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c/o Monash Institute of Medical Research Monash Medical Centre 246 Clayton Road, Clayton, Vic 3168 Tel: 1300 303 878 Fax: 61 3 9594 7111 Email: email@example.com Klinefelter’s Syndrome fact sheets Page 1 of 2 What is Klinefelter’s such as hair and beard growth, penile after birth (postnatally). In other growth, muscle gain, bone strength cases it is not identiﬁed until around Syndrome? and fat distribution. Testosterone the time of puberty when expected Klinefelter’s Syndrome is a genetic plays an essential role in reproductive physical changes are delayed or do condition that only affects males. and sexual function in men. not occur. However, symptoms are It is congenital, which means that not always very obvious and the the condition is present from birth. The inadequate production of diagnosis is not made until the man testosterone in men with Klinefelter’s seeks medical help for infertility or for Syndrome affects the development of What causes Klinefelter’s these male characteristics. a loss of sex drive or bone fracture. Syndrome? The extra X chromosome also affects Men with Klinefelter’s Syndrome the ability to produce sperm. Why is Klinefelter’s have an extra X chromosome. Men with this condition are infertile Syndrome under-diagnosed? Chromosomes are found in each as they have almost always no sperm It is suspected that as many as three cell of the human body. They carry in their ejaculate (azoospermia). quarters of the men with Klinefelter’s the genetic material that determines Syndrome are not diagnosed and all human characteristics, including How common is so remain untreated for life1. The hair colour, eye colour, height, and reasons for the under-diagnosis of gender. In total, each cell has 23 pairs Klinefelter’s Syndrome? this condition vary. Doctors may of chromosomes (or a total of 46). Klinefelter’s Syndrome affects not routinely check testicular size. about one in 650 men. It is one Of the 23 pairs of chromosomes, one Also, some signs and symptoms of of the most common genetic pair are sex chromosomes. These this condition during childhood and disorders. However, it is believed determine a person’s gender. One sex puberty, such as learning difﬁculties that many men with Klinefelter’s chromosome is inherited from mother and behavioural problems, can be due Syndrome are never diagnosed1. and the other from the father. Females to other medical conditions. always pass on an X chromosome, As a result, doctors may not consider but males can pass on an X or a How is Klinefelter’s Klinefelter’s Syndrome in these cases. Y chromosome. The normal male Syndrome diagnosed? A lack of knowledge about their own chromosome arrangement is 46XY, Small testes (1 – 4 ml, about the size body is another reason that men with but men with Klinefelter’s Syndrome of a sultana grape) after puberty are an undiagnosed Klinefelter’s Syndrome have 47XXY. The extra X chromosome indication of Klinefelter’s Syndrome in may not visit a doctor. These men may can come from either parent. 99% of cases. Diagnosis is conﬁrmed be unaware of how small their testes The exact reason men with using a blood test called a karyotype. are and they may not think anything this condition receive an extra This test assesses the number and is wrong. Other men may be too shy X chromosome is not known. features of the chromosomes in or embarrassed to approach a doctor if However, some researchers a sample of cells from blood. concerned about the size of their testes. believe that increased maternal age A blood test is also carried out to signiﬁcantly affects the prevalence determine levels of testosterone, What are the signs and of Klinefelter’s Syndrome1. luteinizing hormone (LH) and symptoms before puberty? follicle stimulating hormone (FSH). Klinefelter’s Syndrome is not usually What are the effects of Luteinizing hormone stimulates diagnosed in newborn boys as they the production of testosterone. Klinefelter’s Syndrome? usually appear to be normal. In many men with Klinefelter’s In young boys with the condition, Klinefelter’s Syndrome is the Syndrome, levels of LH are raised, the following problems may occur: most common cause of male but testosterone levels are borderline hypogonadism, a condition or below normal. FSH levels are • Difﬁculties with speech and reading; where men are unable to produce also raised indicating damage to the • Delayed motor development; both sperm and enough of the sperm producing tubes in the testes. • Reduced attention span; male hormone testosterone • Poor muscle tone; for the body’s needs. With the increase in prenatal testing • Behavioural problems. such as amniocentesis or chorionic Testosterone is the most important villus sampling (CVS) Klinefelter’s However, these signs and androgen in men. Androgens are Syndrome may be diagnosed before symptoms may also occur in hormones responsible for the birth, or by pediatricians immediately other medical conditions. development of male characteristics Klinefelter’s Syndrome fact sheets Page 2 of 2 Taller than How is Klinefelter’s How is infertility treated average height Syndrome treated? in men with Klinefelter’s Klinefelter’s Syndrome cannot be Syndrome? Reduced facial hair cured, but men with the condition Infertility is a major implication require life-long testosterone therapy of Klinefelter’s Syndrome. to maintain general well-being. Infertility counselling is available Reduced body hair for men coming to terms with Breast development What is testosterone childlessness and its effect on them and their partner. (gynaecomastia) therapy? Replacement of testosterone may be In some cases, sperm can be found in Osteoporosis given to men who are not producing the ejaculate of men with Klinefelter’s Feminine fat Syndrome or may be found in the high enough levels of testosterone. distribution testes by biopsy. In these cases, Small testes Testosterone therapy comes in a assisted reproductive technologies (testicular atrophy) number of forms. These include: such as Intracytoplasmic Sperm • Intramuscular injections; Injection (ICSI) can be accessed to • Skin patches; achieve pregnancy. ICSI involves • Gels applied on the skin; injecting a single sperm into the egg • Implants; by piercing the outer covering of the • Oral capsules. egg. At this time it is still unclear in what percentage of Klinefelter’s Patient convenience and familiarity, men sperm can be found. cost and availability will depend on the type of treatment prescribed. For most men who wish to have children with their partner, the A general practitioner or best option is donor insemination. endocrinologist supervises Donor insemination involves testosterone therapy in men implanting donated sperm into a with Klinefelter’s Syndrome. woman to achieve pregnancy. What are the signs and symptoms from puberty When should testosterone What other treatments onwards? therapy start in men with are available for men with The signs and symptoms of Klinefelter’s Syndrome? Klinefelter’s Syndrome during Klinefelter’s Syndrome? puberty and adulthood include: Testosterone therapy in males with Men who develop gynaecomastia Klinefelter’s Syndrome should be can have their breasts removed • Small testes; started from puberty. Teenage boys surgically (mastectomy). A plastic • Breast enlargement; with the condition should start off surgeon specialising in cosmetic • Taller than average height; on a lower dose of testosterone surgery can perform this procedure. • Fat accumulation on than adult men, and build up to the abdomen and hips; full dose as puberty progresses. • Reduced facial and body hair and References decreased shaving frequency; Management of Klinefelter’s 1 Bojesen A, Juul S, Gravholt CH Prenatal and postnatal • Reduced libido; Syndrome in teenage boys prevalence of Klinefelter Syndrome: A national registry • Poor erections; may need school involvement. study. J Clin Endocrinol Metab 88(2): 622-626 (2003). • Fatigue; For boys who have learning For more information on • Infertility; difﬁculties, they may beneﬁt from Klinefelter’s Syndrome visit: • Osteoporosis; extra assistance at school. www.genetic.org/ks/ • Depression. About the Author Andrology Australia is an initiative funded by the Australian Professor Rob McLachlan Government Department of Health and Ageing. MMBS FRACP PhD The information in this fact sheet has been provided for educational Prince Henry’s Institute of Medical Research purposes only. It is not intended to take the place of a clinical diagnosis or proper medical advice from a fully qualiﬁed health Date: June 2005 professional. Andrology Australia urges readers to seek the services of a qualiﬁed medical practitioner for any personal health concerns.