Klinefelter Syndrome in Childhood: Variability in Clinical and Molecular Findings

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.

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.

What Every Internist-Endocrinologist Should Know about Rare Genetic Syndromes in Order to Prevent Needless Diagnostics, Missed Diagnoses and Medical Complications: Five Years of 'Internal Medicine for Rare Genetic Syndromes'

Patients with complex rare genetic syndromes (CRGS) have combined medical problems affecting multiple organ systems. Pediatric multidisciplinary (MD) care has improved life expectancy, however, transfer to internal medicine is hindered by the lack of adequate MD care for adults. We have launched an MD outpatient clinic providing syndrome-specific care for adults with CRGS, which, to our knowledge, is the first one worldwide in the field of internal medicine. Between 2015 and 2020, we have treated 720 adults with over 60 syndromes. Eighty-nine percent of the syndromes were associated with endocrine problems. We describe case series of missed diagnoses and patients who had undergone extensive diagnostic testing for symptoms that could actually be explained by their syndrome. Based on our experiences and review of the literature, we provide an algorithm for the clinical approach of health problems in CRGS adults. We conclude that missed diagnoses and needless invasive tests seem common in CRGS adults. Due to the increased life expectancy, an increasing number of patients with CRGS will transfer to adult endocrinology. Internist-endocrinologists (in training) should be aware of their special needs and medical pitfalls of CRGS will help prevent the burden of unnecessary diagnostics and under- and overtreatment.

Massive Pulmonary Emboli in Klinefelter Syndrome: A Rare Case Report

Introduction

Klinefelter syndrome (KS) is a genetic disorder that affects men. An augmented incidence of the thromboembolic event described in patients with KS.

Case Presentation

A 34-year-old male identified with a definitive diagnosis of KS was hospitalized to our cardiac surgery center through the emergency with chief complaints of acute chest pain and dyspnea. Saddle pulmonary thromboembolism was established from chest Computed Tomography Angiography (CTA). The patient's symptoms resolved after embolectomy via surgery.

Conclusions

There is a tendency for hypercoagulability in KS. This tendency is because of hormonal discrepancy and hereditary thrombophilic factors. So, patients with KS and past medical history of venous thromboembolism necessitate constant oral anticoagulation therapy.

Androgenization in Klinefelter syndrome: Clinical spectrum from infancy through young adulthood

Klinefelter syndrome (KS) is an uncommon chromosomal disorder in males that has a variable clinical appearance. Classic KS involves an extra X chromosome, (47, XXY), although other variations may exist, including a milder mosaic form as well as multiple extra sex chromosomes with more dramatic phenotypes. KS is underdiagnosed, especially pre-pubertally, owing to a paucity of concrete clinical signs; however, diagnostic rates increase during and after puberty, as the consequences of hypergonadotropic hypogonadism begin to manifest. Testicular failure causing decreased circulating testosterone (T) and germ cell depletion, a hallmark feature in KS, commonly begins shortly after the onset of puberty and leads to the most commonly recognized KS traits: small testes, azoospermia, gynecomastia, decreased facial and pubic hair. While many KS men maintain adequate T levels leading up to young adulthood, some may have lower T levels at an earlier age leading to varied levels of androgenization and clinical KS features. At certain critical time points, absent or decreased T may alter the development of normal male reproductive organs, external genitalia, development of secondary sexual characteristics and spermatogenesis. Testicular failure in utero may lead to ambiguous genitalia, cryptorchidism and/or hypospadias, all of which depend on fetal T production. In the neonatal period and childhood, decreased T levels during the mini-puberty of infancy may negatively impact germ cell differentiation and male neuropsychological development. Finally, decreased T during pubertal and young adulthood can lead to decreased virilization during puberty, eunuchoid skeleton and decreased spermatogenesis. Depending on the timing of the testicular failure, a reproductive window of sperm production may exist to achieve paternity for KS men. The presence or absence of clinical characteristics reflecting decreased androgenization provides an insight to the relative testicular function during these developmental time points for those with KS and contributes to variability within the syndrome.

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.

MRI findings of nonobstructive azoospermia: lesions in and out of pelvic cavity

Nonobstructive azoospermia (NOA) can be caused by various diseases, including congenital disorders, endocrine disorders, infections, tumor or tumor-like diseases, vascular diseases, etc. Diagnosis of the underlying cause of NOA is complicated and challenging. In this study, we introduce an MR examination protocol for the etiological diagnosis of NOA, and demonstrate a series of NOA patients with different causes and imaging findings. Except for lesions of testes, the patients may also combine abnormalities of adrenal glands and central nervous system. In such cases, the patients could benefit from additional abdominal and intracranial scans.

Klinefelter Syndrome: Clinical Spectrum Based on 44 Consecutive Cases from a South Indian Tertiary Care Center

BACKGROUND

Klinefelter syndrome (KFS) is the commonest chromosomal abnormality, yet remains largely underdiagnosed due to its varied clinical presentation. This study was done to understand the clinical spectrum in our population.

AIM

We intended to study the clinical characteristics of children and adults with KFS in our population. We also desired to identify any special features of Klinefelter variants.

METHODS

Forty-four patients with karyotype diagnosis of KFS during the time period 2007-2015 were included in this retrospective study. Clinical details and hormonal profile were obtained from hospital information system.

RESULTS

Our study population consisted of 17 (38.6%) participants in pediatric age group (age <18 years) and 27 (61.4%) adults. Clinical presentation prompting evaluation in the former group included cardiac anomalies (29.4%), dysmorphism (23.5%), hypogonadism (17.6%), developmental delay (11.8%), tall stature (11.8%), and cryptorchidism (5.9%). Among adults, 16 (59.2%) presented with hypogonadism and 9 (20.4%) had primary infertility. Six children (35.3%) had micropenis and four (three children, one adult) had unilateral undescended testis. Behavioral problems were detected in 19 (43.2%) subjects. Mean follicle stimulating hormone (FSH) and luteinizing hormone (LH) values were 38 IU/mL and 18 IU/mL, respectively. The classical 47 XXY karyotype was detected in 38 (86.4%) subjects and 6 (13.6%) had karyotype consistent with Klinefelter variants.

CONCLUSION

KFS was diagnosed only after 18 years of age in two-thirds of patients. Developmental delay, cardiac anomalies, behavioral abnormalities, and intellectual disabilities were the common presentations in pediatric subjects. Adults predominantly presented with hypogonadism. Individuals with Klinefelter variant karyotype sought medical attention predominantly for non-gonadal concerns.

Endocrine aspects of Klinefelter syndrome

PURPOSE OF REVIEW

Klinefelter syndrome is the most common sex chromosome abnormality in men. Hypogonadism and testicular degeneration are almost universal. Truncal adiposity, metabolic syndrome and low bone mass occur frequently. This review summarizes the most recent advances in the pathogenesis and management of the endocrine abnormalities in Klinefelter syndrome. It is expected that optimal endocrine management will improve outcomes and quality of life in Klinefelter syndrome.

RECENT FINDINGS

In Klinefelter syndrome, testosterone replacement is routinely prescribed despite lack of evidence on the optimal dose and time for initiation of therapy. Cross-sectional studies have linked hypogonadism to the development of metabolic abnormalities and low bone mass. Testosterone therapy, however, is not consistently associated with improved metabolic and bone outcomes. Increased truncal adiposity and high rates of metabolic syndrome are present in prepubertal children. A randomized trial of oxandrolone in prepubertal boys showed improvement in visual-motor function, socialization and cardiometabolic health. Testicular sperm extraction (TESE) has success rates similar to other causes of nonobstructive azoospermia when performed between 16 and 35 years of age.

SUMMARY

Endocrine care in Klinefelter syndrome should start in childhood and include evaluation of metabolic risk factors and bone health. Further research to guide evidence-based endocrine care is very much needed.

Recent advances in managing and understanding Klinefelter syndrome

Klinefelter syndrome can present as a wide spectrum of clinical manifestations at various stages in life, making it a chromosomal disorder with no standardized set of guidelines for appropriate management. Understanding the genetic and hormonal causes of this syndrome can allow physicians to treat each patient on a more individualized basis. The timing of diagnosis and degree of symptoms can guide management. This report will provide an updated review of the clinical presentation at various stages in life and the implications for management.