Klinefelter syndrome: symptoms, diagnosis, treatment and fertility

The NHS says possible features, which are not always present, differ by age. Klinefelter syndrome does not usually cause obvious symptoms early in childhood, and even later symptoms can be hard to spot.

Chromosomes are packages of genes found in every cell. The NHS explains that a male usually has one X and one Y chromosome (XY), and in Klinefelter syndrome a boy is born with an extra copy of the X chromosome (XXY). Boys and men with it are still genetically male.

The NHS says the extra X chromosome carries extra copies of genes, which may interfere with development of the testicles so that they make less testosterone than usual. The extra genetic information may be in every cell or only some cells, known as mosaic Klinefelter syndrome.

The extra chromosome comes from either the egg or the sperm, with an equal chance of either, and the NHS says this seems to happen randomly. The NHS notes the risk of a woman having a son with Klinefelter syndrome may be slightly higher if the mother or father are older.

The NHS says to see your GP if you have concerns about your son's development or notice symptoms in yourself or your son. Early diagnosis and treatment can help prevent health problems in the future.

A GP may suspect it after a physical examination and may suggest a blood sample to check reproductive hormone levels. The diagnosis is confirmed by checking a blood sample for the extra X chromosome. The NHS adds that in many cases it is only detected when a man has fertility tests, and that it can be picked up as part of some screening tests during pregnancy.

The NHS says there is no cure, but some associated problems can be treated if necessary. It lists the possible treatments below.

Testosterone replacement therapy (TRT) involves medicines containing testosterone. The NHS says it can be taken as gels or tablets in children, or given as gel or injections in adults, and may be considered once puberty begins. It may help with development of a deep voice, facial and body hair, muscle mass, reduction in body fat and energy. The NHS says long-term TRT in adulthood may also help with osteoporosis, low mood, reduced sex drive, low self-esteem and low energy, although it cannot reverse infertility. A paediatric endocrinologist should be seen at puberty, and TRT is monitored by your care team because it can cause side effects.

• Testosterone replacement therapy.

• Speech and language therapy in childhood to help with speech development.

• Educational and behavioural support at school for any learning or behaviour difficulties.

• Occupational therapy for co-ordination problems associated with dyspraxia.

• Physiotherapy to help build muscle and strength.

• Psychological support for any mental health issues.

• Fertility treatment, such as artificial insemination using donor sperm, or intracytoplasmic sperm injection (ICSI) using sperm removed in a small operation.

• Breast reduction surgery to remove excess breast tissue.

The NHS lists inability to have children naturally as a possible feature in adulthood and says infertility tends to be the main problem. It also lists fertility treatment options: artificial insemination with donor sperm, or ICSI using sperm taken during a small operation to fertilise an egg in a laboratory.

The NHS says TRT cannot reverse infertility and may be stopped during fertility treatment, or not started until afterwards. Whether sperm can be found varies, and this is something to discuss with a specialist fertility team. For general information on infertility and fertility treatment in the UK, the NHS says treatment offered depends on the cause and what is available from your local integrated care board, and that private clinics should be licensed by the Human Fertilisation and Embryology Authority (HFEA).

The NHS says men with Klinefelter syndrome are at a slightly increased risk of some other health problems, which can usually be treated, and TRT may help reduce the risk of some of them. The risk is described as slightly increased, and many people are not significantly affected.

• Type 2 diabetes.

• Weak and fragile bones (osteoporosis).

• Cardiovascular disease and blood clots.

• Autoimmune disorders such as lupus.

• An underactive thyroid gland (hypothyroidism).

• Anxiety, learning difficulties and depression, although intelligence is usually unaffected.

• Male breast cancer, although this is very rare.

• The NHS says a healthy diet, regular exercise, stopping smoking and keeping alcohol to no more than 14 units a week, spread across 3 days, can help reduce the chances of conditions such as type 2 diabetes, osteoporosis and cardiovascular disease.

On the NHS, a GP can arrange hormone and chromosome blood tests and refer to paediatric or adult endocrinology and, where relevant, fertility services. Care for learning, speech and co-ordination usually involves school, speech and language therapy and occupational therapy services.

Private endocrinology and fertility clinics also assess and treat people with Klinefelter syndrome, usually self-paid. The NHS advises that any private fertility clinic should be licensed by the HFEA.