Other Free Encyclopedias » Social Issues Reference » Child Development Reference - Vol 5

Klinefelter'S Syndrome

cell chromosome reduced genotype

Klinefelter's syndrome (genotype 47, XXY) is a chromosomal anomaly in which affected males have an extra X chromosome. It occurs in 1:1,000 to 1:2,000 newborn males and has been detected in .003 percent of spontaneous abortions. This condition generally arises from failure of chromosomes to separate properly during meiosis. Specifically, an egg cell bearing an additional X chromosome (or a sperm bearing both an X and a Y chromosome) unites with a normal sex cell. Approximately one-third of affected individuals show multiple Xs (48, XXXY or 49, XXXXY) or both normal and abnormal cell lines (46, XY/47, XXY).

Klinefelter's syndrome is generally not apparent until puberty, at which time secondary sexual development does not proceed. Clinical features include small testes, tall stature, breast development, reduced hormonal levels, and sterility. Mosaics, or individuals with mixed cell lines, may be fertile. Behavioral features include depressed verbal intelligence, reduced activity, increased stress, and feelings of reduced masculinity. Families may be advised to seek hormonal therapy and counseling for these children.

Bibliography

"Klinefelter Syndrome." In the On-line Medical Dictionary, 1995-1998. Available from http://www.graylab.ac.uk/omd/index.html; INTERNET.

Plomin, Robert, John DeFries, Gerald McClearn, and Peter Mc-Guffin. Behavioral Genetics, 4th edition. New York: Worth Publishers, 2001.

Nancy L. Segal

Lawrence Kohlberg (1927-1987) [next] [back] William Kessen (1925-1999)

User Comments

Your email address will be altered so spam harvesting bots can't read it easily.
Hide my email completely instead?

Cancel or

Vote down Vote up

over 3 years ago

Thank you for the sensible critique. Me & my neighbor were just preparing to do a little research on this. We got a grab a book from our area library but I think I learned more clear from this post. I am very glad to see such wonderful info being shared freely out there.
http://mitra-seo.blogspot.com/