Thyroid function in Klinefelter syndrome: a multicentre study from KING group

Klinefelter Syndrome: A Genetic Disorder Leading to Neuroendocrine Modifications and Psychopathological Vulnerabilities in Children-A Literature Review and Case Report

Klinefelter syndrome (KS), characterized by an additional X-chromosome in males, manifests in a wide range of neuroendocrine and psychiatric symptoms. Individuals with KS often face increased risks of hormonal dysfunction, leading to depression and anxiety, although extended research during pediatric and adolescent age is still limited. This critical phase, decisive for KS children, is influenced by a combination of genetic, environmental and familial factors, which impact brain plasticity. In this report, we reviewed, in a narrative form, the crucial KS psychopathological hallmarks in children. To better describe neuroendocrine and neuropsychiatric outcomes in children with KS, we presented the case of an 11-year-old prepubertal child with mosaic KS who was referred to our Center of Developmental Psychopathology due to a decline in his academic performance, excessive daytime fatigue and increased distractibility over the past few months. Family history revealed psychiatric conditions among first- and second-degree relatives, including recently divorced parents and a 15-year-old sister. Early-onset persistent depressive disorder and anxious traits were diagnosed. Timely identification of susceptible children, with thorough examination of familial psychiatric history, environmental influences and neurocognitive profile, alongside targeted interventions, could potentially mitigate lifelong psychopathology-related disabilities in pediatric and adolescent KS cases, including those with mosaic KS.

Altered Thyroid Feedback Loop in Klinefelter Syndrome: From Infancy Through the Transition to Adulthood

CONTEXT

It has been claimed that thyroid dysfunction contributes to the spectrum of Klinefelter syndrome (KS); however, studies are scarce.

OBJECTIVE

In a retrospective longitudinal study, we aimed at describing the hypothalamic-pituitary-thyroid (HPT) axis and thyroid ultrasonographic (US) appearance in patients with KS throughout the life span.

METHODS

A total of 254 patients with KS (25.9 ± 16.1 years) were classified according to their pubertal and gonadal status and compared with different groups of non-KS age-matched individuals with normal thyroid function, treated and untreated hypogonadism, or chronic lymphocytic thyroiditis. We assessed serum thyroid hormone levels, antithyroid antibodies, US thyroid parameters, and in vitro pituitary type 2 deiodinase (D2) expression and activity.

RESULTS

Thyroid autoimmunity was more prevalent among individuals with KS at all ages, although the antibody (Ab)-negative vs Ab-positive cohorts were not different. Signs of thyroid dysfunction (reduced volume, lower echogenicity, and increased inhomogeneity) were more prominent in KS than in euthyroid controls. Free thyroid hormones were lower in prepubertal, pubertal, and adult patients with KS, whereas thyrotropin values were lower only in adults. Peripheral sensitivity to thyroid hormones was unaltered in KS, suggesting a dysfunctional HPT axis. Testosterone (T) was the only factor associated with thyroid function and appearance. In vitro testing demonstrated an inhibitory effect of T on pituitary D2 expression and activity, supporting enhanced central sensing of circulating thyroid hormones in hypogonadism.

CONCLUSION

From infancy through adulthood, KS is characterized by increased morphofunctional abnormalities of the thyroid gland, combined with a central feedback dysregulation sustained by the effect of hypogonadism on D2 deiodinase.

Increased prevalence of nodular thyroid disease in patients with Klinefelter syndrome

PURPOSE

Thyroid dysfunction in patients with Klinefelter syndrome (KS) remains an unresolved issue. Although low free thyroxine (FT4) levels within the normal range and normal thyroid stimulating hormone (TSH) levels have been reported, there is currently no data on nodular thyroid disease in this population. This study aims to evaluate the results of thyroid ultrasound (US) examinations in KS patients compared with healthy controls.

METHODS

A cohort of 122 KS and 85 age-matched healthy male controls underwent thyroid US screening and thyroid hormone analysis. According to US risk-stratification systems, nodules ≥1 cm were examined by fine needle aspiration (FNA).

RESULTS

Thyroid US detected nodular thyroid disease in 31% of KS compared to 13% of controls. No statistical differences in the maximum diameter of the largest nodules and in moderate and highly suspicious nodules were found between patients and the control group. Six KS patients and two controls with nodules underwent FNA and were confirmed as cytologically benign. In line with published data, FT4 levels were found significantly near the lower limit of the normal range compared to controls, with no differences in TSH values between the two groups. Hashimoto's thyroiditis was diagnosed in 9% of patients with KS.

CONCLUSIONS

We observed a significantly higher prevalence of nodular thyroid disease in KS compared to the control group. The increase in nodular thyroid disease is likely linked to low levels of FT4, inappropriate TSH secretion, and/or genetic instability.

First baseline data of the Klinefelter ItaliaN Group (KING) cohort: clinical features of adult with Klinefelter syndrome in Italy

BACKGROUND

Klinefelter syndrome (KS) is frustratingly under-diagnosed. KS have a broad spectrum of clinical features, making it difficult to identify.  OBJECTIVE: We describe KS clinical presentation in a large Italian cohort.

DESIGN

This is the first observational cohort study within a national network, the Klinefelter ItaliaN Group (KING). Primary outcomes were to describe the basic clinical features and the actual phenotype of KS in Italy. Secondary outcomes were to determine age at diagnosis and geographical distribution.

METHODS

We performed a basic phenotyping and evaluation of the hormonal values of 609 adult KS patients.

RESULTS

Mean age at diagnosis was 37.4 ± 13.4 years. The overall mean testicular size was 3 ml, and 2.5 ml in both testes in untreated KS group. BMI was 26.6 ± 5.8 kg/m², and 25.5% of KS had metabolic syndrome (MetS). LH and FSH were increased, and mean total testosterone were 350 ± 9.1 ng/dl. A descriptive analysis showed that 329 KS patients were evaluated in Northern Italy, 76 in Central and 204 in Southern Italy. Analysis of variance demonstrated significant statistical differences (p < 0001) between the age at diagnosis of the three geographical groups. Compared with the expected number among male patients matched for age in Italy, only 16% of KS patients received a diagnosis.

CONCLUSIONS

These data are the results of the only national database available that collects the clinical and hormonal data of the KS patients, currently referred at the KING centers. In Italy the typical KS patient is overweight, with small testes, and elevated LH and FSH. Only 25.5% of them are diagnosed with MetS. Early detection and timely treatment are mandatory.

Erectile Dysfunction and Decreased Libido in Klinefelter Syndrome: A Prevalence Meta-Analysis and Meta-Regression Study

BACKGROUND

Only few studies have assessed sexual dysfunction in men with Klinefelter syndrome (KS).

AIM

To define pooled prevalence estimates and correlates of erectile dysfunction (ED) and decreased libido (DL) in KS.

METHODS

A thorough search of Medline, Embase and Web of Science was performed to identify suitable studies. Quality of the articles was scored using the Assessment Tool for Prevalence Studies. Data were combined using random effect models and the between-studies heterogeneity was assessed by the Cochrane's Q and I². The sources of heterogeneity were investigated by meta-regression and sub-group analyses. Funnel plot, Begg's rank correlation and trim-and-fill test were used to assess publication bias.

MAIN OUTCOME MEASURE

The pooled prevalence of ED and DL in KS as well as 95% confidence intervals (CIs) were estimated from the proportion of cases of sexual dysfunction and the sample size. Variables that could affect the estimates were identified by linear meta-regression models.

RESULTS

Sixteen studies included collectively gave information about ED and DL in 482 and 368 KS men, respectively, resulting in a pooled prevalence of 28% (95% CI: 19%-36%) for ED and 51% (95% CI: 36%-66%) for DL, with a large heterogeneity. The trim-and-fill adjustment for publication bias produced a negligible effect on the pooled estimates. At the meta-regression analyses, a higher prevalence of ED was significantly associated with an older age but not with lower testosterone levels. In series with a mean age >35 years, the ED prevalence estimate increased up to 38% (95% CI: 31%-44%) with no heterogeneity (I²=0.0%, P=0.6). On the contrary, the prevalence of DL increased significantly as testosterone levels decreased, without a significant relationship with age.

CLINICAL IMPLICATIONS

While DL would largely reflect an androgen deficiency, in older men with KS, erectile function should be assessed irrespective of testosterone levels.

STRENGTH & LIMITATIONS

This is the first meta-analysis defining pooled prevalence estimates and correlates of ED and DL in KS. Nevertheless, caution is required when interpreting results, due to the high risk of bias in many studies, as well as the dearth of data about psychosocial and/or psychosexological variables and age at the diagnosis.

CONCLUSIONS

ED and DL represent common clinical complaints in KS. While the prevalence of ED would increase with age, DL gets more common as serum testosterone decreases. Further studies are warranted to elucidate the pathogenetic mechanism(s) underlying the age-dependent increase in the prevalence of ED, apparently unrelated to the androgenic status. A Barbonetti, S D'Andrea, W Vena, et al. Erectile Dysfunction and Decreased Libido in Klinefelter Syndrome: A Prevalence Meta-Analysis and Meta-Regression Study. J Sex Med 2021;18:1054-1064.

Central hypogonadism in Klinefelter syndrome: report of two cases and review of the literature

PURPOSE

Klinefelter syndrome (KS) is characterized by late adolescence/young adulthood onset of primary hypogonadism. Hypogonadotropic hypogonadism (HH), when congenital, is usually associated with absent/incomplete puberty and low/normal gonadotropins. We report the clinical and genetic features of two subjects with KS and an unexpected HH hormone profile.

METHODS

Magnetic resonance imaging (MRI) of hypothalamus-pituitary region and next generation sequencing (NGS) of congenital HH-associated genes were obtained. A narrative review of the literature was conducted.

RESULTS

Patients were diagnosed with Klinefelter syndrome following karyotype analysis. Nevertheless, they showed unusual features: both had incomplete puberty, low gonadotropins and testosterone levels, and the first one was anosmic. Sellar lesions were excluded by MRI, and NGS was negative in both subjects. Our data add to those of the only 14 similar cases reported so far. Unexplained HH rarely occurs in KS and is variably associated with anosmia, other pituitary hormones deficiencies and heterogeneous karyotypes. However, most cases show an early, pre-pubertal onset of hypogonadism. If the causes behind this gonadotropins defect are largely unknown, hereby we provide the first review of the literature on this topic and propose some pathogenetic hypotheses, including the coexistence of KS and congenital HH as suggested by overlapping clinical features in some of these patients.

CONCLUSION

HH is an exceptional occurrence in Klinefelter syndrome and is associated with heterogeneous phenotypes and, probably, aetiologies. Moreover, KS could underlie HH nonresponsive to gonadotropins. An exhaustive diagnostic workup and a tailored clinical management are advisable in these rare forms.

Hashimoto's Thyroiditis and Graves' Disease in Genetic Syndromes in Pediatric Age

Autoimmune thyroid diseases (AITDs), including Hashimoto’s thyroiditis (HT) and Graves’ disease (GD), are the most common cause of acquired thyroid disorder during childhood and adolescence. Our purpose was to assess the main features of AITDs when they occur in association with genetic syndromes. We conducted a systematic review of the literature, covering the last 20 years, through MEDLINE via PubMed and EMBASE databases, in order to identify studies focused on the relation between AITDs and genetic syndromes in children and adolescents. From the 1654 references initially identified, 90 articles were selected for our final evaluation. Turner syndrome, Down syndrome, Klinefelter syndrome, neurofibromatosis type 1, Noonan syndrome, 22q11.2 deletion syndrome, Prader–Willi syndrome, Williams syndrome and 18q deletion syndrome were evaluated. Our analysis confirmed that AITDs show peculiar phenotypic patterns when they occur in association with some genetic disorders, especially chromosomopathies. To improve clinical practice and healthcare in children and adolescents with genetic syndromes, an accurate screening and monitoring of thyroid function and autoimmunity should be performed. Furthermore, maintaining adequate thyroid hormone levels is important to avoid aggravating growth and cognitive deficits that are not infrequently present in the syndromes analyzed.

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.

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.

The Human Microbiota in Endocrinology: Implications for Pathophysiology, Treatment, and Prognosis in Thyroid Diseases

The human microbiota is an integral component in the maintenance of health and of the immune system. Microbiome-wide association studies have found numerous diseases associated to dysbiosis. Studies are needed to move beyond correlations and begin to address causation. Autoimmune thyroid diseases (ATD) are one of the most common organ-specific autoimmune disorders with an increasing prevalence, higher than 5% worldwide. Most frequent manifestations of ATD are Hashimoto's thyroiditis and Graves' disease. The exact etiology of ATD remains unknown. Until now it is not clear whether bacterial infections can trigger ATD or modulate the efficacy of treatment and prognosis. The aim of our review is to characterize the microbiota and in ATD and to evaluate the impact of dysbiosis on treatment and prognosis. Moreover, variation of gut microbiome has been associated with thyroid cancer and benign nodules. Here we will characterize the microbioma in benign thyroid nodules, and papillary thyroid cancer to evaluate their implications in the pathophysiology and progression.

Autoimmune Thyroid Disease in Specific Genetic Syndromes in Childhood and Adolescence

Autoimmune thyroid disease (ATD) is the most frequent cause of acquired thyroid dysfunction, most commonly presenting either as Hashimoto's thyroiditis or Graves' Disease. Hashimoto's thyroiditis is characterized by the presence of thyroid-specific autoantibodies, more commonly anti-thyroperoxidase antibodies in the serum and the typical inhomogeneous echostructure of the thyroid on a thyroid ultrasound examination. Hashimoto's thyroiditis can for a long time be accompanied by normal thyroid function and hypothyroidism can only progressively be established. Graves' disease is much less frequent in childhood and adolescence and presents with overt hyperthyroidism. After the onset of puberty, ATD affects females with a higher incidence than males, while during the prepubertal period there is not such a clear preponderance of affected females. ATD can occur either isolated or in the context of other autoimmune disorders, such as type 1 Diabetes mellitus (T1D), celiac disease, alopecia areata, vitiligo, etc. Especially at the pediatric age, a higher incidence of ATD is also observed in the context of specific genetic syndromes, such as trisomy 21 (Down syndrome), Klinefelter syndrome, Turner syndrome, or 22q11.2 deletion syndrome. Nevertheless, although thyroid dysfunction may also be observed in other genetic syndromes, such as Prader-Willi or Williams syndrome, the thyroid dysfunction in these syndromes is not the result of thyroid autoimmunity. Interestingly, there is emerging evidence supporting a possible link between autoimmunity and RASopathies. In this review article the incidence, as well as the clinical manifestation and accompanied pathologies of ATD in specific genetic syndromes will be presented and regular follow-up for the early identification of the disorder will be proposed.