Klinefelter’s Syndrome is a condition that occurs in men who have an extra X chromosome. The syndrome can affect different stages of physical, language, and social development.
Most males have one Y and one X chromosome. Having extra X chromosomes can cause a male to have some physical traits unusual for males.
Many men with an extra X chromosome are not aware that they have it, and they lead normal lives.
How common is Klinefelter’s syndrome?
Klinefelter’s syndrome is the most common chromosomal disorder in men, affecting about 1 in 650 men. However, many men with Klinefelter’s syndrome are never diagnosed.
Signs and symptoms of Klinefelter syndrome vary widely among males with the disorder. Many boys with Klinefelter syndrome have few noticeable signs, and the condition may go undiagnosed until adulthood. For others, the condition has a noticeable effect on growth or appearance.
Signs and symptoms of Klinefelter syndrome also vary by age.
Signs and symptoms may include:
- 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
Signs and symptoms may include:
- Taller than average stature
- Longer legs, shorter torso and broader hips compared with other boys
- Absent, delayed or incomplete puberty
- After puberty, less muscle and less facial and body hair compared with other teens
- Small, firm testicles
- Small penis
- Enlarged breast tissue (gynecomastia)
- Weak bones
- Low energy levels
- Tendency to be shy and sensitive
- Difficulty expressing thoughts and feelings or socializing
- Problems with reading, writing, spelling or math
- Low sperm count or no sperm
- Small testicles and penis
- Low sex drive
- Taller than average height
- Weak bones
- Decreased facial and body hair
- Less muscular than normal
- Enlarged breast tissue
- Increased belly fat
When to see a doctor
See a doctor if you or your son has:
- Slow development during infancy or boyhood
Delays in growth and development can be the first sign of a number of conditions that need treatment — including Klinefelter syndrome. Though some variation in physical and mental development is normal, it’s best to check with a doctor if you have any concerns.
- Male infertility
Many men with Klinefelter syndrome aren’t diagnosed with infertility until they realize they’re unable to father a child.
The presence of an extra X chromosome in males most often occurs when the genetic material in the egg splits unevenly. But it can also occur when the genetic material in the sperm splits unevenly. Even though Klinefelter syndrome is a genetic disorder, 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.
Testing for Klinefelter syndrome
See your GP if you have concerns about your son’s development or you notice any troubling symptoms of Klinefelter syndrome in yourself or your son.
Klinefelter syndrome isn’t necessarily anything serious, but treatment can help reduce some of the symptoms if necessary.
In many cases, it’s only detected if a man with the condition undergoes fertility tests.
Your GP may suspect Klinefelter syndrome after a physical examination and they may suggest sending off a sample of blood to check reproductive hormone levels.
The diagnosis can be confirmed by checking a sample of blood for the presence of the extra X chromosome.
There’s no cure for Klinefelter syndrome, but some of the problems associated with the condition can be treated if necessary.
Possible treatments include:
- testosterone replacement therapy (see below)
- speech and language therapy during childhood to help with speech development
- educational and behavioral support at school to help with any learning difficulties or behavior problems
- occupational therapy to help with any co-ordination problems associated with dyspraxia
- physiotherapy to help build muscle and increase strength
- psychological support for any mental health issues
- fertility treatment – options include artificial insemination using donor sperm or possibly intra-cytoplasmic sperm injection (ICSI), where sperm removed during a small operation are used to fertilize an egg in a laboratory
- breast reduction surgery to remove excess breast tissue
Testosterone replacement therapy
TRT involves taking medication containing testosterone. It can be taken in the form of gels or tablets in teenagers, or given as gel or injections in adult men.
TRT may be considered once puberty begins and may help with the development of a deep voice, facial and body hair, an increase in muscle mass, reduction in body fat, and improvement in energy. You should see a specialist in children’s hormones (a pediatric endocrinologist) at this time.
Long-term treatment during adulthood may also help with several other problems associated with Klinefelter syndrome – including osteoporosis, low mood, reduced sex drive, low self-esteem and low energy levels – although it can’t reverse infertility.
Klinefelter syndrome stems from a random genetic event. The risk of Klinefelter syndrome isn’t increased by anything a parent does or doesn’t do. For older mothers, the risk is higher but only slightly.
Klinefelter syndrome may increase the risk of:
- Anxiety and depression
- Infertility and problems with sexual function
- Weak bones (osteoporosis)
- Heart and blood vessel disease
- Breast cancer and certain other cancers
- Lung disease
- Endocrine conditions such as diabetes and hypothyroidism
- Autoimmune disorders such as lupus and rheumatoid arthritis
- Tooth problems that make dental cavities more likely
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.