Giving Birth to Someone Else’s Children? by Jessica Hutchison

Part V—Conclusion

Karen is a whole body chimera, otherwise known as a tetragametic chimera, meaning she resulted from the fusion of four gametes—two eggs and two sperm (see Figure 3). Therefore, her mother released two eggs that were separately fertilized by two sperm. This usually results in fraternal twins, but in Karen’s case, these two zygotes fused into one organism. One zygote went on to give rise to some of Karen’s cells, while the other zygote formed other cell types, giving Karen different genetic make-ups depending on what cell was examined.

Figure 3. Karen is the fusion of two zygotes, each resulting from the separate fertilization of two eggs by two sperm. If this fusion had not occurred, fraternal twins would have resulted. Therefore, different parts of Karen’s body carry different sets of genetic information.

The results were hard for Karen to cope with. Breaking the news to her sons was the hardest part for her. “I felt that part of me hadn’t passed on to them,” she explained.

Karen ended up accepting a kidney transplant from her husband and she is now a mixture of three genotypes.

Question

What are the implications of the discovery of Karen’s condition?

Originally published at http://www.sciencecases.org/chimera/chimera5.asp