Related Terms

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Background

• Polyploidy is a genetic condition in which a cell has one or more extra sets of chromosomes. Nearly every cell in the body contains a nucleus, which contains two sets of chromosomes. These chromosomes contain DNA (deoxyribonucleic acid), the building blocks of life. Each parent provides one set of 23 chromosomes to his or her offspring. Therefore, each person has 23 pairs of chromosomes. The X and Y chromosome are called sex-determining chromosomes because they distinguish males from females. Human females have a pair of X chromosomes, while males have one X and one Y chromosome.
• Aneuploidy refers to an abnormal number of chromosomes. Aneuploidy in certain chromosomes, such as trisomy 16 (three copies of chromosome 16), prevents survival of the developing fetus.
• Polyploidy occurs frequently in some organisms, such as goldfish, salmon, salamanders, and some plants, typically resulting in survival of these organisms. For example, different kinds of wheat exist because some have two sets of chromosomes, some have four sets, and others have six sets. Polyploidy may, in fact, result in the creation of a new species, as in the case of the plant salsify, in which two new tetraploid species of this plant developed from combinations of the original three species.
• Although polyploidy is fairly common in these and other "lower" organisms, polyploidy is rare in humans. Some instances of polyploidy do exist in humans, particularly in some tissues, such as the liver, and in some cancers. Polyploidy in the liver indicates growth and can be observed when part of the liver is removed; polyploidy is increased when the cells begin to grow. Triploidy is a condition in which there are three complete sets of chromosomes in a single cell; in humans, this would be 69 sets of chromosomes per cell. Tetraploidy is a condition in which there are four complete sets of chromosomes in a single cell; in humans, this would be 92 sets of chromosomes per cell. A great majority of pregnancies in which the fetus has triploidy or tetraploidy end in miscarriage, or if the pregnancy goes to full term, will result in the infant's death shortly after birth.
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References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

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