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.

Klinefelter syndrome: The characterization of the clinical and sociological features of 51 patients.

INTRODUCTION: Klinefelter syndrome is the most frequently found aneuploidy among male patients. Its clinical presentation is very heterogeneous, and thus poses a challenge for a timely diagnosis. METHODS: A retrospective study was carried out with 51 consecutively selected patients diagnosed with Klinefelter Syndrome from Jan/2010 to Dec/2019. The karyotypes were identified using high resolution GTL banding at the Genetics Department. Multiple clinical and sociological parameters were studied by collecting data from the clinical records. RESULTS: 44 (86%) of the 51 patients presented a classical karyotype (47,XXY) and 7 (14%) showed evidence of mosaicism. The mean age at diagnosis was 30.2±14.3 years old. Regarding the level of education (N=44), 26 patients (59.1%) had no secondary education, with 5 (11.4%) patients having concluded university studies. Almost two thirds of the sample revealed learning difficulties (25/38) and some degree of intellectual disability was present in 13.6% (6/44). Half of the patients were either non-qualified workers (19.6%) or workers in industry, construction, and trades (30.4%), which are jobs that characteristically require a low level of education. The proportion of unemployed patients was 6.5%. The main complaints were infertility (54.2%), followed by hypogonadism-related issues (18.7%) and gynecomastia (8.3%). 10 patients (23.8%, N=42) were biological parents. With regards the question of fertility, assisted reproductive techniques were used in 39.6% of the studied subjects (N=48), with a success rate (a take home baby) of 57.9% (11/19), 2 with donor sperm and 9 with the patients' own gametes. Only 41% of the patients (17/41) were treated with testosterone. CONCLUSION: This study identifies the most important clinical and sociological findings of Klinefelter syndrome patients that should be considered when deciding workout and disease management.

The Klinefelter Syndrome and Testicular Sperm Retrieval Outcomes.

Klinefelter syndrome (KS), caused by the presence of an extra X chromosome, is the most prevalent chromosomal sexual anomaly, with an estimated incidence of 1:500/1000 per male live birth (karyotype 47,XXY). High stature, tiny testicles, small penis, gynecomastia, feminine body proportions and hair, visceral obesity, and testicular failure are all symptoms of KS. Endocrine (osteoporosis, obesity, diabetes), musculoskeletal, cardiovascular, autoimmune disorders, cancer, neurocognitive disabilities, and infertility are also outcomes of KS. Causal theories are discussed in addition to hormonal characteristics and testicular histology. The retrieval of spermatozoa from the testicles for subsequent use in assisted reproduction treatments is discussed in the final sections. Despite testicular atrophy, reproductive treatments allow excellent results, with rates of 40-60% of spermatozoa recovery, 60% of clinical pregnancy, and 50% of newborns. This is followed by a review on the predictive factors for successful sperm retrieval. The risks of passing on the genetic defect to children are also discussed. Although the risk is low (0.63%) when compared to the general population (0.5-1%), patients should be informed about embryo selection through pre-implantation genetic testing (avoids clinical termination of pregnancy). Finally, readers are directed to a number of reviews where they can enhance their understanding of comprehensive diagnosis, clinical care, and fertility preservation.

Klinefelter Syndrome: What should we tell prospective parents?

Klinefelter syndrome (KS) or 47,XXY is the most common sex chromosome aneuploidy (SCA), occurring at a prevalence of 1 in 600 male pregnancies. Historically, only 25% of individuals with KS came to medical attention, for a range of issues across the life course including under-virilisation at birth, developmental and social concerns in childhood, absence, delay or arrest of puberty in adolescence or infertility in adulthood. Our understanding of the phenotypic spectrum of KS has been largely influenced by this ascertainment bias. With increasing uptake of antenatal noninvasive prenatal testing (NIPT), a corresponding increase in identification of KS has been documented. Population-based longitudinal data from infancy to adulthood on these individuals is lacking, which impedes balanced antenatal genetic counselling and raises issues for prospective parents and clinicians alike.

Neuroimmune Dysregulation in Prepubertal and Adolescent Individuals Affected by Klinefelter Syndrome.

BACKGROUND: The syndrome Klinefelter syndrome (KS) is a genetic disorder due to an extra X chromosome in males. Many cases remain undiagnosed until the onset of major manifestations, which include hypergonadotropic hypogonadism and infertility. This condition is associated with many comorbidities that involve the cardiovascular, endocrine, and immune systems. Last but not the least, individuals with KS show a high risk of developing psychiatric and mood disorders in adult age. OBJECTIVE: While many studies are accessible on KS in adult individuals, the neuroinflammatory condition in adolescent and prepubertal KS individuals is not fully known. METHODS: Our study aims to evaluate in prepubertal and adolescent KS individuals, for the first time, the levels of the serum of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), cytokines having subtle roles in oxidative processes, and neuroinflammation with respect to the levels of TNF-α, TGF-ß, MCP-1, IL-1α, IL-2, IL-6, IL-10, and IL-12 and oxidative stress by employing free oxygen radicals defense and free oxygen radicals test. RESULTS: We found no changes in NGF and oxidative stress parameters, but BDNF decreased compared to healthy children. Quite interestingly, our data showed reduced levels of IL-2, IL-1α, IL- 12, IL-10, and IL-6 in prepubertal KS children. CONCLUSION: The present study discloses disrupted immune system and neurotrophin pathways in KS children.

Oncological diseases in Klinefelter Syndrome: an overview.

Epidemiological studies have highlighted a higher incidence of morbidity and mortality among individuals with Klinefelter's Syndrome (KS), however, the relative impact of oncological diseases on KS subjects is still uncertain. While some malignancies (e.g., hematological and lung cancers) may show an increased prevalence in the KS population, only a few rare tumors (i.e., extragonadal germ cell tumors [GCTs] and male breast cancer [MBC]) seem to follow this trend. Additionally, hormonal and genetic determinants may be involved in the pathogenesis of neoplasia in KS, even if subjects affected by this syndrome generally show lower incidence of prostate cancer along with lower disease-specific mortality despite testosterone replacement therapy (TRT). This review deals with the pathophysiological and clinical aspects of neoplastic diseases occurring in KS.

State-wide increase in prenatal diagnosis of klinefelter syndrome on amniocentesis and chorionic villus sampling: Impact of non-invasive prenatal testing for sex chromosome conditions.

BACKGROUND: To analyze population-based trends in the prenatal diagnosis of sex chromosome aneuploidy (SCA) since the availability of non-invasive prenatal testing (NIPT). METHODS: Retrospective state-wide data for all prenatal diagnoses performed <25 weeks gestation from 2005 to 2020 in Victoria, Australia. Non-invasive prenatal testing became locally available from 2012. The prenatal diagnosis rates of SCA as proportions of all prenatal diagnostic tests and all births were calculated. Statistical significance was assessed with the χ2 test for trend, with p < 0.05 considered significant. RESULTS: 46,518 amniocentesis and chorionic villus sampling were performed during the study period, detecting 617 SCAs. There was a significant increase in the rate of prenatal SCAs from 5.8 per 10,000 births in 2005 to 8.7 per 10,000 births in 2020 (p < 0.0001). This increase was predominantly due to 47,XXY cases, 91% of which were ascertained via positive NIPT for this condition in 2020. The prenatal diagnosis rate of 47,XXY significantly increased from 0.8 per 10,000 births in 2005 to 4.3 per 10,000 births in 2020 (p < 0.0001). CONCLUSION: Screening for SCAs using NIPT has directly led to an increase in their prenatal diagnosis on a population-wide basis, especially 47,XXY. This has implications for clinician education, genetic counselling, and pediatric services.

Body composition, trabecular bone score and vertebral fractures in subjects with Klinefelter syndrome.

BACKGROUND: Klinefelter syndrome (KS) frequently causes skeletal fragility characterized by profound alterations in bone microstructure with increased risk of fractures. Increased body fat mass associated with decreased body lean mass are frequent features of KS with possible detrimental effects on skeletal health. In this cross-sectional study, we evaluated the associations between body composition parameters, vertebral fractures (VFs) and trabecular bone score (TBS) in adult subjects with KS. METHODS: Seventy-one adult males (median age 41 years, range 18-64) with 47, XXY KS were consecutively enrolled by two Endocrinology and Andrology Units (IRCCS Humanitas Research Hospital in Milan and ASST Spedali Civili in Brescia). Dual-energy X-ray absorptiometry (DXA) was performed to assess bone mineral density (BMD) at lumbar spine, femoral neck and total hip, TBS and body composition. Prevalence of VFs was assessed by quantitative morphometry on lateral spine X-rays. RESULTS: VFs were detected in 14 patients (19.7%), without significant association with low BMD (p = 0.912). In univariate logistic regression analysis, VFs were significantly associated with truncal/leg fat ratio (OR 2.32 per tertile; 95% CI 1.05-5.15; p = 0.038), whereas impaired TBS (detected in 23.4% of subjects) was associated with older age at study entry (p = 0.001) and at diagnosis of disease (p = 0.015), body mass index (BMI; p = 0.001), waist circumference (p = 0.007), fat mass index (FMI; p < 0.001), FMI/lean mass index (LMI) ratio (p = 0.001). Prevalence of VFs was not significantly different between subjects with impaired TBS as compared to those with normal TBS (26.7 vs. 18.4%; p = 0.485). Skeletal end-points were not significantly associated with duration of testosterone replacement therapy and serum testosterone and 25hydroxyvitamin D values. CONCLUSION: Body composition might influence bone quality and risk of VFs in subjects with KS.

Detection and characterization of male sex chromosome abnormalities in the UK Biobank study.

PURPOSE: The study aimed to systematically ascertain male sex chromosome abnormalities, 47,XXY (Klinefelter syndrome [KS]) and 47,XYY, and characterize their risks of adverse health outcomes. METHODS: We analyzed genotyping array or exome sequence data in 207,067 men of European ancestry aged 40 to 70 years from the UK Biobank and related these to extensive routine health record data. RESULTS: Only 49 of 213 (23%) of men whom we identified with KS and only 1 of 143 (0.7%) with 47,XYY had a diagnosis of abnormal karyotype on their medical records or self-report. We observed expected associations for KS with reproductive dysfunction (late puberty: risk ratio [RR] = 2.7; childlessness: RR = 4.2; testosterone concentration: RR = -3.8 nmol/L, all P < 2 × 10-8), whereas XYY men appeared to have normal reproductive function. Despite this difference, we identified several higher disease risks shared across both KS and 47,XYY, including type 2 diabetes (RR = 3.0 and 2.6, respectively), venous thrombosis (RR = 6.4 and 7.4, respectively), pulmonary embolism (RR = 3.3 and 3.7, respectively), and chronic obstructive pulmonary disease (RR = 4.4 and 4.6, respectively) (all P < 7 × 10-6). CONCLUSION: KS and 47,XYY were mostly unrecognized but conferred substantially higher risks for metabolic, vascular, and respiratory diseases, which were only partially explained by higher levels of body mass index, deprivation, and smoking.

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.

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.

Clinical features and prevalence of Klinefelter syndrome in transgender individuals: A systematic review.

OBJECTIVE: Previous studies have suggested a higher prevalence of Klinefelter syndrome amongst transgender individuals. We undertook a systematic review to determine the prevalence of Klinefelter syndrome amongst transgender individuals presumed male at birth and summarize the clinical features and potential treatment implications for individuals with Klinefelter syndrome commencing gender-affirming hormone therapy. DESIGN: Using preferred reporting items for systematic review and meta-analysis guidelines, we searched EMBASE, MEDLINE and the Cochrane Central Register of Controlled Trials (CENTRAL) up to 31 December 2021. All studies reporting on the prevalence or clinical features of transgender individuals with Klinefelter syndrome were included. This study is registered with the International Prospective Register of Systematic Reviews, number CRD42021227916. RESULTS: Our search strategy retrieved 11 cohort studies comprising 1376 transgender individuals. In all, 14 of 1376 (1.02%) individuals were diagnosed with Klinefelter syndrome. Based on the seven studies in which karyotype was undertaken in all individuals, the prevalence is 9/1013 (0.88%; 95% CI, 0.41%-1.68%). Case reports highlight unique treatment considerations in this population, including azoospermia, venous thromboembolism, and monitoring of breast cancer and bone health. CONCLUSIONS: Compared to the general population, observational studies document a higher prevalence of Klinefelter syndrome amongst transgender individuals, though underdiagnosis in the general population limits conclusions. Routine karyotype in transgender people initiating gender-affirming hormone therapy is not supported unless clinical features of Klinefelter syndrome, such as small testicular volume, or hypergonadotropic hypogonadism are present. Transgender individuals with Klinefelter syndrome need to manage a unique risk profile if they desire feminizing gender-affirming hormone therapy.

Population-based Assessment of Cardiometabolic-related Diagnoses in Youth With Klinefelter Syndrome: A PEDSnet Study.

CONTEXT: Diabetes and cardiovascular diseases are common among men with Klinefelter syndrome (KS) and contribute to high morbidity and mortality. OBJECTIVE: To determine if cardiometabolic-related diagnoses are more prevalent among youth with KS than matched controls in a large population-based cohort. METHODS: Secondary data analysis of electronic health records from 6 pediatric institutions in the United States (PEDSnet). Patients included all youth with KS in the database (n = 1080) and 4497 youth without KS matched for sex, age (mean 13 years at last encounter), year of birth, race, ethnicity, insurance, site, and duration of care (mean 7 years). The main outcome measures were prevalence of 5 cardiometabolic-related outcomes: overweight/obesity, dyslipidemia, dysglycemia, hypertension, and liver dysfunction. RESULTS: The odds of overweight/obesity (OR 1.6; 95% CI 1.4-1.8), dyslipidemia (3.0; 2.2-3.9), and liver dysfunction (2.0; 1.6-2.5) were all higher in KS than in controls. Adjusting for covariates (obesity, testosterone treatment, and antipsychotic use) attenuated the effect of KS on these outcomes; however, boys with KS still had 45% greater odds of overweight/obesity (95% CI 1.2-1.7) and 70% greater odds of liver dysfunction (95% CI 1.3-2.2) than controls, and both dyslipidemia (1.6; 1.1-2.4) and dysglycemia (1.8; 1.1-3.2) were higher in KS but of borderline statistical significance when accounting for multiple comparisons. The odds of hypertension were not different between groups. CONCLUSION: This large, population-based cohort of youth with KS had a higher odds of most cardiometabolic-related diagnoses than matched controls.

Pre-test anxiety levels and postoperative pain in non-obstructive azoospermic patients: Is klinefelter syndrome a predisposing factor?

INTRODUCTION: Increased depression and anxiety incidence in infertile individuals treated with assisted reproductive techniques have been shown in studies. Postoperative pain perception after testicular sperm extraction (TESE) is thought to be related to preoperative anxiety in non-obstructive azoospermia (NOA). MATERIALS AND METHODS: Twenty patients with Klinefelter syndrome (KS) and twenty male patients with normal karyotype NOA planned for TESE under local anaesthesia due to azoospermia were included in the study. Spielberger State-Trait Anxiety Inventory (STAI-T and STAI-S) inventory was given to all patients 1 h before surgery. Postoperative pain evaluation was performed at 0, 30, 60 and 120 min with visual analogue scale (VAS). STAI-T inventory was given to the patients again 2 h after the procedure. RESULTS: Preoperative STAI-S and STAI-T scores and postoperative STAI-T scores of patients in the KS group were higher than those in the NOA group, and there was a significant difference in the statistical analysis between the two groups (p < 0.001). In the postoperative VAS scores, there was no statistical difference at the 0 and 120th min (p = 0.56 and p = 0.87, respectively); at the 30, 60 and 90th min there was a statistically significant difference between the two groups, especially in patients in the KS group (p < 0.05, p < 0.05, p < 0.01, respectively). CONCLUSION: The contribution of anxiety to pain perception should be kept in mind in azoospermic male patients before TESE, and additional measures should be taken considering that this may be experienced at a higher level in KS patients.

[Klinefelter syndrome: Advances in research].

Klinefelter syndrome (KS) is a most common chromosome abnormality and frequently leads to male infertility. In recent years, deeper insights have been gained into the treatment of KS in children, clinical manifestations of KS, as well as reproductive problems and pre- and postnatal screening of the disease. This article presents an overview of the epidemiology, clinical manifestations, pathophysiological mechanism, laboratory examination, drug therapy and application of assisted reproductive technology, and KS screening, aiming to provide some reference for KS-related clinical practice.

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 ß-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 ß-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.

Chromosome Abnormalities Related to Reproductive and Sexual Development Disorders: A 5-Year Retrospective Study.

Chromosomal abnormalities are the main genetic risk factor associated with reproductive and sexual development disorders (DSD). The goal of this study is to retrospectively evaluate the frequency of chromosomal aberrations in Moroccan subjects with problems of procreation or sexual ambiguity. A total of 1005 individuals, including 170 infertile couples, underwent cytogenetic analysis in the Cytogenetic Laboratory of the Pasteur Institute of Morocco. Heparinized blood samples were processed according to the standard karyotype method. A total (81.5%) of the patients studied had a normal karyotype, while the remaining (18.5%) patients had an abnormal karyotype. Female patients had more chromosomal abnormalities (52%) than male patients (48%). These chromosomal aberrations included 154 cases (83%) of sex chromosomal abnormalities, the most common being Turner's syndrome and Klinefelter's syndrome, and 31 cases (17%) had autosomal aberrations, especially chromosome 9 reversal (inv(9)(p12;q13)). The present data shows that among 170 couples, 10.6% had chromosomal abnormalities mainly involved in the occurrence of recurrent miscarriages. Genotype-phenotype correlations could not be made, and therefore, studies using more resolutive molecular biology techniques would be desirable.

Lessons of the month 3: Mosaic Klinefelter syndrome unveiled by acute vertebral fracture in a middle-aged man.

Klinefelter syndrome (KS) is the most common sex chromosome disorder in males. It is the result of two or more X chromosomes in a phenotypic male. In addition to primary hypogonadism affecting male sexual development, it is associated with a series of comorbidities such as osteoporosis, psychiatric and cognitive disorders, metabolic syndromes, and autoimmune diseases. A broad spectrum of phenotypes has been described and many cases remain undiagnosed throughout their lifespan. In this case report, we describe a case of mosaic KS unmasked by acute vertebral fracture.

49,XXXXY syndrome: A study of neurological function in this uncommon X and Y chromosomal disorder.

49,XXXXY is a rare chromosomal variation characterized by deficits in motor, language, and cognitive domains. This study reports on the neurological function and dysmorphic features in the largest cohort to date. Seventy-two boys with 49,XXXXY were evaluated on a variety of domains including a neurological examination and neuromotor assessments including the Beery Buktenica Developmental Test of Visual-Motor Integration, Sixth Edition, the Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III), and the Bruininks-Oseretsky Test of Motor Proficiency, Second Edition. Results supported previous literature by describing high occurrences of truncal and extremity hypotonia, which significantly impacts on motor milestones and ambulation in this population. The boys presented with dysmorphic features including epicanthal folds, frontal bossing, and synophrys. Visual perception skills were mildly impaired and cranial nerves were typically intact, however capabilities in motor coordination and fine motor precision were greatly delayed, supporting deficits in refined and controlled hand movements versus widespread visual deficits. Preschool boys treated with testosterone replacement had significantly increased scores when compared to the untreated group on the BSID-III Psychomotor Development Index, further supporting previous research indicating that testosterone replacement may have a positive impact on neurodevelopmental outcomes in males with additional X chromosomes. Boys with 49,XXXXY may benefit from hormonal treatment in conjunction with early intervention services to address their significant motor deficits.