Klinefelter Syndrome

Fact Sheet Klinefelter Syndrome

SYMPTOMS OF What is Klinefelter syndrome? KLINFELTERTaller than average SYNDROME height ChildhoodReduced facial hair Klinefelter syndrome is a genetic • Reduceddifficulties body with hair speech and (chromosomal) condition that only affects reading males. It is congenital, which means it is • Breastdelayed development motor development (gynecomastia) present from birth. Men with Klinefelter • Femininelower attention fat distribution span syndrome have an extra X chromosome. The • poor muscle tone normal male chromosome arrangement is Osteoperosis 46XY, but for men with Klinefelter syndrome • Smallbehavioural testes problems ( testicular atrophy) it is 47XXY. • undescended testes at birth Varicose(uncommon) veins How common is Klinefelter Puberty Adulthood syndrome? • small testes • gynecomastia (breast Klinefelter syndrome is the most common enlargement) chromosomal disorder in men, affecting • taller than average height about 1 in 650 men. However, many men with • fat accumulation on abdomen Klinefelter syndrome are never diagnosed. and hips • less facial and body hair/ Taller than average height decreased shaving frequency Reduced facial hair • low libido (sex drive) Reduced body hair • poor erections Breast development (gynecomastia) • fatigue Feminine fat distribution • infertility Osteoperosis • osteoporosis (thinning of the bones) Small testes ( testicular atrophy) • varicose veins Varicose veins • depression

What are chromosomes? Of the 23 pairs of chromosomes, one pair is called the sex chromosomes because Chromosomes are found in each cell in the they determine a person’s sex. The sex human body. They carry the genetic material chromosomes in a female are called XX and that determines all human characteristics, in a male are called XY. One sex chromosome including hair colour, eye colour, height and sex. is inherited from the mother and one from Each cell in the human body has 23 pairs of the father. Mothers always pass on an X chromosomes (a total of 46). chromosome, but fathers can pass on an X or a Y chromosome to their children.

1 / 3 What causes Klinefelter syndrome? A blood test is also carried out to look at levels of testosterone, luteinizing hormone (LH) and The extra X chromosome may come from the egg follicle stimulating hormone (FSH). LH is needed or sperm, or be ‘added’ early in the development of for the cells in the testes to make testosterone. the embryo. In either case it is not known why the Testosterone and FSH act together on the extra X chromosome happens. The brothers of men seminiferous tubules (sperm-producing tubes) with Klinefelter syndrome almost always have a in the testes to make sperm. In many men with normal 46XY chromosome pattern. Klinefelter syndrome, levels of LH are raised, but testosterone levels are borderline or below What are the main effects of normal. FSH levels are markedly raised as a sign Klinefelter syndrome? of damage to the seminiferous (sperm producing) tubules in the testes. Klinefelter syndrome is the most common cause of male hypogonadism, a condition where men are When is Klinefelter syndrome unable to produce sperm or enough of the male diagnosed? hormone, testosterone, for the body’s needs. With the increase in use of prenatal (before Testosterone is the most important androgen birth) testing (such as maternal blood testing in (male sex hormone) in men and it is needed early pregnancy), Klinefelter syndrome may be for normal reproductive and sexual function. diagnosed before birth. If not, a paediatrician may Testosterone is important for the physical diagnose Klinefelter syndrome immediately after changes that happen during male puberty, such as birth (postnatally). In other cases, Klinefelter development of the penis and testes, and for the syndrome is identified during childhood when features typical of adult men such as facial and learning or behavioural difficulties develop, body hair. Testosterone also acts on cells in the or around the time of puberty when expected testes to make sperm. physical changes are delayed or do not happen. Testosterone is also important for overall good Because the symptoms are not always obvious, health. It helps the growth of bones and muscles, the diagnosis of Klinefelter syndrome might not and it affects mood, libido (sex drive) and certain be made until the man seeks medical help for aspects of mental ability. infertility, a loss of sex drive or a bone fracture, or is not diagnosed at all. The low levels of testosterone in men with Klinefelter syndrome affect the development of Why is Klinefelter syndrome male characteristics. The extra X chromosome also under-diagnosed? affects the ability to produce sperm. Men with this condition are infertile as they almost always have It is suspected that as many as three quarters no sperm in their ejaculate (azoospermia). of the men with Klinefelter syndrome are not diagnosed and remain untreated for life. This could What are the symptoms of be because doctors do not routinely check testes Klinefelter syndrome? size.

Symptoms of Klinefelter syndrome vary between Some symptoms of Klinefelter syndrome during individuals and include a range of physical childhood and puberty, such as learning difficulties features, such as tall stature, breast development and behavioural problems, can be due to other (gynecomastia) and behavioural and learning conditions and so doctors may not think about difficulties. Small testes are present in almost all Klinefelter syndrome. men with Klinefelter syndrome. A lack of knowledge about their own body is How is Klinefelter syndrome another reason that men with undiagnosed Klinefelter syndrome may not visit a doctor. These diagnosed? men may be unaware of how small their testes are and they may not think anything is wrong. Other Small testes (1–4 mL, about the size of a men may be too shy or embarrassed to approach a sultana grape) after puberty are an indication of doctor if they are concerned about the size of their Klinefelter syndrome in most cases. testes. A diagnosis of Klinefelter syndrome is confirmed using a blood test called a karyotype that checks the number and structure of chromosomes in cells.

2 / 3 How is Klinefelter syndrome treated? How is infertility treated in men with Klinefelter syndrome? Klinefelter syndrome cannot be cured, but men with the condition need lifelong testosterone Infertility is a major issue for men with Klinefelter therapy to maintain general wellbeing. syndrome.

What are the main forms of testosterone therapy? It is rare for men with Klinefelter syndrome to have any sperm in their ejaculate; however, in around Testosterone therapy is available in Australia four in 10 men, sperm can be found in testicular in the form of injections, gels, creams, patches tissue. If sperm can be retrieved from testicular and tablets, and works very well for men with tissue, assisted reproductive technology such as confirmed androgen (testosterone) deficiency. intracytoplasmic sperm injection (ICSI) can be The type of treatment prescribed can depend used to achieve pregnancy. on patient convenience, familiarity and cost. Commercial testosterone products contain ICSI is a form of in vitro fertilisation (IVF) where only the natural testosterone molecule that is a single sperm is placed directly into each egg by chemically produced from plant materials. piercing the outer covering of the egg.

Will I need to see a specialist for For many men wishing to have children with their Klinefelter syndrome? partner, the best option is donor insemination. Donor insemination involves implanting donated A general practitioner or endocrinologist can sperm into a woman to achieve pregnancy. supervise testosterone therapy in men with Klinefelter syndrome. Counselling is available for men coming to terms with the diagnosis of Klinefelter syndrome and When should testosterone therapy issues such as infertility. start for Klinefelter syndrome? Visit healthymale.org.au Testosterone therapy in males with Klinefelter or speak to your doctor for more info. syndrome should be started from puberty. Teenage boys with the condition should start off on a lower dose of testosterone than adult men, and build up to the full dose as puberty progresses. Management of Klinefelter syndrome may need involvement from the school because these boys may have learning difficulties and benefit from extra assistance in the classroom.

EXPERT REVIEWER Prof Rob McLachlan AM MBBS FRACP PhD Healthy Male (Medical Director)

DATE REVIEWED: FEBRUARY 2018

The information in this fact sheet has been provided for educational purposes only. It is not intended to take the place of a clinical diagnosis or proper medical advice from a fully qualified health professional. Healthy Male urges readers to seek the services of a qualified medical practitioner for any personal health concerns.

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