with these genetic syndromes should be considered tenuous and raises the question of whether the periodontal manifestation truly arises from an underlying X-linked genetic etiology. A brief overview of genetics in relation to sex chromosomes and putative X-linked genetic periodontal diseases is given.

Key Diagnostic Finding in a Condition with Variable Clinical Presentations

This is an interesting case series on a very common genetic condition which are often diagnosed late as clinical signs are inconspicuous. We would like to highlight the principal clinical examination finding which led to diagnosis.

It's not all about the testes: medical issues in Klinefelter patients

Important medical conditions associated with Klinefelter syndrome (KS) are categorized as: 1) motor, cognitive, and behavioral dysfunction; 2) tumors; 3) vascular disease; and 4) endocrine/metabolic and autoimmune diseases. Earlier diagnosis of KS may lead to earlier intervention with effective treatment.

X-chromosome dosage affects male sexual behavior

Sex differences in the brain and behavior are primarily attributed to dichotomous androgen exposure between males and females during neonatal development, as well as adult responses to gonadal hormones. Here we tested an alternative hypothesis and asked if sex chromosome complement influences male copulatory behavior, a standard behavior for studies of sexual differentiation. We used two mouse models with non-canonical associations between chromosomal and gonadal sex. In both models, we found evidence for sex chromosome complement as an important factor regulating sex differences in the expression of masculine sexual behavior. Counter intuitively, males with two X-chromosomes were faster to ejaculate and display more ejaculations than males with a single X. Moreover, mice of both sexes with two X-chromosomes displayed increased frequencies of mounts and thrusts. We speculate that expression levels of a yet to be discovered gene(s) on the X-chromosome may affect sexual behavior in mice and perhaps in other mammals.

Advances in whole-genome genetic testing: from chromosomes to microarrays

Whole-genome genetic diagnostics has changed the clinical landscape of pediatric and adolescent medicine. In this article, we review the history of clinical cytogenetics as the field has progressed from studying chromosomes prepared from cells squashed between 2 slides to the high-resolution, whole-genome technology in use today, which has allowed for the identification of numerous previously unrecognized microdeletion and microduplication syndromes. Types of arrays and the data they collect are addressed, as are the types of results that array comparative genomic hybridization studies may generate. Throughout the review, we present case stories to illustrate the familiar (Down syndrome) and the new (a never-before reported microdeletion on the long arm of chromosome 12).

Chromosomal variants in klinefelter syndrome

Klinefelter syndrome (KS) describes the phenotype of the most common sex chromosome abnormality in humans and occurs in one of every 600 newborn males. The typical symptoms are a tall stature, narrow shoulders, broad hips, sparse body hair, gynecomastia, small testes, absent spermatogenesis, normal to moderately reduced Leydig cell function, increased secretion of follicle-stimulating hormone, androgen deficiency, and normal to slightly decreased verbal intelligence. Apart from that, amongst others, osteoporosis, varicose veins, thromboembolic disease, or diabetes mellitus are observed. Some of the typical features can be very weakly pronounced so that the affected men often receive the diagnosis only at the adulthood by their infertility. With a frequency of 4%, KS is described to be the most common genetic reason for male infertility. The most widespread karyotype in affected patients is 47,XXY. Apart from that, various other karyotypes have been described, including 46,XX in males, 47,XXY in females, 47,XX,der(Y), 47,X,der(X),Y, or other numeric sex chromosome abnormalities (48,XXXY, 48,XXYY, and 49,XXXXY). The focus of this review was to abstract the different phenotypes, which come about by the various karyotypes and to compare them to those with a 'normal' KS karyotype. For that the patients have been divided into 6 different groups: Klinefelter patients with an additional isochromosome Xq, with additional rearrangements on 1 of the 2 X chromosomes or accordingly on the Y chromosome, as well as XX males and true hermaphrodites, 47,XXY females and Klinefelter patients with other numeric sex chromosome abnormalities. In the latter, an almost linear increase in height and developmental delay was observed. Men with an additional isochromosome Xq show infertility and other minor features of 'normal' KS but not an increased height. Aside from the infertility, in male patients with other der(X) as well as der(Y) rearrangements and in XXY women no specific phenotype is recognizable amongst others due to the small number of cases. The phenotype of XX males depends on the presence of SRY (sex-determining region Y) and the level of X inactivation at which SRY-negative patients are generally rarely observed.

Penile anthropometry in systemic lupus erythematosus patients

The aim of this study was to evaluate penile anthropometry in systemic lupus erythematosus (SLE) patients compared with healthy controls and the possible relevant pubertal, clinical, hormonal and treatment factors that could influence penile dimensions. Twenty-five consecutive SLE patients were assessed by urological examination, sexual function, testicular ultrasound, hormones, sperm analysis, genetic analysis, clinical features and treatment. The control group included 25 age-matched healthy males. SLE patients had a lower median penis length and circumference [8 (7.5–10) vs. 10 (8–13) cm, p = 0.0001; 8 (7–10) vs. 10 (7–11) cm, p = 0.001; respectively], lower median testicular volume by right and left Prader [15 (10–25) vs. 20 (12–25) ml, p = 0.003; 15 (10–25) vs. 20 (12–25) ml, p = 0.006; respectively], higher median of follicle-stimulating hormone [5.8 (2.1–25) vs. 3.3 (1.9–9) IU/l, p = 0.002] and lower morning total testosterone levels (28% vs. 0%, p = 0.009) compared with controls. In spite of that, erectile dysfunction was not observed in patients or controls. Analyses of lupus patients revealed that the median penis circumference was lower in patients with disease onset before first ejaculation compared with those with disease onset after first ejaculation [7.8 (7–10) vs. 9.0 (7.5–10) cm, p = 0.026]. No differences were observed in the median penile anthropometry regarding sexual dysfunction ( p = 0.610), lower morning total testosterone levels ( p = 0.662), oligo/azoospermia ( p = 0.705), SLE Disease Activity Index ≥ 4 ( p = 0.562), Systemic Lupus International Collaborating Clinics/ACR Damage Index ≥ 1 ( p = 0.478), prednisone cumulative dose ( p = 0.789) and intravenous cyclophosphamide therapy ( p = 0.754). Klinefelteŕs syndrome (46XY/47XXY) was diagnosed in one (4%) SLE patient with decreased penile size whereas Y-chromosomal microdeletions was absent in all of them. In conclusion, we have identified reduced penile dimensions in SLE patients with no deleterious effect in erectile function. Disease onset before first ejaculation seems to affect penis development in pre-pubertal lupus.

[35-year old patient with severe thromboembolism]

We report a case of a 35 year old male with severe deep vein thrombosis of the lower limb on both sides and pulmonary embolism. A Klinefelter's mosaic (47,XXY [81%]/48,XXXY [19%]) was diagnosed. Because no other cause for this thromboembolism was found, we assume that in part, it was caused by the Klinefelter's mosaic. In all male patients presenting with thromboembolism, especially those with an unusual habitus, a Klinefelter's syndrome should be considered as differential diagnosis. Testosterone substitution therapy should be started in all patients with Klinefelter's syndrome to prevent further disease.

Clinical variability and novel neurodevelopmental findings in 49, XXXXY syndrome

49, XXXXY is a rare chromosomal syndrome due to double nondisjunction of the replicating X chromosome. Considered a severe variant of XXY or Klinefelter syndrome, boys with this chromosome constitution are assumed to have severe mental retardation (MR) in addition to craniofacial, genital, endocrine, and heart abnormalities. Here, we present a multidisciplinary analysis including the clinical and neurobehavioral aspects of this condition in 20 boys with 49, XXXXY who share a common phenotype and neurobehavioral profile. The phenotypic presentation of the boys with 49, XXXXY shares some characteristics with 47, XXY, but there are also other unique and distinctive features. Previously unappreciated intact nonverbal skills are evident in conjunction with moderate to severe developmental dyspraxia. Variability in clinical and cognitive functioning may reflect skewed X inactivation, mosaicism, or other factors that warrant further investigation.

Neural correlates of error monitoring in an adult with Klinefelter's syndrome: a case report

Studies have indicated that individuals with Klinefelter's syndrome (KS) exhibit deficits in executive functions. However, little attention has been paid to investigate control mechanism of executive functions, i.e., error monitoring, in individuals with KS. Two event-related potential (ERP) components, i.e., error-related negativity (Ne/ERN) and error positivity (Pe), are the electrophysiological markers of error monitoring. This case report presents the findings of error monitoring from an adult with KS using the electrophysiological technique. This KS individual displayed small ERN and Pe amplitudes, suggesting that he may exhibit deficient error detection and reaction, a lack of conscious error recognition, and nonproficient adjustment after an error. The findings of this report should stimulate further study in error monitoring in individuals with KS.

Strategies and advantages of early diagnosis in Klinefelter's syndrome

Nearly 70 years after its description, Klinefelter's syndrome (KS) remains a largely undiagnosed condition. In addition to its typical characteristics of increased follicle-stimulating hormone secretion and small and firm testes, the syndrome presents an extremely wide spectrum of phenotypes. This could be explained by the possible presence of chromosomal mosaicism, androgen receptor polymorphisms and related heterogeneous endocrine abnormalities. The varied but relatively mild physical abnormalities also explain why many patients do not receive clinical attention until adulthood, when they seek medical advice on small testes or infertility. Diagnosis is also hindered by the low awareness of the disease among health professionals. This paper aims to review the possible signs of KS at different stages of life that could help achieve an early (or at least earlier) diagnosis. It has been demonstrated that the early diagnosis of KS improves patients' quality of life and enables better medical treatment. To achieve this, it is crucial to increase both medical and general awareness of the disease, including through use of the media and patients' associations.

Cleft palate in a rare case of Variant Klinefelter syndrome with 48,XXXY/46,XY mosaicism

Variant Klinefelter syndrome with 48,XXXY/46,XY mosaicism has been rarely reported, and its phenotypic features, compared with those of the classic type, have not been well delineated. We describe a newborn baby with phenotypic abnormalities, including cleft palate and low-set ears. The cytogenetic analysis of peripheral blood lymphocytes showed a karyotype of 48,XXXY[36]/46,XY[4]. To the best of our knowledge, this is the first case in which 48,XXXY/46,XY mosaicism was related to the congenital anomaly of cleft palate. This case underscores that cytogenetic analysis should be a mandatory workup for the patient with cleft palate and that cleft palate may be a rare clinical presentation of the variant Klinefelter syndrome.

Social function in multiple X and Y chromosome disorders: XXY, XYY, XXYY, XXXY

Klinefelter syndrome (47,XXY) was initially described in the context of its endocrinologic and physical features; however, subsequent studies have revealed specific impairments in verbal skills and social functioning. Males with sex chromosomal aneuploidies are known to have variability in their developmental profile with the majority presenting with expressive language deficits. As a consequence of language delays, they have an increased likelihood of language-based learning disabilities and social-emotional problems that may persist through adulthood. Studies on males with 47,XXY have revealed unique behavioral and social profiles with possible vulnerability to autistic traits. The prevalence of males with more than one extra sex chromosome (e.g., 48,XXYY and 48,XXXY) and an additional Y (e.g., 47,XYY) is less common, but it is important to understand their social functioning as it provides insight into treatment implications.

Congenital defect of the partial atrioventricular canal with Klinefelter syndrome

The case of a 25-year-old man with a partial atrioventricular canal defect (PAVCD) with Klinefelter syndrome is reported here. The patient had Klinefelter syndrome associated with an atrial septal defect and the cleft of the anterior leaflet of the mitral valve.

Endodontic treatment in three taurodontic teeth associated with 48,XXXY Klinefelter syndrome: a review and case report

Klinefelter syndrome (KS) is the most common chromosomal abnormality in humans. Taurodontism may occur as one of many dentofacial manifestations of KS and can be detected before development of other physical characteristics. Identification of patients with taurodontic teeth may lead to early recognition of the disorder and could substantially improve quality of life. The objective of this report is to review the general characteristics and dentofacial manifestations of KS, specifically taurodontism, and present a patient with the 48,XXXY variant where root-canal therapy was successfully completed in 3 anatomically varied taurodontic teeth.

Behavioral phenotype of sex chromosome aneuploidies: 48,XXYY, 48,XXXY, and 49,XXXXY

Sex chromosomal aneuploidy is the most common disorder of sex chromosomes in humans, with an incidence of 1 in 400 newborns. The addition of more than one extra X and/or Y chromosome to a normal male karyotype is less frequent and has its own distinctive physical and behavioral profile. This study examines the behavioral similarities and differences in individuals with 48,XXYY compared to 48,XXXY and 49,XXXXY. The participants include 11 males with 48,XXYY and 13 males with 48,XXXY and 49,XXXXY. Using the Vineland Adaptive Behavior, the Achenbach Child Behavior Checklist, and the Reiss Personality Profiles, parents are asked to characterize the behavior and personality of their boys with sex chromosome tetrasomy and pentasomy. Males with 48,XXYY have higher overall adaptive scales in daily living skills, socialization, and communication compared to males with 48,XXXY and 49,XXXXY. Both groups are at risk for maladaptive behavior, although 48,XXYY males are at a higher risk for internalizing and externalizing symptoms. 48,XXXY and 49,XXXXY function at a lower cognitive level and their behavior is often immature for their chronological age. Both groups display interests in helping others, but have a low tolerance for being rejected or teased. Specific recommendations and interventional strategies are provided for individuals with 48,XXYY, 48,XXXY, and 49,XXXXY.

Genetic basis for congenital heart defects: current knowledge: a scientific statement from the American Heart Association Congenital Cardiac Defects Committee, Council on Cardiovascular Disease in the Young: endorsed by the American Academy of Pediatrics

The intent of this review is to provide the clinician with a summary of what is currently known about the contribution of genetics to the origin of congenital heart disease. Techniques are discussed to evaluate children with heart disease for genetic alterations. Many of these techniques are now available on a clinical basis. Information on the genetic and clinical evaluation of children with cardiac disease is presented, and several tables have been constructed to aid the clinician in the assessment of children with different types of heart disease. Genetic algorithms for cardiac defects have been constructed and are available in an appendix. It is anticipated that this summary will update a wide range of medical personnel, including pediatric cardiologists and pediatricians, adult cardiologists, internists, obstetricians, nurses, and thoracic surgeons, about the genetic aspects of congenital heart disease and will encourage an interdisciplinary approach to the child and adult with congenital heart disease.

XXY (Klinefelter syndrome): a pediatric quantitative brain magnetic resonance imaging case-control study

OBJECTIVE

An extra X chromosome in males (XXY), known as Klinefelter syndrome, is associated with characteristic physical, cognitive, and behavioral features of variable severity. The objective of this study was to examine possible neuroanatomical substrates of these cognitive and behavioral features during childhood and adolescence.

METHODS

MRI brain scans were acquired for 42 XXY and 87 healthy XY age-matched control males. We compared these 2 groups on regional brain volumes and cortical thickness.

RESULTS

Total cerebral volume and all lobar volumes except parietal white matter were significantly smaller in the XXY group, whereas lateral-ventricle volume was larger. Consistent with the cognitive profile, the cortex was significantly thinner in the XXY group in left inferior frontal, temporal, and superior motor regions.

CONCLUSION

The brain-imaging findings of preferentially affected frontal, temporal, and motor regions and relative sparing of parietal regions are consistent with observed cognitive and behavioral strengths and weaknesses in XXY subjects.

Klinefelter syndrome and other sex chromosomal aneuploidies

The term Klinefelter syndrome (KS) describes a group of chromosomal disorder in which there is at least one extra X chromosome to a normal male karyotype, 46,XY. XXY aneuploidy is the most common disorder of sex chromosomes in humans, with prevalence of one in 500 males. Other sex chromosomal aneuploidies have also been described, although they are much less frequent, with 48,XXYY and 48,XXXY being present in 1 per 17,000 to 1 per 50,000 male births. The incidence of 49,XXXXY is 1 per 85,000 to 100,000 male births. In addition, 46,XX males also exist and it is caused by translocation of Y material including sex determining region (SRY) to the X chromosome during paternal meiosis. Formal cytogenetic analysis is necessary to make a definite diagnosis, and more obvious differences in physical features tend to be associated with increasing numbers of sex chromosomes. If the diagnosis is not made prenatally, 47,XXY males may present with a variety of subtle clinical signs that are age-related. In infancy, males with 47,XXY may have chromosomal evaluations done for hypospadias, small phallus or cryptorchidism, developmental delay. The school-aged child may present with language delay, learning disabilities, or behavioral problems. The older child or adolescent may be discovered during an endocrine evaluation for delayed or incomplete pubertal development with eunuchoid body habitus, gynecomastia, and small testes. Adults are often evaluated for infertility or breast malignancy. Androgen replacement therapy should begin at puberty, around age 12 years, in increasing dosage sufficient to maintain age appropriate serum concentrations of testosterone, estradiol, follicle stimulating hormone (FSH), and luteinizing hormone (LH). The effects on physical and cognitive development increase with the number of extra Xs, and each extra X is associated with an intelligence quotient (IQ) decrease of approximately 15-16 points, with language most affected, particularly expressive language skills.

Two Boys with 47, XXY and Autism

Two children with autism and Klinefelter syndrome (KS) (47, XXY) are presented. Both qualify for the diagnosis of autism based on DSM-IV with severely delayed and disordered language, difficulties with social interaction, and a restricted range of interests and activities. Both also have abnormal EEGs, and one patient has had what appear to be clinical seizures. Trials of antiepileptic medications have not been beneficial in either patient. We report the clinical and EEG findings of each patient, and discuss the implications of this combination of disorders.

Puberty-related influences on brain development

Puberty is a time of striking changes in cognition and behavior. To indirectly assess the effects of puberty-related influences on the underlying neuroanatomy of these behavioral changes we will review and synthesize neuroimaging data from typically developing children and adolescents and from those with anomalous hormone or sex chromosome profiles. The trajectories (size by age) of brain morphometry differ between boys and girls, with girls generally reaching peak gray matter thickness 1-2 years earlier than boys. Both boys and girls with congenital adrenal hyperplasia (characterized by high levels of intrauterine testosterone), have smaller amygdala volume but the brain morphometry of girls with CAH did not otherwise significantly differ from controls. Subjects with XXY have gray matter reductions in the insula, temporal gyri, amygdala, hippocampus, and cingulate-areas consistent with the language-based learning difficulties common in this group.

Early androgen deficiency in infants and young boys with 47,XXY Klinefelter syndrome

BACKGROUND/AIMS

Klinefelter syndrome (KS) is characterized by the karyotype 47,XXY. In this study, we evaluated the physical and testicular failure phenotypes of infants and young boys with KS.

METHODS

The evaluation included auxologic measurements, biologic indices of testicular function, and clinical assessment of muscle tone in 22 infants and young boys with KS, ages 1-23 months.

RESULTS

Mean length, weight, and head circumference in SDS were generally within the normal range at -0.3 +/- 1.0, -0.1 +/- 1.4, and 0.0 +/- 1.5, respectively. Mean penile length and testicular volume SDS were -0.9 +/- 0.8 and -1.1 +/- 0.8, indicating significantly reduced penile and testicular size. Mean testosterone levels for the boys < or =6 and >6-23 months were 128 +/- 131 (4.4 +/- 4.5 nmol/l) and 9.5 +/- 7.2 ng/dl (0.3 +/- 0.2 nmol/l), respectively. High-arched palate was observed in 6/17 boys and clinodactyly (5th finger) was observed in 15/16 boys. Hypotonia was evaluated clinically and was noted to be present in 12/17 boys.

CONCLUSION

The physical phenotype in infants and young boys with KS (1-23 months old) includes normal auxologic measurements and early evidence of testicular failure. Muscle tone was decreased in most of the boys. Testicular volume and penile length were diminished, indicating early androgen deficiency. The neonatal surge in testosterone was attenuated in our KS population. Thus, infants and young boys with KS have evidence of early testicular failure. The etiology of this failure and the clinical role of early androgen replacement require further study.

A patient with Klinefelter's syndrome and thalassemia intermedia

Klinefelter's syndrome (KS) is associated with a wide spectrum of clinical features, such as tall stature, eunuchoid proportions, testes disproportionately small for the level of pubertal development, gynecomastia and behavioral problems. The association of KS with thalassemia intermedia has not been previously reported. A male patient with thalassemia intermedia was diagnosed with KS at the age of 14 years when endocrine evaluation for delayed puberty showed hypergonadotrophic hypogonadism. Thyroid function was normal; however, basal and GnRH-stimulated gonadotropin concentrations were raised while serum testosterone was low. Karyotype analysis revealed KS (47,XXY). Testosterone replacement therapy started soon after diagnosis and now at the age of 20 years the patient's height is 178.3 cm, the U/L ratio is 0.91. Testicular volume is 12 ml (Prader orchidometer) and his pubic hair is stage 4. To our knowledge this is the first case of a patient suffering from KS and thalassemia intermedia reported in the literature.

X-chromosome inactivation patterns and androgen receptor functionality influence phenotype and social characteristics as well as pharmacogenetics of testosterone therapy in Klinefelter patients

Klinefelter syndrome is characterized by a vast range of phenotypes related to androgen effects. Testosterone (T) acts via the X-linked androgen receptor gene carrying the CAG repeat (CAGn) polymorphism, the length of which is inversely associated with androgen action and might account for the marked variation in phenotypes. In 77 newly diagnosed and untreated Klinefelter patients with a 47,XXY karyotype we assessed phenotype and social traits in relation to X-weighted biallelic CAGn length using X-chromosome inactivation analysis after digestion of leukocyte DNA with methylation-sensitive HpaII. Forty-eight men were hypogonadal and received T substitution therapy; in these, pharmacogenetic effects were investigated. The shorter CAGn allele was preferentially inactive. CAGn length was positively associated with body height. Bone density and the relation of arm span to body height were inversely related to CAGn length. The presence of long CAGn was predictive for gynecomastia and smaller testes, whereas short CAGn were associated with a stable partnership and professions requiring higher standards of education also when corrected for family background. There was a trend for men with longer CAGn to be diagnosed earlier in life. Under T substitution, men with shorter CAGn exhibited a more profound suppression of LH levels, augmented prostate growth, and higher hemoglobin concentrations. A significant genotype-phenotype association exists in Klinefelter patients: androgen effects on appearance and social characteristics are modulated by the androgen receptor CAGn polymorphism. The effects of T substitution are pharmacogenetically modified. This finding is magnified by preferential inactivation of the more functional short CAGn allele.

Klinefelter's syndrome

Klinefelter's syndrome is the most common genetic cause of human male infertility, but many cases remain undiagnosed because of substantial variation in clinical presentation and insufficient professional awareness of the syndrome itself. Early recognition and hormonal treatment of the disorder can substantially improve quality of life and prevent serious consequences. Testosterone replacement corrects symptoms of androgen deficiency but has no positive effect on infertility. However, nowadays patients with Klinefelter's syndrome, including the non-mosaic type, need no longer be considered irrevocably infertile, because intracytoplasmic sperm injection offers an opportunity for procreation even when there are no spermatozoa in the ejaculate. In a substantial number of azoospermic patients, spermatozoa can be extracted from testicular biopsy samples, and pregnancies and livebirths have been achieved. The frequency of sex chromosomal hyperploidy and autosomal aneuploidies is higher in spermatozoa from patients with Klinefelter's syndrome than in those from normal men. Thus, chromosomal errors might in some cases be transmitted to the offspring of men with this syndrome. The genetic implications of the fertilisation procedures, including pretransfer or prenatal genetic assessment, must be explained to patients and their partners.

Colobomas of the iris and choroid and high signal intensity cerebral foci on T2-weighted magnetic resonance images in Klinefelter's syndrome

A 5-year-old boy presented with ocular anomalies including microphthalmos, colobomas of the iris, choroid, and optic nerve head, and strabismus. Magnetic resonance imaging of the head showed multiple bilateral asymmetric high signal intensity foci in the subcortical and periventricular white matter. Genetic counseling disclosed a 47,XXY karyotype.

De novo germinoma in the brain in association with Klinefelter's syndrome: case report and review of the literature

BACKGROUND

There are no previous reports about de novo germ cell tumors without any past history of germ cell tumor. We describe a case of de novo cerebral germinoma in association with Klinefelter's syndrome.

CASE DESCRIPTION

A boy had undergone growth hormone therapy for dwarfism because of hypopituitarism from 10 to 17 years old. The result of karyotyping at the age of 13 was 47,XXY. Magnetic resonance images (MRI) of the brain at the age of 17 years showed no lesions. Two years later, at the age of 19, the patient noticed onset of mild right hemiparesis. MR imaging revealed the existence of a brain tumor in the left temporal lobe and hypothalamus. The patient underwent an operation and the histologic diagnosis of the lesion was germinoma. After postoperative chemotherapy and radiation therapy, the lesion disappeared and the patient was discharged uneventfully.

CONCLUSIONS

To the best of the authors' knowledge, this is the first reported case of a germ cell tumor to be de novo without any past history of other germ cell tumor and the seventh case in which it occurred in association with Klinefelter's syndrome.

Klinefelter syndrome: Expanding the phenotype and identifying new research directions

PURPOSE

The purpose of this study is to summarize new data on etiology and clinical features of Klinefelter syndrome in order to derive research priorities.

METHODS

This study was conducted using critical reviews of selective topics, emphasizing less well-recognized clinical findings.

RESULTS AND CONCLUSIONS

The phenotype of the prototypic 47,XXY case is well recognized: seminiferous tubule dysgenesis and androgen deficiency. Less well appreciated is the varied expressivity of 47,XXY Klinefelter syndrome, in particular neurological/cognitive perturbations like language and behavioral problems. Effective therapies are available. Reproductive technologies allow 47,XXY men to sire offspring through intracytoplasmic sperm injection (ICSI); however, genetic counseling is complex and success is low. Behavioral and expressive language difficulties are amenable to treatment by androgen therapy and psychological help. Early treatment may be imperative for optimal outcome.