dispermic chimera

genetics

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July 20, 2026

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A dispermic chimera is a genetic phenomenon where an organism contains at least two different sets of DNA, typically resulting from the fusion of two zygotes. This means the individual originates from four gametes (sex cells) instead of the usual two.

Dispermic chimerism can occur when two sperm fertilize two eggs, and these fertilized eggs then fuse. Alternatively, a single zygote can fuse with a fertilized polar body. The resulting organism, a tetragametic individual, can have tissues derived from one or both zygotes. Observable signs can include differing eye colors, patchy skin, or ambiguous genitalia, though often there are no visible symptoms and the condition is detected through genetic analysis. This is distinct from mosaics, which arise from a single zygote, and hybrids, which result from the cross of two species.1

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chimera
In dispermic chimeras, two eggs that have been fertilized by two sperm fuse together, producing a so-called tetragametic individual—an individual originating from four gametes, or sex cells. (Under normal circumstances, in the absence of zygote fusion, two fertilized eggs result in the production of dizygotic, or…
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In dispermic chimeras, two eggs that have been fertilized by two sperm fuse together, producing a so-called tetragametic individual—an individual originating from four gametes, or sex cells. (Under normal circumstances, in the absence of zygote fusion, two fertilized eggs result in the production of dizygotic, or…
Read More