Chimera (genetics)

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Chimera (genetics)

A chimera in genetics is an organism that contains cells derived from two or more distinct zygotes. This can result in an individual with two different sets of DNA, which can affect various aspects of the organism's phenotype.

Formation

Chimeras can form in several ways:

• Fusion of embryos: This occurs when two embryos merge at an early stage of development. The resulting organism has tissues with different genetic compositions.
• Transplantation: This can happen through medical procedures such as bone marrow transplants, where the recipient's body contains cells from the donor.
• Mutation: Rarely, a mutation can cause a single zygote to develop into a chimera.

Types of Chimeras

• Tetragametic chimera: This type of chimera is formed from the fusion of two fertilized eggs. Each egg contributes its own set of chromosomes, leading to an organism with two different cell lines.
• Microchimera: This occurs when a small number of cells from one individual are present in another individual. This can happen naturally, such as during pregnancy, where cells from the fetus can migrate into the mother's body and vice versa.

Detection

Chimerism can be detected through various methods:

• Genetic testing: DNA sequencing can reveal the presence of different genetic profiles within the same individual.
• Blood tests: Blood tests can identify different blood types or genetic markers that indicate chimerism.
• Tissue biopsy: Examining tissue samples under a microscope can show the presence of different cell lines.

Implications

Chimerism can have several implications:

• Medical: Chimerism can complicate organ transplants and blood transfusions, as the presence of different genetic profiles can affect compatibility.
• Forensic science: Chimerism can complicate DNA profiling in forensic investigations, as an individual may have multiple genetic profiles.
• Reproductive biology: Chimerism can affect fertility and the inheritance of genetic traits.

Notable Cases

There have been several notable cases of chimerism in humans and animals. These cases often attract significant attention due to their rarity and the unique challenges they present.

See Also

• Mosaicism
• Genetic disorder
• Genetic testing
• Embryology
• Transplant rejection