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 also 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 doctors can treat it.
What Causes Klinefelter Syndrome?
You get the extra X chromosome by chance. Either the egg or the sperm that came together to create you had an extra X chromosome. Older women have a slightly higher chance of having a boy with XXY syndrome, but the chance is small.
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
Klinefelter Syndrome Symptoms
Some men show symptoms of Klinefelter in childhood, 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
- Quieter than usual
- Slower to learn to sit up, crawl, and talk
- Testicles that haven’t dropped into the scrotum
- Weaker muscles
Children:
- Difficulty making friends and talking about feelings
- Low energy levels
- Problems learning to read, write, and do math
- Shyness and low confidence
Teenagers:
- Larger breasts than normal
- Less facial and body hair, and it comes in later
- Less muscle tone and muscles grow slower than usual
- Longer arms and legs, wider hips, and a shorter torso than other boys their age
- Puberty never comes, comes later, or doesn’t quite finish
- Small penis and small, firm testicles
- Taller than usual for the family
Adults:
- Infertility (can’t have children because they can’t make enough sperm)
- Low sex drive
- Low testosterone levels
- Problems getting or keeping an erection
Klinefelter Syndrome Diagnosis
To diagnose Klinefelter syndrome, your doctor will start with a physical exam and ask questions about your symptoms and general health. They’ll probably examine your chest, penis, and testicles and do a few simple tests, such as checking your reflexes.
Your doctor may then run two main tests:
- Chromosome analysis. Also called karyotype analysis, this blood test looks at your chromosomes.
- Hormone tests. These check hormone levels in your blood or urine.
Klinefelter Syndrome Treatment
It’s never too late to treat Klinefelter, but the earlier you start, the better.
One common treatment is testosterone replacement therapy. It can start at puberty and can spur typical body changes, such as facial hair and a deeper voice. It can also help with penis size and stronger muscles and bones, but it won’t affect testicle size or fertility.
Testosterone replacement therapy throughout your life can help prevent some of the long-term problems that come with Klinefelter.
Other treatments include:
- Counseling and support for mental health issues
- Fertility treatment (in some cases, using your own sperm to father a child)
- Occupational therapy and physical therapy to help with coordination and build muscles
- Plastic surgery to reduce breast size
- Speech and physical therapy for children
- Support in school to help with social skills and learning delays
If your child has Klinefelter, things that might help include:
- Playing sports and other physical activities to build muscles
- Taking part in group activities to learn social skills
Klinefelter Syndrome Complications
Many problems caused by Klinefelter are because of lower testosterone levels. You may have a slightly higher chance of:
- Autoimmune problems, such as lupus and rheumatoid arthritis, in which your immune system attacks healthy parts of your body
- Breast cancer and cancers that affect your blood, bone marrow, and lymph nodes
- Conditions with your hormone glands, such as diabetes
- Heart disease and problems with blood vessels
- Lung disease
- Mental health problems, such as anxiety and depression
- Weak bones (osteoporosis)
- Infertility and sexual problems
- Cavities and other oral problems
- Autism spectrum disorder
- Social and behavioral challenges, such as low self-esteem, trouble handling emotions, and impulsive actions
Klinefelter Syndrome Prognosis
Treatment can help boys and men with Klinefelter live happy, healthy lives. Advances in fertility treatments have made it possible for some to father children. In general, life expectancy is normal. Some research has found that life expectancy for men with the condition may be a year or two less than those without it because of other health problems linked to Klinefelter.
Living With Klinefelter Syndrome
For men with Klinefelter syndrome, here are some tips:
- Work with your doctor to manage your health and avoid issues such as osteoporosis.
- Discuss family planning options with your doctor.
- Join a support group or talk to others with Klinefelter syndrome for shared experiences and advice.
For Parents
Here are some ways that you can support your child with Klinefelter syndrome:
- Learn about Klinefelter syndrome and offer support to your child.
- Track your child’s development and seek help when needed, such as for speech delays.
- Schedule regular checkups.
- Encourage exercise to build your child's strength and motor skills.
- Promote social involvement to help them develop social skills.
- Work with teachers to make sure your child gets any needed educational support.
- Connect with other parents for advice and resources.
Takeaways
People with Klinefelter syndrome (XXY syndrome) are born with an extra X chromosome, which can affect their development. The condition may caus symptoms such as low muscle strength, less body and facial hair, and learning or social challenges. Treatments, especially when started early, can help improve symptoms. For example, testosterone therapy can support muscle growth, voice changes, and bone health. With medical support and therapy, you can lead a healthy life.
Klinefelter Syndrome FAQs
Who discovered Klinefelter syndrome?
Henry Klinefelter, an American physician, discovered Klinefelter syndrome condition in the 1940s, which was named after him.
