Klinefelter’s syndrome


Associated with 47XXY chromosome abnormality, with hypogonadism, low level of androgens, altered androgen:estrogen ratio and 20-50 times greater risk of breast cancer in males.

Klinefelter syndrome

XXY syndrome.

47,XXY karyotype

Klinefelter syndrome (KS) is the set of symptoms that result from two or more X chromosomes in males.

Inherit a normal Y chromosome and multiple X chromosomes, giving persons a karyotype of XXY.

Persons with XXY  are considered male Swyer Syndrome.


SRY gene is transferred to the X chromosome instead of staying on the Y chromosome: testis development will no longer occur.

A variation of Klinefelter syndrome is when some cells in an individual have the extra X chromosome but others do not, referred to as mosaic Klinefelter syndrome. 

Prevalence 0.1-0.2%.

Affects one in 500–1000 newborn males.

Klinefelter syndrome is a chromosomal defect that occurs during gamete formation due to a non-disjunction error during cell division. 

Resulting in males having smaller testes, reducing the amount of testosterone and sperm production.

The most common chromosomal disorder among men.

Its primary feature is sterility.

Patient is most often present with infertility which is secondary to hypergonadotropic hypogonadism.

Symptoms may be subtle and many do not realize they are affected.

Large numbers of patients remain undiagnosed.

Sometimes symptoms: include weaker muscles, greater height, poor coordination, less body hair, smaller genitals, breast growth, and less interest in sex.

Arm span slightly increased.

At puberty these symptoms may be first are noticed.

Intelligence is usually normal.

Type two diabetes and neuropsychiatric diseases are X-chromosome independent complications.

Patients have a 4-5 time increased incidence of schizophrenia.

Reading difficulties and problems with speech are more common.

Up to 75% of patients have childhood learning disabilities and an estimated 2-10% experience seizures.

Seizures are usually partial epilepsy.

Symptoms are typically more severe if three or more X chromosomes are present.

Usually occurs randomly, although having an older mother might increase the risk slightly.

The condition is not inherited from one’s parents.

Complications due to the additional X chromosome include osteoporosis, hypercoagulability, and an increased risk of autoimmune disease, particularly systemic lupus erythematosus.


Klinefelter syndrome is approximately 14 fold higher in men with SLE compared with peers without SLE.


Underlying mechanism involves at least one extra X chromosome in addition to a Y chromosome.

There is a total of 47 or more chromosomes rather than usual 46.

Diagnosed by the genetic test known as a karyotype.

There is no cure.

Physical therapy, speech and language therapy, counselling, and adjustments of teaching methods may be helpful.

Testosterone replacement may be used.

About half of males affected with the help of assisted reproductive technology have a chance of having children.

Males appear to have a higher risk of breast cancer.

Associated with a nearly normal life expectancy.

One of the most common chromosomal disorders, occurring in 1:500 to 1:1000 live male births.

Associated with a higher incidence of germ cell tumors.

Associated, particularly, with mediastinum germ cell tumors.

First degree relatives have a 6-10 fold increased risk of having a germ cell tumor than the general population.







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