Klinefelter syndrome [KS] is a genetic chromosomal condition that affects only men. It causes changes to their cognitive and physical development. Although the specific symptoms of this syndrome are unique to each man who has it, the most common side effect of this condition is a lower level of testosterone production. This means that men with Klinefelter syndrome may have a delayed puberty, and incomplete puberty, and reduced levels of body hair.
Statistics on Klinefelter Syndrome
1. Klinefelter syndrome may affect up to 1 in 500 male births in the world today.
2. A recent Danish study indicated that Klinfelter syndrome was present in 153 per 100,000 babies tested.
3. An estimated 53-55% of conceptions affected with Klinefelter syndrome are expected to survive to term.
4. KS was first described in 1942 as an endocrine disorder.
5. Approximately 5% of Klinefelter syndrome cases detected at amniocentesis resulted in fetal deaths, which is similar to other disorders that are not chromosomal in nature.
6. Approximately 80% of Klinefelter cases possess the 47XXY karyotype.
7. The residual 20% of cases have higher-grade chromosome aneupolidies [48XXYY] or mosaicism [46XY/47XXY].
8. Individuals with mosaic-type Klinfelter syndrome have less severe symptoms than others with this disorder.
9. Variants of Klinefelter syndrome that include multiple X chromosomes being passed along are much rarer, occurring in just 1 in 50,000 births.
10. Klinefelter syndrome is not an inherited disorder. It can occur from sperm or egg development or occurs as a random division.
11. Men with this disorder have a higher risk than men in the general population for the development of breast cancer.
12. 10%. That’s the number of boys who have this disorder and also have a diagnosis that places them on the autism spectrum.
13. There is generally less than a 1% chance for other children in the family to be diagnosed with Klinefelter syndrome is one child has it already.
14. In many cases, there are no signs or features during pregnancy that indicate a developing baby has Klinefelter syndrome.
15. There is a slightly increased risk for boys with Klinefelter syndrome to also be born with a mild birth defect.
16. By the age of 8, children with Klinefelter are, on average, taller than 60% of children their same age.
17. Men with this disorder also tend to have longer legs, more narrow shoulders, wider hips, and a longer arm span when compared to men with the normal number of chromosomes.
18. Life expectancy for people with Klinefelter syndrome is normal.
19. The percentage of cases of Klinefelter syndrome that are believed to be undiagnosed right now: 50%.
20. Some men with an extra X chromosome have fathered healthy offspring, sometimes with the help of infertility specialists.
21. Women who have pregnancies after age 35 have a slightly increased chance of having a boy with this syndrome.
22. About half of the time the error which causes this syndrome occurs in the formation of sperm, while the remainder are due to errors in egg development.
23. A rare tumor called extragonadal germ cell tumor, lung disease, varicose veins, and osteoporosis are all at a higher risk for men with KS than for those in the general population.
24. The most common form of treatment for this disorder is testosterone therapy as it promotes strength, the development of muscles, and the growth of body hair.
25. Boys with KS may have an IQ that may be 10-15 points lower than average with verbal IQ less than performance IQ.
Causes and Symptoms
Some men with this syndrome are physically unable to have children. Because testosterone levels are low, an enlargement of the breasts may also be present. Although there may be delays or incomplete transitions from childhood into adulthood, what is unique about this syndrome is that people with it tend to be taller than their peers. There may also be delayed speech recognition, learning difficulties, and problems with language development.
Men who have Klinefelter syndrome tend to be quiet and sensitive people. They are typically not very assertive, but as with any condition, their personality characteristics can vary widely across the population spectrum. Symptoms can be very mild with this disorder, so it is believed that this syndrome is under-diagnosed in the world today. It happens because a man will receive two female X chromosomes instead of one and this interferes with their development.
There are also variants of Klinefelter syndrome that have more than just one addition female X chromose. Some men have been found to have 4 X chromosomes instead of just the one. Each additional X chromosome causes additional signs and symptoms that impact development. By knowing the statistics about this condition, parents and boys can know what to expect as they grow older.
Treatment and Prevention
There is no doubt that severe cases of Klinefelter syndrome can have a dramatic impact on boys today. Not only can it be a potential contributor to autism or an autism spectrum disorder, but it can impact learning, social development, and a number of other growth factors.
Boys with this condition may be quiet and sensitive, but that is not always the case. Some boys may choose to be loud and aggressive because they see themselves as bigger than most of the other boys in their class. In early childhood, this may even make it appear that a child is hitting all of their developmental milestones with ease. As boys with KS get older, however, a drop off is seen in intellect and physical development.
Early diagnosis, couple with effective medication management and strong social supports, are found to be the greatest supports of an individual to be able to optimize their full potential as they approach adulthood. There will always be some unique challenges that men who have Klinefelter syndrome will face. With the right therapy and enough educational support, men with this condition or even one of its rare variants can hold down a job, have a family, and live a long, fulfilling life.