Situs Invertus

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Victoria Navas Via-Dufresne
Science & Tech Editor

For the purpose of finding the organs of the human body, we have created a standard of what the human body looks like. Despite this, there are one in 10 000 individuals that do not fall in the standard body organization. These individuals have a congenital condition which causes for some or all of their organs to be mirrored, showing on the opposite side of the body.

Situs inversus, meaning in Latin “inverted position of internal organs”, has multiple manifestations.

Some may have situs inversus totalis, which causes all of their thoracic and abdominal organs to be mirrored. This is also known as situs inversus with dextrocardia, dextrocardia referring to the mirroring of the heart. This kind of situs inversus has the least amount of health problems, and can go unnoticed until the individual goes to the hospital for any other health issue, like appendicitis or rib fractures.

Some affected will have variations like situs inversus incompletus, or situs inversus with levocardia, where all of the organs are mirrored except for the heart. This condition is more severe than the previous as it can cause congenital heart disease. This variation is a lot less common, only affecting one in two million individuals.

Even rarer is situs ambiguus or heterotaxy, referring to organs of the body which are either duplicated or absent. In some cases the liver may be displaced, and in others, there can be an absence or a multitude of spleens. This condition can cause even greater health problems.

Situs inversus can be inherited or caused by a condition during embryonic development.

Being an autosomal recessive trait, if both parents of a child are either affected or are carriers of the trait in their chromosomes, they can pass on the trait to the next generation. Being a recessive trait, the individual would need to have both paternal and maternal chromosomes with the situs inversus gene in order to actually be affected. Otherwise, they would be carriers for the condition, but not have any expression of the trait.

The other cause for situs inversus is the condition known as PCD, or primary ciliary dyskinesia, which occurs during embryonic development and attacks the cilia, whose function it is to determine the position of the organs of the body. This condition gives the individual a 50% chance of developing situs inversus.

Those affected by PCD will have Kartagener syndrome whose effects are situs inversus, chronic sinusitis and bronchiectasis. This syndrome can also cause infertility in men since spermatozoa need cilia in order to function properly.

Situs inversus can cause problems when the individual needs organ transfer, since most organ donors are situs solitus (term referring to individuals with standard body organiation).

When doing a heart transplant for example, the heart would have to be reattached to the exact blood vessels, which can add steps in the transplant.

Individuals having this condition can wear a medical identification tag, which can help in case of any health problems. CPR can then be adapted to fit the person’s condition, and save that individual’s life.

Originally Published on Vol.50 Issue 02 on September 22nd, 2020

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