Klinefelter syndrome is a genetic disorder that affects the development of the testes and, as a result, testosterone production. It is also known as XXY syndrome and was previously sometimes called XXY trisomy.
The most common symptom of Klinefelter syndrome (KS) in adult males is infertility. KS is also sometimes associated with language processing problems and learning disabilities. In this article, we look at the causes, symptoms, diagnosis, and treatment of KS.
Typically, females have two X chromosomes, and males have one X and one Y chromosome.
KS occurs when a male child is born with at least one extra X chromosome. This imbalance happens due to an error during egg or sperm development and results in a male having an extra X chromosome in all of his body’s cells. KS is also called XXY syndrome.
Although KS is a genetic disorder, the inclusion of the extra X chromosome is a random genetic event and is not directly inherited. KS is found in about 1 in 500 to 1,000 newborn males.
Current knowledge of KS symptoms comes from people who need treatment, and they usually have the most severe symptoms. However, a relatively small number of people have KS, which is one of the reasons why diagnosis of the disorder is sometimes missed.
Small testes are the main sign of KS and are present in all cases. Symptoms do not all occur at the same time but at different times during the lifetime of the person with KS. Symptoms appear to worsen over time.
Boys with KS tend to be quiet, sensitive, and unassertive. When they get older, they may be taller than other boys and have more belly fat than their peers.
People with KS might be slow to learn to talk, read, and write, and they might have difficulty processing what they hear.
Also, males with KS may have:
- low testosterone levels
- low sex drive
- breast development (gynecomastia)
- reduced muscle mass
- broad hips
- reduced body hair
Although infertility is the most common outcome of KS, males can also be at greater risk of developing the following complications:
Only a genetic test can conclusively diagnose KS. The test is called a karyotype. A small skin or blood sample is sent to a laboratory to find out if there is an extra X chromosome.
Learning difficulties may be the first indication that a child has KS. In adult males, infertility is often the first sign that KS may be present.
Once puberty has started, a physical examination of the chest and testes can reveal the physical symptoms of KS, such as small testes and enlarged breasts.
Further investigation may include a sperm count for reduced fertility and a hormone test for reduced testosterone.
KS may be severely under-diagnosed because doctors overlook some of its symptoms, which are similar to the symptoms of other disorders.
Only 10 percent of cases are diagnosed in childhood, and it is thought that only about 25 percent of all males with KS are ever diagnosed. On average, males with KS are not diagnosed until their mid-30s.
Chromosomal abnormalities due to KS cannot be corrected, and there is no cure. However, treatment can be effective in reducing symptoms.
While early diagnosis will help manage some of the chronic aspects of KS, it is never too late to start treatment for KS. Treatment can bring benefits at any age and may include the following:
Testosterone replacement therapy
Treatment is usually in the form of an injection, pills, gel, or a patch. Testosterone replacement therapy improves, strength, body hair growth, energy, and concentration.
Starting treatment early, usually at the onset of puberty, can prevent the long-term effects of reduced testosterone production.
Testosterone therapy does not improve testicle size or fertility.
Between 95 and 99 percent of males with KS are infertile because they do not produce enough sperm to fertilize an egg. However, more than 50 percent of males with KS do have sperm.
For men with minimal sperm production, an intracytoplasmic sperm injection (ICSI) can be effective. During an ICSI, sperm is removed from the testicle and injected directly into the egg.
If diagnosed early enough, semen or testicular tissue can be preserved before the testicular damage starts, probably at puberty. This method is called cryopreservation, and it uses very low temperatures to preserve living cells and tissues for later use.
Breast reduction surgery
There is no approved drug treatment for overdeveloped breast tissue in males. Removal of the breast tissue by a plastic surgeon is effective but comes with the risks associated with any surgery.
The result of breast reduction surgery is a chest that appears typically more masculine. It reduces the chances of developing breast cancer and can help alleviate the social stress associated with enlarged breasts in males.
Dealing with the symptoms of KS can be embarrassing and challenging for males, especially during puberty and early adulthood.
Coping with infertility can also be difficult, and a counselor or psychologist can help people to process and reduce emotional issues associated with KS.
The right support at the right time can help prevent difficulties with language, schooling, and social interaction. Additional therapeutic support may include:
- speech and physical therapy
- educational evaluation and support
- occupational therapy
- behavioral therapy
Most people with KS will live a normal, productive life. Symptoms can be mild enough to go unnoticed.
In cases where symptoms are clear and sometimes distressing, the right treatment at the right time can go a long way towards reducing or even preventing the effects of KS.
More work is needed to improve the rate of diagnosis and to provide better evidence for the timing and application of testosterone replacement therapy.
Treatment of KS can also benefit from the input of healthcare providers with different areas of expertise. Ideally, treatment will include pediatricians, speech therapists, general practitioners, psychologists, infertility specialists, urologists, and endocrinologists.
Researchers at Columbia University Medical Center in New York, NY, are currently developing a new assessment tool to help doctors spot the physical traits of KS and to start treatment early.