Klinefelter’s Syndrome

Abstract

Abstract Klinefelter syndrome (KS) is a frequent genetic condition caused by the presence of an extra X chromosome with the resultant karyotype being 47,XXY. The condition is in males and results in hypergonadotropic hypogonadism, small testis, and infertility, although recent research has shown that some KS males harbour sparse amounts of spermatocytes that can be retrieved by testicular sperm extraction. Other characteristics include cognitive impairment, dyslexia, tall stature, gynaecomastia, a range of medical conditions, including the metabolic syndrome, type 2 diabetes, hyperlipidaemia, cardiovascular disease, extragonadal germ cell tumours, and breast cancer. Although the estimated prevalence of KS is 150 per 100 000 liveborn males, diagnosis poses several problems. Most KS are only diagnosed during adulthood, and only about 10% are diagnosed during childhood and adolescence. Studies from different countries indicate that only 25–50% of the expected number are ever diagnosed. Mortality and morbidity are high and the socioeconomic status is low. Medical therapy is directed towards hypogonadism and consists of testosterone replacement therapy, although no formal randomized clinical trial has been conducted in KS, and the prevention of lifestyle diseases. Comprehensive multidisciplinary care needs to be in place throughout life in order also to alleviate the neurocognitive problems encountered by many with KS and facilitate extra scholastic help and speech therapy, etc. The genetic background for KS is not thoroughly understood, but recent developments show global epigenetic and RNA expression changes that are likely tied with the phenotype.