Mayoclinic. Mayo Foundation for Medical Education and Research, 2013. Web. 8 Jan. 2014.
Klinefelter’s Syndrome (XXY)
Definition
Klinefelter syndrome is a genetic condition that results when a boy is born with an extra copy of the X chromosome. Klinefelter syndrome is a common genetic condition affecting males.
Klinefelter syndrome adversely affects testicular growth, and this can result in smaller than normal testicles. This can lead to lower production of the sex hormone testosterone. Klinefelter syndrome may also cause reduced muscle mass, reduced body and facial hair, and enlarged breast tissue. The effects of Klinefelter syndrome vary, and not everyone with it develops these signs and symptoms.
Klinefelter syndrome often isn't diagnosed until adulthood. Most men with Klinefelter syndrome produce little or no sperm. But assisted reproductive procedures may make it possible for some men with Klinefelter syndrome to father children.
Symptoms
By Mayo Clinic Staff
Many boys with Klinefelter syndrome have few noticeable symptoms, and the condition may go undiagnosed until adulthood. For others, the condition has a noticeable effect on growth or appearance. Klinefelter syndrome may also cause speech and learning problems in some boys.
Signs and symptoms of Klinefelter syndrome vary by age and may include:
Babies
- Weak muscles
- Slow motor development — taking longer than average to sit up, crawl and walk
- Delay in speaking
- Quiet, docile personality
- Problems at birth, such as testicles that haven't descended into the scrotum
Boys and teenagers
- Taller than average stature
- Longer legs, shorter torso and broader hips compared with other boys
- Absent, delayed or incomplete puberty
- After puberty, less muscular bodies and less facial and body hair compared with other teens
- Small, firm testicles
- Small penis
- Enlarged breast tissue (gynecomastia)
- Weak bones
- Low energy levels
- Shyness
- Difficulty expressing feelings or socializing
- Problems with reading, writing, spelling or math
- Attention problems
Men
- Infertility
- Small testicles and penis
- Taller than average stature
- Weak bones
- Decreased facial and body hair
- Enlarged breast tissue
- Decreased sex drive
When to see a doctor
See a doctor to rule out Klinefelter syndrome or another health condition if you or your son has:
- Slow development during infancy or boyhood. If your son seems to be developing more slowly than other boys, see your son's doctor. Common signs and symptoms of Klinefelter syndrome include enlarged breast tissue (gynecomastia), small genitals, and small, firm testicles. Though some variation in physical and mental development is normal, it's best to check with a doctor if you have any concerns.
Delays in growth and development can be the first sign of a number of conditions that need treatment — including Klinefelter syndrome. If your son does have Klinefelter syndrome, early treatment, including speech therapy, can help prevent or minimize problems.
- Male infertility. If your partner hasn't gotten pregnant after a year of regular, unprotected sex, see a doctor. Infertility is usually caused by something other than Klinefelter syndrome, but many men aren't diagnosed with the condition until they realize they're unable to father a child.
Causes
By Mayo Clinic Staff
Klinefelter syndrome occurs as a result of a random error that causes a male to be born with an extra sex chromosome. Of the 46 human chromosomes, the two sex chromosomes determine a person's sex. In females, both sex chromosomes are X (written as XX). Males have an X and a Y sex chromosome (XY).
Most often, Klinefelter syndrome occurs because of one extra copy of the X chromosome in each cell (XXY). Extra copies of genes on the X chromosome can interfere with male sexual development and fertility.
Some males with Klinefelter syndrome have the extra X chromosome only in some of their cells (mosaic Klinefelter syndrome). Rarely, a more severe form of Klinefelter can occur if a male has more than one extra copy of the X chromosome.
Klinefelter syndrome isn't an inherited condition. Rather, the additional sex chromosome results from a random error during the formation of the egg or sperm or after conception.
Risk factors
By Mayo Clinic Staff
Klinefelter syndrome stems from a random genetic event. The risk of a child being born with Klinefelter syndrome isn't increased by anything a parent does or doesn't do. For older mothers, the risk is higher but only slightly.
Complications
By Mayo Clinic Staff
Complications of Klinefelter syndrome can include:
- Delayed puberty
- Noticeable physical features, such as sparse facial and body hair, unusually long legs and arms, lack of muscular development, and enlarged breast tissue
- Learning disabilities, attention problems or social development issues
- Infertility
- Weak bones (osteoporosis)
- Increased risk of varicose veins and other problems with blood vessels
- Increased risk of breast cancer and cancers of the blood, bone marrow or lymph nodes
- Increased risk of lung disease
- Increased risk of autoimmune disorders, such as type 1 diabetes and lupus
- Increased belly fat, which can lead to other health problems
- Problems with sexual function
A number of complications caused by Klinefelter syndrome are related to low testosterone (hypogonadism). Testosterone replacement therapy reduces the risk of certain health problems, especially when therapy is started at the beginning of puberty.
Tests and diagnosis
By Mayo Clinic Staff
As part of a physical examination, your doctor will likely examine your (or your son's) genital area and chest and may do tests to check reflexes and mental functioning.
The main tests used to diagnose Klinefelter syndrome are:
- Hormone testing. Blood or urine samples can reveal abnormal hormone levels that are a sign of Klinefelter syndrome. The doctor may take samples to be evaluated in the lab.
- Chromosome analysis. Also called karyotype analysis, this test is used to confirm a diagnosis of Klinefelter syndrome. It's usually done by taking a blood sample for laboratory examination to check the shape and number of chromosomes.
Treatments and drugs
By Mayo Clinic Staff
If you or your son is diagnosed with Klinefelter syndrome, early treatment can help minimize problems. You might work with a team of health care providers, including a doctor who specializes in diagnosing and treating disorders involving the body's glands and hormones (endocrinologist), a speech therapist, a pediatrician, a physical therapist, a genetic counselor, a reproductive medicine or infertility specialist, and a counselor or psychologist.
Although there's no way to repair the sex chromosome changes due to Klinefelter syndrome, treatments can help minimize its effects. The earlier a diagnosis is made and treatment is started, the greater the benefits. But it's never too late to get help.
Treatment for Klinefelter syndrome may include:
- Testosterone replacement therapy. Males with Klinefelter syndrome don't produce enough of the male hormone testosterone, and this can have lifelong effects. Starting at the time of the usual onset of puberty, testosterone replacement can help treat or prevent a number of problems.
Testosterone may be given as an injection or with a gel or patch on the skin.
Testosterone replacement therapy allows a boy to undergo the body changes that normally occur at puberty, such as developing a deeper voice, growing facial and body hair, and increasing muscle mass and penis size.
Testosterone therapy can also improve bone density and reduce the risk of fractures. It will not result in testicle enlargement or improve infertility.
- Breast tissue removal. In males who develop enlarged breasts (gynecomastia), excess breast tissue can be removed by a plastic surgeon, leaving a more normal-looking chest.
- Speech and physical therapy. These treatments can help boys with Klinefelter syndrome overcome problems with speech, language and muscle weakness.
- Educational support. Some boys with Klinefelter syndrome have trouble learning and can benefit from extra assistance. Talk to your child's teacher, school counselor or school nurse about what kind of support might help.
- Fertility treatment. Most men with Klinefelter syndrome are unable to father children, because no sperm are produced in the testicles. Some men with Klinefelter syndrome may have some minimal sperm production.
One option that may benefit men with minimal sperm production is a procedure called intracytoplasmic sperm injection (ICSI). During ICSI, sperm is removed from the testicle with a biopsy needle and injected directly into the egg.
Other alternatives for having children include adoption and artificial insemination with donor sperm.
- Psychological counseling. Having Klinefelter syndrome can be a challenge, especially during puberty and young adulthood. For men with the condition, coping with infertility can be difficult. A family therapist, counselor or psychologist can help you work through emotional issues.