Yearly Archives: 2020

Article Title: Klinefelter syndrome (KS): genetics, clinical phenotype and hypogonadism

Authors: Bonomi, Rochira, Pasquali, Balercia, Jannini, and Ferlin

Date of Publication: September 19, 2016

“Klinefelter Syndrome (KS) is characterized by an extreme heterogeneity in its clinical and genetic presentation. The relationship between clinical phenotype and genetic background has been partially disclosed; nevertheless, physicians are aware that several aspects concerning this issue are far to be fully understood. By improving our knowledge on the role of some genetic aspects as well as on the KS, patients’ interindividual differences in terms of health status will result in a better management of this chromosomal disease. The aim of this review is to provide an update on both genetic and clinical phenotype and their interrelationships.”

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Article Title: Strategies to improve early diagnosis of Klinefelter syndrome

Authors: Alberto Ferlin

Date of Publication: October 2020

“Klinefelter syndrome is the most frequent chromosome disorder in men, but it is largely undiagnosed or receives a late diagnosis in adulthood. This condition is characterized by an extra X-chromosome: approximately 80%-90% of patients with Klinefelter syndrome have a 47,XXY karyotype, 10%-20% mosaicisms of two different genetic lines such as 47,XXY/46,XY, isochromosome X, and higher number of X chromosomes. Although our knowledge on this syndrome substantially improved in last years, the diagnostic rate is still low. It has been estimated that only 25% to 40% of subjects with 47,XXY Klinefelter syndrome are ever diagnosed. A prenatal diagnosis is made in 15–20% of these cases, 10% is diagnosed before puberty, 15% at puberty, and the remaining 50–60% of cases are diagnosed during adulthood, typically in the course of a fertility workup, with some cases diagnosed even after the age of 50 or 60 years. Variants with higher number of X chromosomes (48,XXXY and 49,XXXXY) have more severe phenotype and distinct clinical features, which leads to higher diagnostic rate than 47,XXY. This manuscript refers to the most common form 47,XXY syndrome and strategies to improve early and timely diagnosis.”

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Article Title: Metabolic and cardiovascular risk factors in Klinefelter syndrome

Authors: Spaziani and Radicioni

Date of Publication: June 2020

“Klinefelter syndrome (KS), which normally presents with a 47,XXY karyotype, is the most common sex chromosome disorder in males. It is also the most common genetic cause of male infertility. KS subjects are typically tall, with small and firm testes, gynecomastia, broad hips, and sparse body hair, although a less evident presentation is also possible. KS is also characterized by a high prevalence of hypogonadism, metabolic syndrome (MetS) and cardiovascular disease. The aim of this article is to systematically review metabolic and the cardiovascular risk factors in KS patients. Hypogonadism has an important role in the pathogenesis of the changes in body composition (particularly visceral obesity) and hence of insulin resistance and MetS, but the association between KS and MetS may go beyond hypogonadism alone. From childhood, KS patients may show an increase in visceral fat with a reduction in lean body mass and an increase in glucose and impaired fat metabolism. Their increased incidence of congenital anomalies, epicardial adipose tissue, and thromboembolic disease suggests they have a higher risk of cardiovascular disease. There is conflicting evidence on the effects of testosterone therapy on body composition and metabolism.”

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Article Title: Minipuberty in Klinefelter syndrome: Current status and future directions

Authors: Aksglaede, Davis, Ross, and Juul

Date of Publication: June 2020

“Klinefelter syndrome is highly underdiagnosed and diagnosis is often delayed. With the introduction of non-invasive prenatal screening, the diagnostic pattern will require an updated description of the clinical and biochemical presentation of infants with Klinefelter syndrome. In the first months of life, the hypothalamic–pituitary–gonadal (HPG)-axis is transiently activated in healthy males during the so-called minipuberty. This period represents a “window of opportunity” for evaluation of the HPG-axis before puberty and without stimulation tests. Infants with Klinefelter syndrome present with a hormonal surge during the minipuberty. However, only a limited number of studies exist, and the results are contradictory. Further studies are needed to clarify whether infants with Klinefelter syndrome present with impaired testosterone production during the minipuberty. The aim of this review is to describe the clinical and biochemical characteristics of the neonate and infant with Klinefelter syndrome with special focus on the minipuberty and to update the clinical recommendations for Klinefelter syndrome during infancy.”

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Article Title: Psychological functioning, brain morphology, and functional neuroimaging in Klinefelter syndrome

Authors: Skakkebæk, Gravholt, Chang, Moore, and Wallentin

Date of Publication: June 2020

“Klinefelter syndrome (KS; 47,XXY) impacts neurodevelopment and is associated with an increased risk of cognitive, psychological and social impairments, although significant heterogeneity in the neurodevelopmental profile is seen. KS is characterized by a specific cognitive profile with predominantly verbal deficits, preserved function in non-verbal and visuo-spatial domains, executive dysfunction and social impairments, and by an increased vulnerability toward psychiatric disorders. The neurobiological underpinnings of the observed neuropsychological profile have not been established. A distinct pattern of both global and regional brain volumetric differences has been demonstrated in addition to preliminary findings of functional brain alterations related to auditory, motor, language and social processing. When present, the combination of cognitive, psychological and social challenges has the potential to negatively affect quality of life. This review intends to provide information and insight to the neuropsychological outcome and brain correlates of KS. Possible clinical intervention and future directions of research will be discussed.”

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