Klinefelter syndrome

What Is Klinefelter Syndrome? Klinefelter syndrome is a genetic condition in which a boy is born with an extra X chromosome. Instead of the typical XY chromosomes in men, they have XXY, so this condition is sometimes called XXY syndrome. Men with Klinefelter usually don’t know they have it until they run into problems trying to have a child. There’s no cure, but it can be treated. What Causes Klinefelter Syndrome? You get the extra X chromosome by chance. Either the egg or the Men with Klinefelter may have: • An extra X chromosome in every cell, which is the most common • An extra X chromosome in only some cells, called mosaic Klinefelter, in which you don’t have as many symptoms • More than one extra X chromosome, which is very rare and more severe Symptoms of Klinefelter Syndrome Some men show symptoms of Klinefelter as children, but others don’t know they have it until puberty or adulthood. Many men never realize that they have it because symptoms aren’t always present. Symptoms of Klinefelter vary with age and include: Babies: • Hernia • More quiet than usual • Slower to learn to sit up, crawl, and talk • Testicles that haven’t dropped into the scrotum • Weaker muscles Children: • A hard time making friends and talking about feelings • Low energy levels • Problems learning to read, write, and do math • Shyness and low confidence Teenagers: • Larger • Less facial and body • Less muscle tone, and muscles grow slower than usual • Longer arms and legs, wider hips, and a sh...

What isKlinefelter syndrome? Most men are born with a pair of XY chromosomes, while most females are born with pair of XX chromosomes. Klinefelter syndrome occurs when a male is born with an extra X chromosome. Thus a male with Klinefelter has XXY instead of the usual XY pair. Because males with this condition produce less of the male hormone testosterone than other males, they are less masculine-looking than their peers. The condition usually leads to infertility in adult life. Klinefelter has been linked to increased risk for autoimmune disorders, such as Klinefelter occurs in one out of every 500 to 1,000 newborn males. Symptoms • Delayed or incomplete sexual development during puberty • Feminine features • Underdeveloped external genitalia • Sparse or absent facial and body hair • Enlarged breasts • Learning problems Diagnosis The definitive diagnosis is karyotype testing that shows the extra X chromosome. Other tests may include: • Semen count • Blood tests to measure the levels of certain sex hormones When to Call for Help If a boy fails to mature sexually during puberty, call your health care provider. Treatment Testosterone therapycan improve many of the signs and symptoms associated with the disorder.

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Klinefelter syndrome is a common genetic condition where a male is born with an extra X chromosome. Typically, a male has one X and one Y chromosome. People with Klinefelter syndrome can experience breast growth, breast cancer, osteoporosis, infertility and learning difficulties. Treatment typically involves physical and emotional therapy, as well as hormone replacement. Overview What is Klinefelter syndrome? A typical man or person Klinefelter syndrome is a congenital condition, which means it’s present from the time of birth. There are certain tests that can be done during pregnancy that can diagnose it before birth, however more often it’s diagnosed later in life. If not found before birth, it can sometimes be diagnosed because the baby has a smaller penis than expected, or later in the teenage years if puberty doesn’t start or progress as expected. Many people AMAB may not be diagnosed at all, or only when experiencing fertility challenges later in life (if they’re having a difficult time getting pregnant with their partner). In most cases, the differences in their puberty and/or fertility are because the testicles have early “failure” and cannot make enough testosterone and/or sperm. This results in these individuals needing testosterone replacement and testing for fertility. People with Klinefelter syndrome are also more likely to develop certain conditions that are known as metabolic syndromes. These conditions include: • • • High cholesterol and fats called triglyc...