Klinefelter's syndrome causes: Difference between revisions
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[[Image:XXY syndrome.svg.png|250px|thumb|left|XXY syndrome]] | [[Image:XXY syndrome.svg.png|250px|thumb|left|XXY syndrome]] | ||
The extra X chromosome is retained because of a [[Meiosis#Nondisjunction|nondisjunction]] event during [[meiosis]] (sex | The extra X chromosome is retained because of a [[Meiosis#Nondisjunction|nondisjunction]] event during [[meiosis I]] (gametogenesis). Nondisjunction occurs when homologous chromosomes, in this case the X and Y sex chromosomes, fail to separate, producing a sperm with an X and a Y chromosome. Fertilizing a normal (X) egg produces an XXY offspring. | ||
The XXY chromosome arrangement is one of the most common genetic variations from the XY [[karyotype]], occurring in about 1 in 500 live male births.<ref name="nihhd2007" /> | |||
Another mechanism for retaining the extra X chromosome is through a nondisjunction event during [[meiosis II]] in the female. Nondisjunction will occur when sister chromatids on the sex chromosome, in this case an X and an X, fail to separate. An XX egg is produced which, when fertilized with a Y sperm, yields XXY offspring. | |||
==References== | ==References== | ||
Revision as of 16:14, 14 August 2012
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Klinefelter's syndrome Microchapters |
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Klinefelter's syndrome causes On the Web |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
The extra X chromosome is retained because of a nondisjunction event during meiosis I (gametogenesis). Nondisjunction occurs when homologous chromosomes, in this case the X and Y sex chromosomes, fail to separate, producing a sperm with an X and a Y chromosome. Fertilizing a normal (X) egg produces an XXY offspring. The XXY chromosome arrangement is one of the most common genetic variations from the XY karyotype, occurring in about 1 in 500 live male births.[1]
Another mechanism for retaining the extra X chromosome is through a nondisjunction event during meiosis II in the female. Nondisjunction will occur when sister chromatids on the sex chromosome, in this case an X and an X, fail to separate. An XX egg is produced which, when fertilized with a Y sperm, yields XXY offspring.