Parasitic Twinning



Parasitic twins are combined identical twins in which the tissues of a severely defective twin (referred to as the parasitic twin) are dependent on the cardiovascular system of the other fully intact twin (referred to as the autositic twin) for survival.

Parasitic twins occur when a twin embryo begins developing in utero but the pair does not fully separate and one embryo maintains dominant development at the expense of its twin sibling. The underdeveloped twin which is considered the parasite, is incompletely formed making it fully dependent of the body functions of the autositic twin.

In majority of the cases that are seen, the phenotype that is displayed is one normal functioning individual with additional appendages or organs. Recently, there have been questions on whether or not these additional appendages are in fact another person or just a genetic mutation of the host’s body.

The autositic twin tends to experience several complications as a result of fulfilling the obligation of providing the needs for the parasitic twin. One of the most common conditions experienced by the autositic is Twin Reversed Arterial Perfusion otherwise known as TRAP sequences. This condition affects individuals who have additional torso or limbs. The major health problems with the TRAP sequence is heart failure due to the fact that the autositic twin’s heart must provide blood to both bodies.

Due to the cardiac complications that the autositic twin experiences, surgical removal of the parasitic twin is recommended. However, the extraction of the parasitic twin is an extremely risky procedure that occasional results in the death of the autositic twin.
Links: http://www.slate.com/articles/life/twins/2011/08/your_head_on_my_shoulder.html
https://ipfs.io/ipfs/QmXoypizjW3WknFiJnKLwHCnL72vedxjQkDDP1mXWo6uco/wiki/Vestigial_twin
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Comments

  1. Caitlyn GaffneyNovember 17, 2017 at 9:03 AM

    They showed this on Grey's Anatomy lol. They had like a two hour episode and they explained how risky surgery was and that it could result in death, but great news, no one died. I guess Grey's can be accurate sometimes. Anyways I did not know the details about this at all. It is crazy how the human body works, I am still amazed with every new thing I learn. Very interesting post, good job.

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