Klinefelter Syndrome

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physiology

Text of Klinefelter Syndrome

Group 5Estrada, Civer Charm Jacob, Melissa Floresca, Jason Jalbuna, Elizabeth Gabayeron, Loren Javellana, Bea Joi Granadillos, Ryan Jayme, Paul Ivin Lee, Edward Hao, Carl jason

Background It describes a group of symptoms found in some men with an extra X chromosome. In 1942, Dr. Henry Klinefelter and some of his co-workers at Massachusetts General Hospital in Boston published a report about nine men with: enlarged breasts sparse facial and body hair small testes an inability to produce sperm

and it was this cluster of symptoms that became known as Klinefelter Syndrome.

What is Klinefelter Syndrome?

DefinitionKlinefelter syndrome is a chromosomal condition that affects male sexual development. Males with this condition typically have small testes that do not produce enough testosterone, which is the hormone that directs male sexual development before birth and during puberty.

What are the genetic changes related to Klinefelter syndrome?

Klinefelter syndrome is a condition related to the X chromosome and Y chromosome (the sex

chromosomes). People typically have two sex chromosomes in each cell: females have two X chromosomes (46,XX), and males have one X and one Y chromosome (46,XY).

Most often, Klinefelter syndrome results from the presence of a single extra copy of the X chromosome

in each of a male's cells (47,XXY). Extra copies of genes on the X chromosome interfere with male sexual development, preventing the testes

from functioning normally and reducing the levels oftestosterone

Klinefelter Variants XXXY 48, XXYY 48, Mild mental retardation Tall stature Gynecomastia Long, thin limbs Mild to moderate mental retardation Slow motor development Poor coordination Immature behavior Abnormal face

Small testes

Hypertelorism

Clinodactyly

49, XXXYY Moderate to severe

49, XXXXY

mental retardation

Mild to moderate mental retardation Radioulnar synostosis Hypergonadotropic

Passive but occasionally aggressive behavior

Temper tantrums Tall stature Gynecomastia Hypogonadism

hypogonadism Severely impaired language

Behavioral problems

Prevalence Klinefelter syndrome affects 1 in 500 to 1,000 males. Most variants of Klinefelter syndrome are much

rarer, occurring in 1 in 50,000 or fewer male births.

Klinefelter syndrome does not occur in females.

90% have the XXY karyotype which is caused by meiotic nondisjunction of the X chromosome during gametogenesis 10% have a mosaic karyotype caused by nondisjunction of the x chromosome during early mitosis of the zygote

Other names: Klinefelter's Syndrome 47,XXY XXY Syndrome

XXY Trisomy

Signs and Symptoms The type and degree of symptoms displayed in men with the XXY Condition depends on how many XXY

cells the man has, how much testosterone his body isproducing, and his age when the condition was diagnosed.

Late physical development as a baby is one of theearliest presentations of the condition.

As the child grows he may be taller than his peers but have less muscle control and

coordination.

In puberty he may have less facial and body hair and be broader in the hips than other boys. Enlarged breasts (gynecomastia), weaker bones and less energy are experienced in teens, and adult men with XXY are often taller than their peers.

Patients may lack secondary sexual characteristics

because of a decrease in androgen production. Thisresults in sparse facial, body, or sexual hair; a highpitched voice; and fat distribution as is observed in females.

Infertility, azoospermia, or both may result from atrophy of the seminiferous tubules.

Most men with XXY are able to enjoy a normal sex life, but 95 to 99 percent of them are infertile. In fact,

the condition is often not even discovered until aman undergoes genetic testing in order to determine the cause of his sterility.

Children with XXY may also have

trouble learning to talk, using

language to express their thoughts and needs, and processing what they hear.

These problems generally resolvethemselves as the child ages, but adult men may continue to have trouble with tasks that involve reading and writing.

Pronounced shyness, lack of self-confidence, and atendency to be more helpful and obedient than other

symptoms of XXY. children are also possible early By adulthood, XXY males look similar to males They are also more likely than other men to have certain health problems, such as autoimmune disorders (SLE), breast cancer, vein diseases, osteoporosis, and tooth decay.

without the condition, although they are often taller.

Varicose veins occur in 20-40% of patients. The prevalence of venous ulcers is 10-20 times of deep vein thrombosis and pulmonary embolism is increased. Patients may exhibit behavioral problems and psychological distress. This may be due to poor

higher than in healthy individuals, and the risk

self-esteem and psychosocial development or adecreased ability to deal with stress.

Diagnostics A karyotype is used to confirm the diagnosis. In this procedure, a small blood sample is drawn.

White blood cells are then separated fromthe sample, mixed with tissue culture medium, incubated, and checked for

chromosomal abnormalities, such as anextra X chromosome.

Treatment The genetic variation is irreversible, but its symptoms can be altered or treated in a number of ways, including testosterone treatment and other therapies. Inadequately treated hypogonadism in Klinefelter syndrome increases recognized psychosocial morbidity. Support and acceptance is strongly recommended for the patient.

Prognosis Infertility is nearly universal Physical findings are generally subtle Behavioral characteristics are highly variable On average adults have modestly reduced intelligence verbal reasoning, language skills and

motor dexterity Increased number of X chromosomes is correlated with increase phenotypic severity

Can it be inherited? it This condition is not inherited;usually occurs as a random event during the formation of reproductive cells (eggs and sperm). An error in cell division called

nondisjunction results in areproductive cell with an abnormal number of chromosomes.

For example, an egg or sperm cell may gain one

X chromosome as a or more extra copies of thereproductive cells contributes to the genetic makeup of a child, the child will have one or more extra X chromosomes in each of the

result of nondisjunction. If one of these atypical

body's cells.

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