Klinefelter Syndrome

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Introduction

Klinefelter syndrome is a genetic condition affecting males, and it often isn't diagnosed until adulthood, results when a boy is born with an extra copy of the X chromosome.

Klinefelter syndrome may adversely affect testicular growth, resulting in smaller than normal testicles, which can lead to lower production of testosterone. The syndrome may also cause reduced muscle mass, reduced body and facial hair, and enlarged breast tissue. The effects of Klinefelter syndrome vary, and not everyone has the same signs and symptoms.

Most men with Klinefelter syndrome produce little or no sperm, but assisted reproductive procedures may make it possible for some men with Klinefelter syndrome to father children.

Causes

Klinefelter syndrome occurs as a result of a random error that causes a male to be born with an extra sex chromosome. It isn't an inherited condition.

Most often, Klinefelter syndrome is caused by a single extra copy of the X chromosome, resulting in a total of 47 chromosomes per cell. Males normally have one X chromosome and one Y chromosome in each cell (46, XY), while females have two X chromosomes (46, XX).

- An error in cell division called nondisjunction results in a reproductive cell with an abnormal number of chromosomes. For example, an egg or sperm cell may gain one or more extra copies of the X chromosome as a result of nondisjunction. If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have one extra copy of the X chromosome in each cell (XXY), the most common cause, or more extra X chromosomes in each of the body's cells which is rare and known as "variants of Klinefelter syndrome(48,XXXY, 48,XXYY and 49,XXXXY) and results in a severe form .

- People with Klinefelter syndrome usually have two X chromosomes and one Y chromosome (47, XXY). Some people with Klinefelter syndrome have the extra X chromosome in only some of their cells; these people are said to have mosaic Klinefelter syndrome, with fewer symptoms.

It is estimated that about half of the time, the cell division error occurs during development of the sperm, while the remainder are due to errors in egg development. Women who have pregnancies after age 35 have a slightly increased chance of having offspring with this syndrome.

Incidence

It is estimated that 1 in every 500 to 1,000 newborn males has an extra X chromosome, making Klinefelter syndrome one of the most common chromosomal disorders seen among newborns. Variants of Klinefelter syndrome (such as 48,XXXY, 49,XXXXY) are much rarer, occurring in 1 in 50,000 to 1 in 85,000 or fewer newborns.

Other Medical or Scientific Names

-   47,XXY 
-   XXY syndrome or condition
-   XXY trisomy
-   47,XXY/46,XY or mosaic syndrome (rare variation)
-   Poly-X Klinefelter syndrome, including the following rare variations: 
      * 48,XXYY (or tetrasomy)
      * 48,XXXY (or tetrasomy)
       *49,XXXXY (or pentasomy)

Signs and Symptoms

The signs and symptoms vary among affected people. Some men with KS have no symptoms of the condition or are only mildy affected. In these cases, they may not even know that they are affected by KS. When present. Whether or not a male with KS has visible symptoms depends on many factors, including how much testosterone his body makes, if he is mosaic (with both XY and XXY cells), and his age when the condition is diagnosed and treated. Symptoms may include:

-Small, firm testicles that produce a reduced amount of testosterone (primary testicular insufficiency). -Delayed or incomplete puberty due to the shortage of testosterone with lack of secondary sexual characteristics resulting in sparse facial, body, or sexual hair a high-pitched voice and body fat distribution resulting in a rounder, lower half of the body, with more fat deposited in the hips, buttocks and thigh instead of around the chest and abdomen. -Breast enlargement (gynecomastia). -Reduced facial and body hair. -Infertility due to low sperm count. -Tall stature. -Abnormal body proportions (long legs, short trunk, shoulder equal to hip size). -Learning disablity. -Speech delay. -Crypthochirdism (undescended testes). -Opening (meatus) of the urethra (the tube that carries urine and sperm through the penis to the outside) on the underside of the penis (hypospadias) instead of the tip of the head of the penis. -Social problems as anxiety, depression and impaired social skills. -Intellectual disability. -Distinctive facial features. -Reduced muscle mass and osteoprosis. -Poor coordination. -Severe speech difficulties. -Behavioral problems such as emotional immaturity and impulsivity and limited problem-solving skills (executive functioning). -Heart defects. -Metabolic syndrome (Nearly half of all men with Klinefelter syndrome). -Teeth problems.. -Other differences can include abnormal fusion of certain bones in the forearm (radioulnar synostosis), curved pinky fingers (fifth finger clinodactyly), and flat feet (pes planus). -Many anomalies related mostly to the skeletal system, such as cubitus varus, pigeon chest or iliofemoral articulation degeneration.

-Autism spectrum disorder (10 percent of boys and men with Klinefelter syndrome).

-Slightly increased risk of developing breast cancer(if gynecomastia develops), a rare extragonadal germ cell tumor, lung disease, varicose veins and osteoporosis as well as some autoimmune disorders such as systemic lupus erythematosus, rheumatoid arthritis and Sjogren's syndrome. -Increased risk of developing involuntary trembling (tremors) .

Diagnostic Procedures

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Outcome Measures

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Management / Interventions

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Differential Diagnosis

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Resources

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References

Myśliwiec, Andrzej & Knapik, Henryk & Pasek, Angelika & Kuszewski, Michał & Saulicz, Mariola & Ryngier, Paweł & Wolny, Tomasz. (2011). REHABILITATION OF PATIENTS WITH THE KLINEFELTER’S SYNDROME - REVIEW OF AVAILABLE LITERATURE.

https://rarediseases.info.nih.gov/diseases/8705/klinefelter-syndrome#ref_846

https://www.nichd.nih.gov/health/topics/klinefelter

https://www.ncbi.nlm.nih.gov/gtr/conditions/C0022735/?_ga=2.249310535.1187197716.1601932924-37510577.1601932924

https://www.youtube.com/watch?v=R-jqm7KXd0s&has_verified=1