XXXY syndrome
| XXXY syndrome | |
|---|---|
| Classification and external resources | |
| ICD-10 | Q98.1 |
| Orphanet | 96263 |
XXXY syndrome is a sex chromosome aneuploidy in which males have two extra X chromosomes. Human cells usually inherit two sex chromosomes, one from the mother and one from the father. Usually, females have two X chromosomes (XX) and males have one X and one Y chromosome (XY). The appearance of at least one Y chromosome with a properly functioning SRY gene makes a male. As a result, XXXY only affects males. Males affected with XXXY syndrome have 48 chromosomes instead of the typical 46. This is why XXXY syndrome is sometimes referred to as 48, XXXY syndrome or 48, XXXY. The symptoms of this disease is very similar to Klinefelter syndrome, including delayed or reduced male puberty and infertility. It is estimated that XXXY affects one in every 50,000 male births.
The symptoms of 48, XXXY syndrome are similar to those of Klinefelter syndrome, though usually the symptoms are more severe in 48, XXXY syndrome. Like Klinefelter syndrome, the presence of additional X chromosomes affects the male reproductive system, can cause physical abnormalities, and can affect cognitive development. There is a greater risk for congenetial malformations and more medical problems.
Males with XXXY syndrome can have testicular dysgenesis and hypergonadotrophic hypogonadism. Testicular dygenesis is a condition in which a male with 48, XXXY is born with that results in infertility as a result of incomplete or complete loss of spermatogenesis, therefore the male is unable to produce sperm or produces low levels of sperm. Hypergonadotrophic hypogonadism is a condition in which the function of the testes in males is reduced and can result in low levels of sex steroids produced like testosterone.
Males with 48, XXXY have a tall stature, which becomes more prominent in adulthood. Facial dysmorphism is common in males with 48, XXXY and can include increased distance between the eyes (hypertelorism), skin folds of the upper eyelid (epicanthal folds), up-slanting opening between the eyelids (palpebral fissures) and hooded eyelids. Other physical features include the fifth finger or "pinky" to be bent inwards towards the fourth finger (clinodactyly), short nail beds, flat feet, double jointedness (hyperextensibility) and prominent elbows with cubitus varus where the arm rests closer to the body. Musculoskeletal features may include congentical elbow dislocation and the limited ability of the feet to roll inwards while walking and upon landing.
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