Metabolic and cardiovascular risk factors in Klinefelter syndrome

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.

Gonadal dysfunction and beyond: Clinical challenges in children, adolescents, and adults with 47,XXY Klinefelter syndrome

Klinefelter syndrome (KS) is the most frequent sex chromosomal aneuploidy. The karyotype 47,XXY originates from either paternal or maternal meiotic nondisjunction during gametogenesis. KS males are very likely to exhibit marked gonadal dysfunctions, presenting both in severely attenuated spermatogenesis as well as hypergonadotropic hypogonadism. In addition, neurocognitive and psychosocial impairments, as well as cardiovascular, metabolic and bone disorders are often found in KS and might explain for an increased morbidity/mortality. All conditions in KS are likely to be induced by both gene overdosage effects resulting from supernumerary X-chromosomal genes as well as testosterone deficiency. Notwithstanding, the clinical features are highly variable between KS men. Symptoms can become obvious at infancy, childhood, or adolescence. However, the majority of KS subjects is diagnosed during adulthood. KS adolescents require specific attention regarding pubertal development, in order to exploit their remaining fertility potential and allow for timely and tailored testosterone replacement. The chances for sperm retrieval might decline with age and could be hampered by testosterone replacement; therefore, cryostorage of spermatozoa is an option during adolescence, before the decompensation of endocrine and exocrine testicular functions becomes more overt. Sperm from semen or surgically retrieved, in combination with intracytoplasmic sperm injection enables KS males to become biological fathers of healthy children. The aim of this article is to present the current knowledge on KS, to guide clinical care and to highlight research needs.

Management of Klinefelter syndrome during transition

Klinefelter syndrome (KS) is the most common sex chromosomal disorder in males. Key findings in older adolescents and young men are small testes with variable hypo-androgenism, but almost universal azoospermia, most frequently in combination with a history of learning difficulties and behavior problems. Males with KS may come to medical attention through different medical presentations, given its association with several congenital malformations, and psychiatric, endocrine, and metabolic disorders. Preventive care is to be provided from diagnosis, preferentially through a multidisciplinary approach, including that from an endocrinologist, clinical psychologist or psychiatrist, neurologist, urologist, geneticist, sexologist, and a fertility team. Accurate information about the condition and assessment of associated medical conditions should be offered at diagnosis and should be followed by psychological counseling. Medical treatment during transition into adulthood is focused on fertility preservation and testosterone replacement therapy in the case of hypo-androgenism, and alleviation of current or future consequences of testicular fibrosis. However, more research is needed to determine the need for pro-active testosterone treatment in adolescence, as well as the conditions for an optimal testosterone replacement and sperm retrieval in adolescents and young men with KS. Furthermore, screening for associated diseases such as metabolic syndrome, autoimmune diseases, thyroid dysfunction, and malignancies is warranted during this period of life. The practical medical management during transition and, more specifically, the role of the endocrinologist are discussed in this article.

Serious venous thromboembolism, heterozygous factor V Leiden and prothrombin G20210A mutations in a patient with Klinefelter syndrome and type 2 diabetes

Klinefelter's syndrome (KS) is a common cause of man infertility characterized by small testes, gynecomastia and hypogonadism. Deep vein thrombosis and thomboembolic events are frequent in these patients. Hormone imbalance and co-existent mutations in the coagulation system may be the primary factors in this hypercoagulable state. The increased thromboembolic risk in hypogonadic men has been explained by hypofibrinolysis due to androgen deficiency. Regarding the association between KS and congenital and acquired thrombophilias, to date, only three cases have been. Here, we present the youngest KS case with pulmonary thromboembolism with the heterozygous mutations in factor V Leiden and prothrombin genes, as detected by further tests. He had the previous diagnosis of diabetes mellitus and body mass index was 30 kg/m(2). Our report discusses the prothrombotic state in KS patients, with other possible causes for the young presentation and the importance of necessary tests in emergency service admissions with embolism.

Increased activity of factor VIII coagulant associated with venous ulcer in a patient with Klinefelter's syndrome

Klinefelter's syndrome is the most frequent major abnormality of sexual differentiation in men with two or more X chromosomes. Recurrent venous ulcers as a result of a post-thrombotic syndrome are a well known symptom in patients with Klinefelter's syndrome. Until now the underlying pathomechanisms are not completely understood. Platelet hyperaggregability, factor V Leiden mutation and abnormalities in fibrinolysis were implicated as possible contributing factors. Here we describe the detection of an increased activity of factor VIII coagulant (factor VIII:C). This is the first case report on increased factor VIII:C activity associated with venous ulcers in a patient with Klinefelter's syndrome. Elevated factor VIII plasma levels are gradually accepted to be associated with an increased risk for venous thromboembolism. Therefore, we discuss that the examination of factor VIII:C may help in clarifying individual thromboembolic risks, especially in patients with Klinefelter's syndrome.