What is Klinefelter syndrome?
Klinefelter syndrome is a genetic condition that causes an extra X chromosome in people assigned male at birth. Also known as XXY syndrome, around one person in every 600 is born with this condition. Symptoms can be subtle. In fact, many people aren’t diagnosed until adulthood, and others don’t know they have it. Delayed development as a child, infertility, weaker bones, and other diseases can result from having XXY chromosomes.
Penn Medicine’s endocrinology specialists are experts at diagnosing and treating hormonal conditions like Klinefelter syndrome. We do a complete assessment to determine if you have the condition and create a treatment plan to address your symptoms. Because the syndrome can affect your bones, our experts work with bone disease specialists, including at the Penn Bone Center, to evaluate you and provide treatments to reduce your risk of fractures. Although there’s no cure, our providers bring you therapies that help you live a healthy life.
Klinefelter syndrome symptoms
The effects of Klinefelter syndrome can range from mild to more severe. Signs and symptoms might include:
- Undescended testes at birth and a small penis
- Delays in sitting, crawling, walking, or speaking, or trouble with learning
- Later than usual puberty or an incomplete puberty
- Low testosterone levels and less hair on the face and body
- An increased amount of breast tissue (gynecomastia)
- Long legs and a short torso, or a tall stature
- Reduced bone density (osteopenia or osteoporosis)
- Low sperm count or the inability to produce sperm (male infertility)
Other symptoms of Klinefelter syndrome may include:
- Bones that don’t connect correctly in an arm
- Blood clots
- Low energy
- Having Klinefelter syndrome also increases the risk of type 2 diabetes, varicose veins, autoimmune disorders like lupus and certain cancers.
Causes of Klinefelter syndrome
An extra X chromosome in your genetic code causes the syndrome. It happens randomly before birth and isn’t passed down in families. Typically, a person assigned male at birth has 46 total chromosomes, including one X and one Y. But if you have Klinefelter syndrome, you have 47 chromosomes, and your sex chromosomes are XXY. Sometimes you might have three or four X chromosomes, although this is rare.
Diagnosing and testing for Klinefelter syndrome
To diagnose Klinefelter syndrome, your doctor will do a physical exam and order blood tests to check your hormone levels and analyze your chromosomes. A blood test called a karyotype can let your doctor know if you have an additional X chromosome. Tests during pregnancy can also diagnose the syndrome in an unborn baby, but they’re usually done to check for other conditions.
Klinefelter syndrome treatment
Speech, occupational, and physical therapy can help support development during childhood, along with coordination and muscle strength. Testosterone replacement therapy can treat XXY syndrome during puberty and in adulthood. You might take testosterone as injections, a gel, or a patch. The treatment can give you a deeper voice, more muscle mass, an increased sex drive, and stronger bones. Your doctor might also recommend supplements and medications for bone health. Surgery can remove extra breast tissue. If you have infertility and want to start a family, in vitro fertilization (IVF) and assisted reproductive technologies may help.
Complete care for Klinefelter syndrome
An accurate diagnosis is the first step to getting treatments that can improve your health and reduce your risk of complications from Klinefelter syndrome. Penn Medicine’s endocrinologists, including pediatric specialists, provide expert guidance across Pennsylvania and New Jersey for all types of hormonal disorders. Our specialists also conduct research into conditions related to chromosome changes, giving us deep knowledge and insight into conditions like Klinefelter syndrome.
Because symptoms vary, our experts will create a treatment plan designed to meet your unique needs. When we treat children, we’ll monitor their testosterone levels so that hormone replacement therapy can begin at the right time. Our experts can also address infertility, extra breast tissue, and any other concerns you have. At the Penn Bone Center, we use advanced technology to test the density of your bones to give you the most effective treatments. We’re here to help improve your quality of life throughout the testing, diagnosis, and treatment processes.