Klinefelter Syndrome
Klinefelter syndrome is a genetic disorder affecting males. People with this syndrome are born with at least one extra X chromosome.
Chromosomes are structures in the nucleus of every cell in the body. Chromosomes contain the genetic information necessary to direct the growth and functioning of all the cells and systems of the body. A normal person has a total of 46 chromosomes in each cell, two of which are responsible for determining that individual's sex. Females have two X chromosomes; males have one X and one Y chromosome.
In Klinefelter syndrome, an error early in development results in an abnormal number and arrangement of chromosomes. Most commonly, a patient with Klinefelter syndrome will be born with 47 chromosomes in each cell. The extra chromosome is an X chromosome. Some Klinefelter patients have even more complex chromosomal errors, including the presence of 48, 49, or even 50 chromosomes, with all of the extras beings Xs.
Klinefelter syndrome is one of the most common chromosomal abnormalities. About one in every 1,000 infant boys is born with some variation of this disorder. While the cause of Klinefelter syndrome is now known, it has been noted that the disorder is seen more frequently among the children of older mothers.
The presence of more than one X chromosome in a male results in a significant delay in the onset of puberty. The genitals tend to be smaller than normal, and infertility is common. The testicles may remain in the abdomen, instead of descending into the scrotum as is normal. Body hair is decreased. Breast size is increased. Sexual drive is often below normal. Boys with Klinefelter syndrome tend to be tall and thin.
While it was once believed that boys with Klinefelter syndrome were uniformly mentally retarded, it has become clear that the disorder can exist with no such retardation. However, children with Klinefelter syndrome frequently have difficulty with language, including learning to speak, read, and write. Some children have difficulty with social skills, and are noted to be more shy, anxious, or immature than their peers. Overly aggressive behavior has also been noted.
The greater the number of X chromosomes present, the greater the disability. Boys with multiple extra X chromosomes have distinctive facial features, deformities of bony structures, more disordered development of male features, and a tendency to be more severely intellectually retarded.
Other conditions accompany Klinefelter syndrome. Due to abnormal development of male features, almost 100% of all men with Klinefelter will be sterile (unable to produce a child). Certain lung disease and rare tumors are more commonly found among patients with Klinefelter syndrome. Furthermore, because men with Klinefelter syndrome have enlarged breasts, they have nearly the same chance of developing breast cancer as do women.
Some symptoms of Klinefelter syndrome are treatable. Regular injections of the male hormone testosterone at the onset of puberty can promote strength, facial hair growth, and a more muscular physique.
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