Onset and progression of puberty in Klinefelter syndrome

Klinefelter Syndrome: A Review

BACKGROUND

Klinefelter syndrome (KS) is an uncommonly recognised condition typified by gynaecomastia, small testes and aspermatogenesis. It is caused by a supernumerary X chromosome, resulting in a 47 XXY karyotype. Since its first description, the phenotype of KS has evolved and there is a much greater appreciation of the subtle features of the condition.

METHOD

In this review, we explore the phenotype of the KS with particular consideration to patients with pre-natal and early infancy diagnosis, given that this is becoming increasingly common. The current understanding of the genetic mechanisms of KS, caused by supernumerary X chromosome are explored and the genotype-phenotype correlation are discussed.

RESULTS

The implications of the condition both in childhood and later development are explored in detail, with particular focus on social and educational implications. Potential treatments, with emphasis on preservation of fertility are discussed. We highlight the optimal therapeutic conditions in which fertility preservation is most likely to be achieved, compared to those which can be more challenging. Finally, we discuss the other health challenges which can be associated with KS. These include poor bone health, diabetes, cardiovascular complications, and malignancy. The challenges in managing these co-morbid conditions and most up-to-date management recommendations are also explored.

Effect of testosterone treatment during puberty in boys with Klinefelter syndrome (The TIPY Study): protocol for a nationwide randomised, double-blinded, placebo-controlled study

INTRODUCTION

Klinefelter syndrome (KS) is a genetic condition characterised by the presence of an extra X chromosome in males (47,XXY). KS is associated with various phenotypic characteristics in adult life, including infertility, hypogonadism and increased risk of type II diabetes, cardiovascular disease and osteoporosis. Additionally, individuals with KS often experience mental health challenges and functional impairments that significantly impact their quality of life. Currently, testosterone replacement therapy (TRT) in adolescence is considered the first-line treatment by some physicians for patients with KS and biochemical signs of hypogonadism. However, comprehensive evidence on its effectiveness in preventing typical phenotypic traits associated with KS remains limited, and, currently, no evidence-based recommendations for TRT in this population exist. We therefore aim to evaluate the effects of two years of TRT during puberty in boys with KS. The primary endpoint is to monitor changes in body fat percentage. Secondary endpoints include changes in pubertal development and virilisation, growth and body proportions, bone mineralisation, muscle strength, lipid and glucose metabolism, systemic inflammation, methylation, fertility and effects on the cognitive and psychopathological features of KS.

METHODS AND ANALYSIS

The TIPY study is a multicentre, national, randomised, double-blind, placebo-controlled intervention study. Participants will be recruited from four tertiary paediatric endocrine units in Denmark that manage boys with KS. Participants will be randomised to treatment with transdermal placebo or transdermal testosterone (Androgel; Besins Healthcare, Paris, France) with dose titration every 3 months based on individual measurements of serum concentrations of testosterone. Dose titration will be conducted by a single physician to ensure free testosterone remains between +1 and +3 SD for age.Thorough clinical and biochemical evaluation will be performed at baseline, after 12 months and 24 months. Additional visits for minor evaluations will occur every 3 months. Neuropsychological assessment will be conducted at baseline and after 24 months of treatment.

ETHICS AND DISSEMINATION

The study will be conducted in accordance with the Helsinki Declaration. The study has been approved by the Danish National Medical Research Ethics Committee and the Danish Medicines Agency (Clinical trials information system number 2023-505854-16-00). Results will be submitted for publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT06294990.

Social, Emotional, and Behavioral Functioning in Adolescents With Klinefelter Syndrome

OBJECTIVE

Klinefelter syndrome (KS) is a common genetic condition in males associated with an extra X chromosome (i.e., 47,XXY). Individuals with KS often experience androgen insufficiency and tall stature and are at increased risk for depression, anxiety, and social challenges. This cross-sectional study investigates social and emotional functions in 52 boys with KS and 62 typically developing (TD) boys, aged 8 to 13 years.

METHODS

Self-report measures of anxiety, depression, and behavior and parent-report measures of social functioning and behavior were completed. In primary analyses, linear regression was used to test the effect of group (KS, TD) on standardized scores derived from widely used rating scales. In secondary analyses, we explored the influence of pubertal status on these scores and concordance between self- and parent ratings.

RESULTS

Our results indicate that boys with KS exhibit significantly increased anxiety, depression, and social difficulties relative to TD peers. Among participants with KS, peripubertal boys generally experienced more difficulties in aspects of social and emotional functioning as compared to prepubertal boys. Concordance analyses revealed differences between parent- and child-reports.

CONCLUSION

These findings indicate that alterations in social, emotional, and behavioral functions are present in boys and adolescents with KS and may be influenced by puberty.

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.

Utility of evaluating semen samples from adolescents with Klinefelter Syndrome for cryopreservation: A multi-institution evaluation

INTRODUCTION

Klinefelter Syndrome (KS) is the most common genetic condition cause of non-obstructive azoospermia (NOA). KS also often results in decreased testicular growth and testosterone production. Because of this, exogenous testosterone therapy is commonly prescribed for KS patients to treat hypogonadism, but this may have additional impacts to future fertility potential. KS adolescent patients may be asked to provide multiple semen samples to identify potential sperm for early cryopreservation.

OBJECTIVE

To develop a multi-institutional database to evaluate the prevalence of sperm in the ejaculate of adolescent KS patients.

METHODS

A retrospective study was performed of all adolescent KS patients seen at two high-volume tertiary male infertility clinics between 2015 and 2020. Adolescence was defined as individuals aged 12-19 years, as per the World Health Organization. Demographic information data including weight, height, medical comorbidities, and concurrent medications were collected. Serum hormone levels including FSH, LH, and testosterone were collected, as well as any available semen analysis data.

RESULTS

A total of 116 patients were identified and included in the database. A total of 100 (86.2%) had hormone data available and 48 (41.3%) had semen analysis data. Of the 48 patients with semen analyses, only 4 (8.3%) patients had rare sperm in the ejaculate while the remaining had azoospermia (91.7%). None of the specimens were suitable for cryopreservation. The average serum total testosterone level of adolescent KS patients was 181 ± 216 ng/dL. FSH levels were 14.3 ± 18.8 IU/L (normal 0.3-10.0 IU/L) and LH levels were 7.8 ± 12.4 IU/L (normal 1.2-7.8 IU/L). A total of 17 patients repeated a semen analysis, and in no instance did this result in sperm where there was none previously.

CONCLUSION

The findings from a large multicenter retrospective cohort of adolescent KS patients suggest that a single semen analysis is sufficient for attempted cryopreservation purposes, and that multiple semen analyses is not needed.

Delayed puberty in boys in central Sweden: an observational study on diagnosing and management in clinical practice

OBJECTIVES

To compare the usefulness of the classical definition of delayed puberty (DP) in boys with puberty nomograms and to describe the management of DP in boys in a hospital-based setting.

STUDY DESIGN

Observational retrospective multicentre study with a short-term follow-up.

SETTING AND PARTICIPANTS

Boys diagnosed with DP during 2013-2015 at paediatric departments in four counties in central Sweden. The medical records of 165 boys were reviewed.

PRIMARY AND SECONDARY OUTCOME MEASURES

Number of boys with DP after re-evaluation of the diagnosis according to the classical definition in comparison with puberty nomograms. Description of investigations performed and treatment provided to boys with DP.

RESULTS

In total, 45 and 58 boys were found to have DP according to the classical definition and the nomograms, respectively. Biochemical and/or radiological testing was performed in 91% of the 58 boys, but an underlying disease was only found in 9% of them. Approximately 79% of the boys received testosterone treatment, either as injections of testosterone enanthate or as testosterone undecanoate.

CONCLUSIONS

Puberty nomograms may be helpful instruments when diagnosing pubertal disorders in boys as they are not limited to an age close to 14 years and also identify boys with pubertal arrest. The majority of boys with DP undergo biochemical or radiological examinations, but underlying diseases are unusual emphasising the need for structural clinical practice guidelines for this patient group.