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

Cardiorespiratory fitness in adolescents and young adults with Klinefelter syndrome - a pilot study

BACKGROUND

Klinefelter syndrome (KS) may be associated with a wide spectrum of phenotypic changes including endocrine, metabolic, cognitive, psychiatric and cardiorespiratory pathologies in adults. However, in adolescence the clinical phenotype of KS is not well described, especially regarding physical fitness. The present study reports on cardiorespiratory function in adolescents and young adults with KS.

METHODS

Adolescents and young adults with KS were recruited in a cross-sectional pilot study. Biochemical parameters of fitness including hormonal status, a body impedance analysis, the grip strength, the amount of physical activity at home for 5 days via trackbands and anamnestic parameters were assessed. In addition, participants underwent an incremental symptom-limited cardiopulmonary exercise test (CPET) on a bicycle ergometer.

RESULTS

Nineteen participants with KS aged 15.90 ± 4.12 years (range: 9.00 - 25.00) participated in the study. Pubertal status was Tanner 1 (n = 2), Tanner 2 - 4 (n = 7) and Tanner 5 (n = 10). Seven participants received testosterone replacement therapy. Mean BMI z-score was 0.45 ± 1.36 and mean fat mass was 22.93% ± 9.09. Grip strength was age-appropriate or above normal. 18 participants underwent CPET with subnormal results for maximum heart rate (z-score -2.84 ± 2.04); maximum workload (Watt_max; z score -1.28 ± 1.15) and maximum oxygen uptake per minute (z- score -2.25 ± 2.46). Eight participants (42.1%) met the criteria for chronotropic insufficiency (CI). Data from track-bands showed sedentary behavior for 81.15% ± 6.72 of the wear time.

CONCLUSION

A substantial impairment of cardiopulmonary function can be detected in this group of boys to young adults with KS, including chronotropic insufficiency in 40%. The track-band data suggest a predominantly sedentary lifestyle, despite normal muscular strength as assessed via grip strength. Future studies need to investigate the cardiorespiratory system and its adaption to physical stress in a larger cohort and in more detail. It is feasible that the observed impairments contribute to the avoidance of sports in individuals with KS and may contribute to the development of obesity and the unfavorable metabolic phenotype.

A dual-center study of predictive factors for sperm retrieval through microdissection testicular sperm extraction and intracytoplasmic sperm injection outcomes in men with non-mosaic Klinefelter syndrome

PURPOSE

This study evaluated the predictors of sperm retrieval (SR) in non-mosaic Klinefelter syndrome (KS) patients undergoing microsurgical testicular sperm extraction (mTESE). The cutoff values of the predictors of SR and overall pregnancy rates after intracytoplasmic sperm injection (ICSI) were analyzed for the positive SR (PSR) cases.

MATERIALS AND METHODS

The study was a dual-center retrospective study. Overall 118 patients with KS underwent mTESE between January 2011 and July 2021. Clinicopathological factors including comorbidities, endocrine profiles, and testicular volumes were analyzed.

RESULTS

A total of 58 patients showed PSR (49.2%) and 60 patients (50.8%) had negative SR (NSR). The mean overall age of the patients was 32.5 years. The NSR patients had a significantly greater prevalence of obesity, diabetes mellitus, and cerebrovascular disease. The PSR group had a significantly higher left testis mean volume (p=0.039). The differences between the two study groups regarding follicular-stimulating hormone, luteinizing hormone, and testosterone variations at 1 and 3 months after mTESE were insignificant. Preoperative mean neutrophil-to-lymphocyte ratio was significantly greater in the NSR group (p=0.011), but the platelet-to-lymphocyte ratio showed no significant difference between the two study groups. A live child birth was achieved in 53.4% of the PSR patients. Multivariate logistic analysis showed that total testicular volume >3.93 mL, left testis volume >1.79 mL, and neutrophil-to-lymphocyte ratio ≤1.82 were significantly associated with PSR.

CONCLUSIONS

mTESE-ICSI is a feasible method for KS patients to have a child, and total testicular volume, left testis volume, and neutrophil-to-lymphocyte ratio might be predictors of successful SR.

Metabolic and Nutritional Aspects in Paediatric Patients with Klinefelter Syndrome: A Narrative Review

Klinefelter syndrome is the most common sex chromosomal aneuploidy in males. It is well known that patients with this syndrome have greater mortality and morbidity compared to the general population due to cardiovascular diseases and endocrine metabolism disorders. This augmented risk is due both to hypogonadism and to the syndrome itself. Therefore, correct hormonal replacement therapy and early primary prevention are crucial to these patients. Even though different studies are available on this topic in adult patients, only a few authors have focused on the paediatric population. Thus, in this narrative review, we report the current knowledge of metabolic and nutritional aspects in children with Klinefelter syndrome.

Metabolic Profile in a Cohort of Young Sicilian Patients with Klinefelter's Syndrome: The Role of Irisin

Klinefelter's syndrome (KS) is the main cause of hypogonadism and infertility in men and is often related to obesity, metabolic syndrome, and diabetes. The purpose of our real-life observational study was to investigate the metabolic and anthropometric parameters in a population of patients with Klinefelter syndrome compared to a group of healthy age-matched subjects. Methods. In our study, 25 consecutive Caucasian adult outpatients (age range 21-52 years, mean age 32.9 ± 12.2) with KS in testosterone replacement therapy and 30 healthy men (age range 25-45 years, mean age 32.4 ± 7.62) were studied. In both groups of subjects, anthropometric indices, lipid profile, glucose metabolic parameters, HbA1c, the homeostasis model assessment estimate of HOMA-insulin resistance (IR), and the insulin sensitivity index (ISI) were evaluated. In addition, we assessed the complete hormonal gonadic status and irisin values in both groups of patients. Results. No significant differences were found in BMI and total blood testosterone levels between KS and control subjects. Patients with KS had significantly higher values of WC (p=0.028), HbA1c (p=0.018), HOMA-IR (p < 0.001), FSH (p < 0.001), LH (p < 0.001), estradiol (p=0.001), and irisin (p=0.029) and significantly lower HDL-cholesterol (p=0.002), AMH (p < 0.001), inhibin B (p < 0.001), and ISI-Matsuda (p < 0.001) compared to healthy controls. Univariate analysis revealed an inverse correlation between irisin and ISI-Matsuda (r = -0.128; p=0.010). These data were then confirmed in multivariate analysis. Conclusions. KS is characterized by early development of metabolic syndrome and in particular by alterations of the glucose metabolism, independently of testosterone levels serum and BMI. Irisin blood levels of Klinefelter's patients are higher than in healthy subjects and positively correlate with the degree of insulin resistance.

Glucose metabolic disorder in Klinefelter syndrome: a retrospective analysis in a single Chinese hospital and literature review

BACKGROUND

We aimed to investigate the clinical characteristics and islet β-cell function in patients with Klinefelter syndrome (KS) and hyperglycemia.

METHODS

This is a retrospective study. In total, 22 patients diagnosed with KS were identified from the electronic medical record system, including 9 patients with hyperglycemia (total patients with hyperglycemia, THG-KS group) and 5 hyperglycemic KS patients with oral glucose tolerance test (OGTT) results (HG-KS group). An additional 5 subjects with hyperglycemia and 5 normal glucose tolerance (NGT) subjects matched based on body mass index were included as the HG group and NGT group, respectively. Data from clinical and laboratory examinations were collected. We further performed a literature review of KS and hyperglycemia.

RESULTS

We found that KS patients developed abnormal glucose metabolism earlier in life than those without KS, and the median age was 17 years, ranging from 10 years to 19 years. Six of 17 (35.3%) patients were diagnosed with diabetes mellitus and 3 of 17 (17.6%) patients were diagnosed with prediabetes. Among 10 patients with both fasting blood glucose and insulin results recorded, there were 8 out of 17 (47.1%) KS patients had insulin resistance. The prevalence of hypertension and dyslipidemia was higher in patients with hyperglycemia and KS than in patients with NGT KS. Compared with the HG group, insulin sensitivity levels were lower in HG-KS group, whereas homeostasis model assessment of β-cell function levels (p = 0.047) were significantly, indicating higher insulin secretion levels in the HG-KS group.

CONCLUSIONS

KS patients develop hyperglycemia earlier in life than those without KS and show lower insulin sensitivity and higher insulin secretion. These patients also have a higher prevalence of other metabolic diseases and may have different frequencies of developing KS-related symptoms.

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.

Klinefelter syndrome in an adolescent with severe obesity, insulin resistance, and hyperlipidemia, successfully treated with testosterone replacement therapy

Klinefelter syndrome (KS) is a sex chromosome disorder characterized by the presence of one or more extra X chromosomes. KS is well known by the common karyotype 47, XXY and presents as male infertility with hypogonadism in adults. Pediatric patients with KS commonly show neurodevelopmental disorders and cryptorchidism. We have reported a case of a 14-yr-old boy with KS and severe obesity (body mass index, 38.1 kg/m²), insulin (IRI) resistance (homeostatic model assessment 1 IRI resistance, 9.26), hyperlipidemia (serum low-density lipoprotein cholesterol level, 192 mg/dL; serum triglyceride level, 239 mg/dL), hypergonadotropic hypogonadism, and learning difficulties. The karyotype was 47, XXY, t(4;5) (q21.2;q32). Initially, he was unwilling to accept dietary restrictions and perform physical exercise against obesity. Testosterone replacement therapy was initiated at 16 years of age, which successfully improved the body composition, IRI resistance, and hyperlipidemia and increased the serum testosterone levels. Additionally, he adhered to recommendations for exercise and dietary restrictions. Patients with KS have risks of obesity and metabolic syndrome with sarcopenic conditions due to hypergonadotropic hypogonadism. Pediatricians should be aware of KS as a primary disease causing obesity. Testosterone replacement therapy could help ameliorate obesity and its comorbidities in patients with obesity and KS.

At what age should we attempt to retrieve sperm from males with Klinefelter syndrome

Klinefelter syndrome (KS) is a common disorder and almost every clinician in almost every sub-specialty of medicine will knowingly or unwittingly treat boys or men with a 47,XXY chromosomal constitution. Although there are numerous aspects of KS worthy of discussion, this contribution will focus specifically on the controversial, and as yet unresolved, issue of whether it is advantageous to harvest testis tissue from peri-pubertal or adolescent boys with KS in a heroic effort to preserve that child’s chances of reproduction in his future adult life. What would be the rationale for that, how does the biology of spermatogenesis in the Klinefelter testis impact that decision, and what does the data show? The answer, assembled from a selection of seemingly disparate sources and directions, appears to be “No”. We do not have to advocate for an aggressive approach, we do not have to preemptively preserve future fertility. We can justifiably wait until adulthood with equivalent chances of success.

Primary aldosteronism in Klinefelter's syndrome: two cases

SUMMARY

Primary aldosteronism (PA) is more common than expected. Aberrant adrenal expression of luteinizing hormone (LH) receptor in patients with PA has been reported; however, its physiological role on the development of PA is still unknown. Herein, we report two unique cases of PA in patients with untreated Klinefelter's syndrome, characterized as increased serum LH, suggesting a possible contribution of the syndrome to PA development. Case 1 was a 39-year-old man with obesity and hypertension since his 20s. His plasma aldosterone concentration (PAC) and renin activity (PRA) were 220 pg/mL and 0.4 ng/mL/h, respectively. He was diagnosed as having bilateral PA by confirmatory tests and adrenal venous sampling (AVS). Klinefelter's syndrome was suspected as he showed gynecomastia and small testes, and it was confirmed on the basis of a low serum total testosterone level (57.3 ng/dL), high serum LH level (50.9 mIU/mL), and chromosome analysis. Case 2 was a 28-year-old man who had untreated Klinefelter's syndrome diagnosed in his childhood and a 2-year history of hypertension and hypokalemia. PAC and PRA were 247 pg/mL and 0.3 ng/mL/h, respectively. He was diagnosed as having a 10 mm-sized aldosterone-producing adenoma (APA) by AVS. In the APA, immunohistochemical analysis showed co-expression of LH receptor and CYP11B2. Our cases of untreated Klinefelter's syndrome complicated with PA suggest that increased serum LH levels and adipose tissues, caused by primary hypogonadism, could contribute to PA development. The possible complication of PA in hypertensive patients with Klinefelter's syndrome should be carefully considered.

LEARNING POINTS

The pathogenesis of primary aldosteronism is still unclear. Expression of luteinizing hormone receptor has been reported in aldosterone-producing adenoma. Serum luteinizing hormone, which is increased in patients with Klinefelter's syndrome, might contribute to the development of primary aldosteronism.

Klinefelter Syndrome and Diabetes

PURPOSE OF REVIEW

Klinefelter syndrome (KS) is associated with increased insulin resistance and high rates of type 2 diabetes (T2DM). Our aim was to review what is known about the prevalence of diabetes in men with KS, potential mechanisms underlying the observed metabolic phenotype, and the data that are available to guide treatment decisions.

RECENT FINDINGS

The increased prevalence of T2DM seen in men with KS appears to be the result of multiple mechanisms including increased truncal adiposity and socioeconomic disadvantages, but it is likely not a direct consequence of hypogonadism alone. No randomized trials have been conducted to evaluate the impact of testosterone replacement therapy on T2DM in men with KS, but observational data suggest that testosterone replacement is not associated with lower rates of diabetes or improved glycemic control. Metabolic derangements are common in KS, but treatment strategies specific to this population are lacking. Early lifestyle and dietary interventions are likely important. Additional research is needed to dissect the complex interaction between genotype and metabolic phenotype. Collaboration between academic centers caring for men with KS is needed to facilitate the development of evidence-based clinical practice guidelines, which would inform optimal screening and treatment strategies for this patient population.

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.

Sex differences in metabolism and cardiometabolic disorders

PURPOSE OF REVIEW

Sex differences are pervasive in metabolic and cardiovascular traits, yet they have often been ignored in human and animal model research. Sex differences can arise from reversible hormonal effects, from irreversible organizational (developmental) processes, and from gene expression differences from the X and Y chromosomes. We briefly review our current understanding of the impact of these factors in metabolic traits and disorders, with an emphasis on the recent literature.

RECENT FINDINGS

Novel sex differences continue to be identified for metabolic and cardiovascular traits. For example, it is now clear that gut microbiota tend to differ between men and women, with potentially large implications for disease susceptibility. Also, tissue-specific gene regulation differs between men and women, contributing to differential metabolism. These new insights will open up personalized therapeutic avenues for cardiometabolic diseases.

SUMMARY

Sex differences in body fat distribution, glucose homeostasis, insulin signaling, ectopic fat accumulation, and lipid metabolism during normal growth and in response to hormonal or nutritional imbalance are mediated partly through sex hormones and the sex chromosome complement. Most of these differences are mediated in a tissue-specific manner. Important future goals are to better understand the interactions between genetic variation and sex differences, and to bring an understanding of sex differences into clinical practice.

Klinefelter Syndrome: Integrating Genetics, Neuropsychology, and Endocrinology

Although first identified over 70 years ago, Klinefelter syndrome (KS) continues to pose substantial diagnostic challenges, as many patients are still misdiagnosed, or remain undiagnosed. In fact, as few as 25% of patients with KS are accurately diagnosed and most of these diagnoses are not made until adulthood. Classic characteristics of KS include small testes, infertility, hypergonadothropic hypogonadism, and cognitive impairment. However, the pathophysiology behind KS is not well understood, although genetic effects are also thought to play a role. For example, recent developments in genetics and genomics point to a fundamental change in our understanding of KS, with global epigenetic and RNA expression changes playing a central role for the phenotype. KS is also associated with more general health markers, including higher morbidity and mortality rates and lower socioeconomic status (which likely affect both morbidity and mortality). In addition, hypogonadism is associated with greater risk of metabolic syndrome, type 2 diabetes, cardiovascular disease, breast cancer, and extragonadal germ cell tumors. Medical treatment typically focuses on testosterone replacement therapy (TRT), although the effects of this therapy have not been studied rigorously, and future studies need to evaluate the effects of TRT on metabolic risk and neurocognitive outcomes. This review presents a comprehensive interdisciplinary examination of recent developments in genetic, endocrine, and neurocognitive science, including the study of animal models. It provides a number of recommendations for improving the effectiveness of research and clinical practice, including neonatal KS screening programs, and a multidisciplinary approach to KS treatment from childhood until senescence.

Klinefelter syndrome, insulin resistance, metabolic syndrome, and diabetes: review of literature and clinical perspectives

PURPOSE

Klinefelter syndrome (KS), the most frequent chromosomic abnormality in males, is associated with hypergonadotropic hypogonadism and an increased risk of cardiovascular diseases (CVD). The mechanisms involved in increasing risk of cardiovascular morbidity and mortality are not completely understood. This review summarises the current understandings of the complex relationship between KS, metabolic syndrome and cardiovascular risk in order to plan future studies and improve current strategies to reduce mortality in this high-risk population.

METHODS

We searched PubMed, Web of Science, and Scopus for manuscripts published prior to November 2017 using key words "Klinefelter syndrome" AND "insulin resistance" OR "metabolic syndrome" OR "diabetes mellitus" OR "cardiovascular disease" OR "testosterone". Manuscripts were collated, studied and carried forward for discussion where appropriate.

RESULTS

Insulin resistance, metabolic syndrome, and type 2 diabetes are more frequently diagnosed in KS than in the general population; however, the contribution of hypogonadism to metabolic derangement is highly controversial. Whether this dangerous combination of risk factors fully explains the CVD burden of KS patients remains unclear. In addition, testosterone replacement therapy only exerts a marginal action on the CVD system.

CONCLUSION

Since fat accumulation and distribution seem to play a relevant role in triggering metabolic abnormalities, an early diagnosis and a tailored intervention strategy with drugs aimed at targeting excessive visceral fat deposition appear necessary in patients with KS.

Sex differences in obesity, lipid metabolism, and inflammation-A role for the sex chromosomes?

BACKGROUND

Sex differences in obesity and related diseases are well established. Gonadal hormones are a major determinant of these sex differences. However, sex differences in body size and composition are evident prior to exposure to gonadal hormones, providing evidence for gonadal-independent contributions attributable to the XX or XY sex chromosome complement. Large-scale genetic studies have revealed male/female differences in the genetic architecture of adipose tissue amount and anatomical distribution. However, these studies have typically neglected the X and Y chromosomes.

SCOPE OF THE REVIEW

Here we discuss how the sex chromosome complement may influence obesity, lipid levels, and inflammation. Human sex chromosome anomalies such as Klinefelter syndrome (XXY), as well as mouse models with engineered alterations in sex chromosome complement, support an important role for sex chromosomes in obesity and metabolism. In particular, the Four Core Genotypes mouse model-consisting of XX mice with either ovaries or testes, and XY mice with either ovaries or testes-has revealed an effect of X chromosome dosage on adiposity, hyperlipidemia, and inflammation irrespective of male or female gonads. Mechanisms may include enhanced expression of genes that escape X chromosome inactivation.

MAJOR CONCLUSIONS

Although less well studied than effects of gonadal hormones, sex chromosomes exert independent and interactive effects on adiposity, lipid metabolism, and inflammation. In particular, the presence of two X chromosomes has been associated with increased adiposity and dyslipidemia in mouse models and in XXY men. The enhanced expression of genes that escape X chromosome inactivation may contribute, but more work is required.

[Klinefelter syndrome and cardiovascular risk]

We present a 45-year-old patient with Klinefelter syndrome, with a history of type 2 diabetes mellitus, obesity, dyslipidemia, obstructive sleep apnoea syndrome and masked arterial hypertension. The purpose of this presentation is to draw attention to the increased cardiovascular risk in these patients and to review the data in the literature on this risk.

Sex differences in obesity: X chromosome dosage as a risk factor for increased food intake, adiposity and co-morbidities

Obesity is a world-wide problem, and a risk factor for cardiovascular disease, diabetes, cancer and other diseases. It is well established that sex differences influence fat storage. Males and females exhibit differences in anatomical fat distribution, utilization of fat stores, levels of adipose tissue-derived hormones, and obesity co-morbidities. The basis for these sex differences may be parsed into the effects of male vs. female gonadal hormones and the effects of XX vs. XY chromosome complement. Studies employing mouse models that allow the distinction of gonadal from chromosomal effects have revealed that X chromosome dosage influences food intake, which in turn affects adiposity and the occurrence of adverse metabolic conditions such as hyperinsulinemia, hyperlipidemia, and fatty liver. The identification of X chromosome dosage as a player in the behavior and physiology related to obesity suggests novel molecular mechanisms that may underlie sex differences in obesity and metabolism.