Constitutional and acquired autosomal aneuploidy.

Colleen Jackson-Cook1

  • 1Department of Pathology, Virginia Commonwealth University, Richmond, VA 23298, USA. ccook@mcvh-vcu.edu

Summary

Aneuploidy, or abnormal chromosome numbers, can be inherited or acquired. Understanding its frequency, causes, and effects is crucial for managing age-related diseases.

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Nondisjunction01:21

Nondisjunction

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate correctly and move to the opposite poles of the cells. This produces daughter cells with abnormal chromosome numbers.  Nondisjunction is common during anaphase I or anaphase II of meiosis.  Mutations in synaptonemal complex proteins that attach homologous chromosomes increase the chances of nondisjunction in anaphase I of meiosis I. In contrast, mutations in topoisomerases and condensins that hold sister...
Nondisjunction01:29

Nondisjunction

During meiosis, chromosomes occasionally separate improperly. This occurs due to failure of homologous chromosome separation during meiosis I or failed sister chromatid separation during meiosis II. In some species, notably plants, nondisjunction can result in an organism with an entire additional set of chromosomes, which is called polyploidy. In humans, nondisjunction can occur during male or female gametogenesis and the resulting gametes possess one too many or one too few chromosomes.
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Genomic Imprinting and Inheritance

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Meiosis I

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Meiosis I

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