Klinefelter syndrome is the set of symptoms that result from two or more X chromosome in males. The primary feature is sterility.
The most common symptom is infertility. Other symptoms may include:
- Abnormal body proportions (long legs, short trunk, shoulder equal to hip size)
- Enlarged breasts (gynecomastia)
- Sexual problems
- Less than normal amount of pubic, armpit, and facial hair
- Small, firm testicles
- Small penis
- Tall height
Humans have 46 chromosomes. Chromosomes contain all of your genes and DNA, the building blocks of the body. The two sex chromosomes determine if you become a boy or a girl. Females normally have two of the same sex chromosomes, written as XX. Males normally have an X and a Y chromosome (written as XY). Klinefelter syndrome is one of a group of sex chromosome problems. It results in males who have at least one extra X chromosome. Usually, this occurs due to one extra X (written as XXY). Klinefelter syndrome is found in about 1 out of every 500 - 1,000 newborn males. Women who have pregnancies after age 35 are slightly more likely to have a boy with this syndrome than younger women.
About 10% of Klinefelter cases are found by prenatal diagnosis. The first clinical features may appear in early childhood or, more frequently, during puberty, such as lack of secondary sexual characters and aspermatogenesis, while tall stature as a symptom can be hard to diagnose during puberty. Despite the presence of small testes, only a quarter of the affected males are recognized as having Klinefelter syndrome at puberty and 25% received their diagnosis in late adulthood: about 64% affected individuals are not recognized as such. Often the diagnosis is made accidentally as a result of examinations and medical visits for reasons not linked to the condition.
The standard diagnostic method is the analysis of the chromosomes' karyotype on lymphocytes. In the past, the observation of the Barr body was common practice as well. To confirm mosaicism, it is also possible to analyze the karyotype using dermal fibroblasts or testicular tissue.
Other methods may be: research of high serum levels of gonadotropins (follicle-stimulating hormone and luteinizing hormone), presence of azoospermia, determination of the sex chromatin, and prenatally via chorionic villus sampling or amniocentesis. A 2002 literature review of elective abortion rates found that approximately 58% of pregnancies in the United States with a diagnosis of Klinefelter syndrome were terminated
Children with XXY differ little from other children. Although they can face problems during adolescence, often emotional and behavioral, and difficulties at school, most of them can achieve full independence from their families in adulthood. Most can lead a normal, healthy life.
The results of a study carried out on 87 Australian adults with the syndrome shows that those who have had a diagnosis and appropriate treatment from a very young age had a significant benefit with respect to those who had been diagnosed in adulthood.
There is research suggesting Klinefelter syndrome substantially decreases life expectancy among affected individuals, though the evidence is not definitive. A 1985 publication identified a greater mortality mainly due to diseases of the aortic valve, development of tumors and possible subarachnoid hemorrhages, reducing life expectancy by about 5 years. Later studies have reduced this estimated reduction to an average of 2.1 years. These results are still questioned data, are not absolute, and will need further testing.
The genetic variation is irreversible, however, individuals who want to look more masculine can take testosterone. Adolescent treated with implants of controlled release testosterone, has shown good results when appropriately monitored. Hormone therapy is also useful in preventing the onset of osteoporosis.
Often individuals that have noticeable breast tissue or hypogonadism experience depression and/or social anxiety because they are outside of social norms. This is academically referred to as psychosocial morbidity. At least one study indicates that planned and timed support should be provided for young men with Klinefelter syndrome to ameliorate current poor psychosocial outcomes. The surgical removal of the breasts may be considered for both the psychological reasons and to reduce the risk of breast cancer.
The use of behavioral therapy can mitigate any language disorders, difficulties at school and socialization. An approach by occupational therapy is useful in children with Down syndrome who have dyspraxia motor.