Conditions Basics

What is Klinefelter syndrome?

Klinefelter syndrome is a genetic condition that affects males. Klinefelter syndrome occurs when someone is born with one or more extra X chromosomes. Most males have one Y and one X chromosome. Having extra X chromosomes can cause someone to have a variety of physical traits.

Many people with an extra X chromosome are not aware that they have it, and they lead normal lives. Klinefelter syndrome occurs in about 1 out of 1,000 males.

What causes it?

The presence of an extra X chromosome in males most often occurs when the genetic material that forms the egg or sperm splits unevenly. Even though Klinefelter syndrome is a genetic condition, it is not passed down through families. So parents who have a child with Klinefelter syndrome are not any more likely than other couples to have another child with the condition.

What are the symptoms?

Many people who have Klinefelter syndrome do not have obvious symptoms. Others have sparse body hair, enlarged breasts, and wide hips. The testicles almost always remain small. Sometimes the penis does not reach adult size. A person's voice may not be as deep. People usually have infertility. But they can have a normal sex life.

Some children with Klinefelter syndrome have language and learning problems.

How is it diagnosed?

Klinefelter syndrome usually is not diagnosed until the time of puberty. At this point, the child's testicles fail to grow, and you may start to notice other symptoms.

To find out if your child has Klinefelter syndrome, your doctor will ask questions about your child's past health, do a physical exam, and order tests, such as a hormone test and chromosome analysis.

In adults, other tests may be done, such as semen analysis.

Sometimes Klinefelter syndrome is found before a baby is born (prenatally). Genetic tests on cells collected from amniocentesis or chorionic villus sampling (CVS) can show when a baby has Klinefelter syndrome. So the condition may be found during pregnancy when genetic tests are done for another reason.

How is Klinefelter syndrome treated?

People with Klinefelter syndrome can be given testosterone, a hormone needed for sexual development. If treatment is started around the age of puberty, it can help adolescents with the sexual development of their bodies.

Testosterone is given by injection or through a skin patch or gel. The treatment usually continues throughout a person's life but does not help infertility.

Speech therapy and educational support can help children who have language or learning problems.

How can you help your child?

If your child has been diagnosed with Klinefelter syndrome:

• Recognize your feelings. It is natural for parents to feel that they have done something to cause Klinefelter syndrome. But this condition is beyond anyone's control. Allow yourself time to deal with your feelings, and talk with your child's doctor about your concerns.
• Educate yourself about the condition. Educating yourself will help you learn how to help your child.
• Support your child. Provide education about Klinefelter syndrome that is appropriate for their age and give them the emotional support and encouragement they need. Remind them that most people who have Klinefelter syndrome go through life with few problems.
• Be actively involved in your child's care. Talk with your doctor about the treatment. If counseling for behavioral problems is needed, or if your child has difficulty reading or has poor verbal skills, get help from qualified professionals who have experience working with children who have Klinefelter syndrome.
• Encourage your child to take part in activities to improve physical motor skills, such as karate, soccer, basketball, baseball, or swimming.
• Work with your child's teachers, principal, and school administrators.
  • Contact teachers on a regular basis to compare how your child is doing at home and at school.
  • When appropriate, let your child be present for talks with teachers. Use brief notes, telephone calls, and meetings to identify and solve problems.
  • Provide articles and pamphlets about Klinefelter syndrome to your child's teachers and school principal.
• Encourage your child's independence. Although it is important to be supportive, realize that watching over your child too much can send the message that you think they are not able to do things on their own.