Situs Inversus - Significance

Significance

Situs inversus is generally an autosomal recessive genetic condition, although it can be X-linked or found in identical "mirror" twins.

In the absence of congenital heart defects, individuals with situs inversus are phenotypically unimpaired, and can lead normal healthy lives, without any complications related to their medical condition. There is a 5 –10% prevalence of congenital heart disease in individuals with situs inversus totalis, most commonly transposition of the great vessels. The incidence of congenital heart disease is 95% in situs inversus with levocardia.

Many people with situs inversus totalis are unaware of their unusual anatomy until they seek medical attention for an unrelated condition. The reversal of the organs may then lead to some confusion, as many signs and symptoms will be on the 'wrong' side. For example, if an individual with situs inversus develops appendicitis, they will present to the physician with lower left abdominal pain, since that is where their appendix lies. Thus, in the event of a medical problem, the knowledge that the individual has situs inversus can expedite diagnosis. People with this rare condition may inform their physicians before an examination, so the physician can redirect their search for heart sounds and other signs. Wearing a medical identification tag can help to inform health care providers in the event the person is unable to communicate.

Situs inversus also complicates organ transplantation operations as donor organs will almost certainly come from situs solitus (normal) donors. As hearts and livers are chiral, geometric problems arise placing an organ into a cavity shaped in the mirror image. For example, a person with situs inversus who requires a heart transplant needs all the vessels to the transplant donor heart reattached to their existing ones. However, the orientation of these vessels in a person with situs inversus is reversed, necessitating steps so that the blood vessels join properly.