Nondisjunction

In biology, nondisjunction is the failure of a chromosome to split correctly during meiosis.

Related Topics:
Biology - Failure - Chromosome - Meiosis

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This results in the production of gametes which have either more or less of the usual amount of genetic material, and is a common mechanism for trisomy or monosomy.

Related Topics:
Gamete - Trisomy - Monosomy

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Nondisjunction can occur in the meiosis I or meiosis II phases of cellular reproduction.

Related Topics:
Meiosis

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This is a cause of several medical conditions, including:

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• Down Syndrome - trisomy of chromosome 21
• Patau Syndrome - trisomy of chromosome 13
• Edward Syndrome - trisomy of chromosome 18
• Turner Syndrome - only one X chromosome present