Chimerism

How is Chimerism detected?

Blood testing and a full genetic profile must be done on the suspected patient as well as any consenting family members.

How does chimerism occur in the embryo?

Chimerism

Any human with Chimerism has a body that consists of two different sets of cells, which occurs when embryos, which were meant to be twins) get fused together. (In the early embryonic development stage.)

A rare biological disorder that genetically combines different tissues and DNA in a sole organism.

First Discovery of Chimerism in the U.S.

• Boston, Massachusetts, 1998
• Karen Keegan, Age 52
• First individual to be genetically tested for Chimerism in the U.S.
• Keegan needed to undergo a kidney transplant when it was discovered her DNA did not match her children's DNA

Though Chimerism has not been found to favor any one type of person or ethnicity, it is most often found in fraternal, vestigial and conjoined twins.

Chimerism in Humans

by Shelby Mayeran

The term "chimera" comes from the mythological creature pieced together by several different parts of other animals.

In humans, it is normally the result of two embryos combining.

Conclusions about Chimerism

Bibliography

Manifestation of Chimeras in Humans

Can anything be done?

• Chimeras may be artificial, twin/multiple gestation products, or tetragametic
• Artificial Chimeras are the product of the transfusion/transplantation of a second cell line or are the product of experimental/genetics engineering
• Twin/Multiple Gestation produces Chimerism through the transplacental passage of second cell line
• Tetragametic Chimerism occurs through the fusion of two fertilized zygotes
• Chimerism occurs frequently in other species such as cattle and mice.

• A person could be a chimera without ever knowing
• For example, a chimera could have different DNA for one organ in their body to the rest of their body
• In most cases, there are visible signs such as different colored eyes
• Chimerism can result in the formation of both female and male sexual organs (hermaphrodism)

Chimeras are two people who are fused at the cellular level. If you are one, you’re staying one, but there’s generally no need for anything to be done as there are usually no medical complications.

The fact that it’s possible to live as a chimera with no obvious side-effects or symptoms, prompts some doctors to believe that the condition is more common than people realise.

Chimerism can also occur artificially via transfusion/ transplantation of second cell line through experimental/genetics engineering and has been experimented in transgenic mice.

Transgenic refers to "an organism that contains genetic material into which DNA from an unrelated organism has been artificially introduced."

There are only 97 documented cases in the world.

Bultler, J. (n.d.). Chimerism Testing. Chimerism Testing. Retrieved December 1, 2013, from http://www.seattlecca.org/Chimerism-Testing.cfm

Eunis, E., Zuniga, J., & Romero, V. (n.d.). Chimerism and tetragametic chimerism in humans: implications in autoimmunity, allorecognition and tolerance.. National Center for Biotechnology Information. Retrieved November 4, 2013, from http://www.ncbi.nlm.nih.gov/pubmed/

Lam, V. (2006, November 20). THE TRUTH ABOUT CHIMERAS. Science Creative Quarterly. Retrieved November 26, 2013, from http://www.scq.ubc.ca/the-truth-about-chimeras/

Science Channel. (n.d.). What is a chimera?. Curiosity. Retrieved November 1, 2013, from http://curiosity.discovery.com/question/what-is-a-chimera

Other problems resulting from Chimerism

Abby and Brittany Hensel are Chimeric twins. They were born as conjoined twins, which means that as chimeras, they were originally fraternal twins, but their separate DNA strands fused and became one set of two separate strands.

• No way to predict recurrence risk

• Greater tolerance for organ/tissue transplantation

• Cause dilemmas in identity testing

• Possibly false negative results if wrong tissue selected

• Could appear as apparent mixed DNA sample

• Identify DNA source as coming from two individuals as opposed to one individual

• Cause dilemma in gender assignment (i.e. hermaphrodite)