BACKGROUND: Klinefelter syndrome (47, XXY) is the most common sex chromosome aneuploidy. In addition to male hypergonadotropic hypogonadism, a wide range of neurodevelopmental disorders, anxiety and affective symptoms have been reported in a substantial proportion of cases.
METHODS: We document the rare case of a 43-year-old man diagnosed with Klinefelter syndrome and co-morbid Gilles de la Tourette syndrome. He presented with multiple motor and vocal tics since adolescence, as well as anxiety and affective symptoms as his main tic-exacerbating factors. Tic severity was rated as marked (Yale Global Tic Severity Scale score of 78/100), and recommendations for the treatment of both tics and psychiatric co-morbidities were formulated.
CONCLUSIONS: Neurodevelopmental tics in the context of Klinefelter syndrome have been previously documented in three cases only. Gilles de la Tourette syndrome is 3-4 times more common in males than females and its etiological factors include multiple genetic components (genetic heterogeneity). Our case report widens the spectrum of neurodevelopmental disorders observed in the context of Klinefelter syndrome and contributes to genetic research on the role of the X chromosome in the pathophysiology of tic disorders.

UNASSIGNED: To examine the link between tremor and sex chromosome abnormalities, emphasizing the necessity of comprehensive physical examination.
UNASSIGNED: An 18-year-old man exhibited an isolated action tremor in both hands. Despite having no familial history of tremors and no identifiable secondary causes, his tall stature and learning difficulties suggested a genetic origin. His karyotype confirmed the diagnosis of Jacob\'s syndrome (XYY syndrome). Therapies with primidone and propranolol were ineffective for his tremor.
UNASSIGNED: Tremor can be caused by various conditions, and aneuploidies might often be overlooked as a cause. They should be considered in young patients with concrete phenotypes and negative familiar history of tremors. Karyotyping is a cost-effective diagnostic tool crucial for genetic counselling. Common treatments for tremors often yield unsatisfactory results in these cases.

Aminoacyl-tRNA synthetases play a pivotal role in catalyzing the precise coupling of amino acids with their corresponding tRNAs. Among them, Tyrosyl tRNA synthetase, encoded by the YARS1 gene, facilitates the aminoacylation of tyrosine to its designated tRNA. Heterozygous variants in the YARS1 gene have been linked to autosomal dominant Charcot-Marie-Tooth type C, while recent findings have unveiled biallelic YARS1 variants leading to an autosomal recessive multisystemic disorder in several cases. In this report, we present a novel case characterized by dysmorphic facies, and multisystemic symptoms, prominently encompassing neurological issues and a microarray conducted shortly after birth revealed 47, XXY. Utilizing whole exome sequencing, we uncovered a paternally inherited likely pathogenic variant (c.1099C > T, p.Arg367Trp), previously reported, coinciding with the father\'s history of hearing loss and neurological symptoms. Additionally, a maternally inherited variant of uncertain significance (c.782T > G, p.Leu261Arg), previously unreported, was identified within the YARS1 gene. The observed phenotypes and the presence of compound heterozygous results align with the diagnosis of an autosomal recessive disorder associated with YARS1. Through our cases, the boundaries of this emerging clinical entity are broadened. This instance underscores the significance of comprehensive genetic testing in patients exhibiting intricate phenotypes.

To investigate sleep among men with Klinefelter syndrome (KS).
We compared the sleep domains latency, disturbance, and efficiency in 30 men with KS (M age = 36.7 years, SD = 10.6) to 21 age-matched non-KS controls (M age = 36.8 years, SD = 14.4). Actigraphs were used to objectively measure sleep across 7 days and nights. Participants also completed a sleep diary over the same period, and the Pittsburgh Sleep Quality Index (PSQI).
The mean correlation between the objective and subjective sleep measures was lower for the KS sample (M r = .15) than for controls (M r = .34). Sleep disturbance was significantly larger in the KS sample, as measured by actigraphy (p = .022, d = 0.71) and the PSQI (p = .037, d = 0.61). In regression models predicting sleep domains from KS status, age, educational level, vocational status, IQ, and mental health, KS status was not a significant predictor. Higher age was associated with more actigraphy-measured sleep disturbance. Higher educational level and being employed were associated with better sleep efficiency.
Sleep disturbance may be a particular problem for men with KS and should be measured with complimentary methods.

The overall incidence of sex chromosome aneuploidies is approximately 1 per 500 live-born infants, but far more common at conception. I shall review the fertility aspects of the sex chromosome trisomies, XXY, XYY, and XXX, with special reference to the karyotype 45,X/47,XXX. Each has a \'specific\' (but variable) phenotype but may be modified by mosaicism. Although the alterations in the hypothalamic-pituitary-gonadal axis are important (and discussed), the emphasis here is on potential fertility and if one might predict that at various epochs within an individual\'s life span: fetal, \'mini\'-puberty, childhood, puberty, and adulthood. The reproductive axis is often affected in females with the 47,XXX karyotype with diminished ovarian reserve and accelerated loss of ovarian function. Fewer than 5% of females with Turner syndrome have the 45,X/47,XXX karyotype. They have taller stature and less severe fertility issues compared to females with the 45,X or other forms of Turner syndrome mosaicism. For the 47,XXY karyotype, non-obstructive azoospermia is almost universal with sperm retrieval by micro-testicular sperm extraction possible in slightly fewer than half of the men. Men with the 47,XYY karyotype have normal to large testes and much less testicular dysfunction than those with the 47,XXY karyotype. They do have a slight increase in infertility compared to the reference population but not nearly as severe as those with the 47,XXY karyotype. Assisted reproductive technology, especially micro-testicular sperm extraction, has an important role, especially for those with 47,XXY; however, more recent data show promising techniques for the in vitro maturation of spermatogonial stem cells and 3D organoids in culture. Assisted reproductive technology is more complex for the female, but vitrification of oocytes has shown promising advances.

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.
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).
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.
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.

BACKGROUND: Only few studies have assessed sexual dysfunction in men with Klinefelter syndrome (KS).
OBJECTIVE: 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.
METHODS: 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.
CONCLUSIONS: While DL would largely reflect an androgen deficiency, in older men with KS, erectile function should be assessed irrespective of testosterone levels.
UNASSIGNED: 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.

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.
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.
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 (Wattmax; 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.
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.

Klinefelter syndrome (KS, 47,XXY) is a common sex chromosome aneuploidy in males that is associated with a wide range of cognitive, social and emotional characteristics. The neural bases of these symptoms, however, are unclear. Brain structure in 19 pre- or early-pubertal boys with KS (11.5 ± 1.8 years) and 22 typically developing (control) boys (8.1 ± 2.3 years) was examined using surface-based analyses of cortical gray matter volume, thickness and surface area. Boys in the KS group were treatment-naïve with respect to testosterone replacement therapy. Reduced volume in the insula and dorsomedial prefrontal cortex was observed in the KS relative to the TD group, as well as increased volume in the parietal, occipital and motor regions. Further inspection of surface-based metrics indicated that whereas KS-associated increases in volume were driven by differences in thickness, KS-associated reductions in volume were associated with decreases in surface area. Exploratory analyses additionally indicated several correlations between brain structure and behavior, providing initial support for a neural basis of cognitive and emotional symptoms of this condition. Taken together, these data add support for a neuroanatomical phenotype of KS and extend previous studies through clarifying the precise neuroanatomical structural characteristics of that give rise to volumetric alterations.

Only few studies have assessed sexual dysfunction in men with Klinefelter syndrome (KS).
To define pooled prevalence estimates and correlates of erectile dysfunction (ED) and decreased libido (DL) in KS.
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.
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.
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.
While DL would largely reflect an androgen deficiency, in older men with KS, erectile function should be assessed irrespective of testosterone levels.
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.
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.