Klinefelter syndrome

Klinefelter syndrome (KS) also known as 47,XXY or XXY, is the set of symptoms that result from two or more X chromosomes in males. The primary features are infertility and small testicles. Often, symptoms may be subtle and many people do not realize they are affected. Sometimes, symptoms are more prominent and may include weaker muscles, greater height, poor coordination, less body hair, breast growth, and less interest in sex. Often it is only at puberty that these symptoms are noticed. Intelligence is usually normal; however, reading difficulties and problems with speech are more common. Symptoms are typically more severe if three or more X chromosomes are present (48,XXXY syndrome or 49,XXXXY syndrome).Timing of diagnosis Klinefelter syndrome (KS) also known as 47,XXY or XXY, is the set of symptoms that result from two or more X chromosomes in males. The primary features are infertility and small testicles. Often, symptoms may be subtle and many people do not realize they are affected. Sometimes, symptoms are more prominent and may include weaker muscles, greater height, poor coordination, less body hair, breast growth, and less interest in sex. Often it is only at puberty that these symptoms are noticed. Intelligence is usually normal; however, reading difficulties and problems with speech are more common. Symptoms are typically more severe if three or more X chromosomes are present (48,XXXY syndrome or 49,XXXXY syndrome). Klinefelter syndrome usually occurs randomly. An older mother may have a slightly increased risk of a child with KS. The condition is not typically inherited from one's parents. The underlying mechanisms involves at least one extra X chromosome in addition to a Y chromosome such that the total chromosome number is 47 or more rather than the usual 46. KS is diagnosed by the genetic test known as a karyotype. While no cure is known, a number of treatments may help. Physical therapy, speech and language therapy, counselling, and adjustments of teaching methods may be useful. Testosterone replacement may be used in those who have significantly lower levels. Enlarged breasts may be removed by surgery. About half of affected males have a chance of fathering children with the help of assisted reproductive technology, but this is expensive and not risk free. Males appear to have a higher risk of breast cancer than typical, but still lower than that of females. People with the condition have a nearly normal life expectancy. Klinefelter syndrome is one of the most common chromosomal disorders, occurring in one to two per 1,000 live male births. It is named after the endocrinologist Harry Klinefelter, who identified the condition in the 1940s. In 1956, identification of the extra X chromosome was first noticed. Mice can also have the XXY syndrome, making them a useful research model. While XXY males can possibly be characterised based on physical characteristics, substantial variation in physical and developmental traits mean the only reliable method of positive or negative identification is karyotype testing. As babies and children, XXY males may have weaker muscles and reduced strength. As they grow older, they tend to become taller than average. They may have less muscle control and coordination than other boys of their age. During puberty, the physical traits of the syndrome become more evident; because these boys do not produce as much testosterone as other boys, they have a less muscular body, less facial and body hair, and broader hips. As teens, XXY males may develop breast tissue and also have weaker bones, and a lower energy level than other males. By adulthood, XXY males look similar to males without the condition, although they are often taller. In adults, possible characteristics vary widely and include little to no sign of affectedness, a lanky, youthful build and facial appearance, or a rounded body type with some degree of gynecomastia (increased breast tissue). Gynecomastia is present to some extent in about a third of affected individuals, a slightly higher percentage than in the XY population. About 10% of XXY males have gynecomastia noticeable enough that they may choose to have cosmetic surgery. Affected males are often infertile, or may have reduced fertility. Advanced reproductive assistance is sometimes possible.