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Genetic and Rare Diseases Information Center (GARD)

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Situs inversus


Other Names for this Disease

  • Situs inversus viscerum
  • SIV
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

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Our Answer

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What is situs inversus?

Situs inversus is a condition in which the internal organs of the abdomen (stomach) and thorax (chest) lie in mirror image of their normal body position. It can occur alone, without any other anomalies, or it can be  a part of a syndrome with various other defects. Situs inversus has been inherited in different ways in different families. Autosomal dominant, autosomal recessive, and X-linked inheritance have been reported. Treatment, when needed, is symptomatic and supportive.[1]
Last updated: 11/13/2014

What are the features of situs inversus?

In isolated situs inversus, there is a complete mirror image transposition of the thoracic (chest) and abdominal organs with preservation of the anterior-posterior (front-back) symmetry.[1] 
Last updated: 11/13/2014

What other symptoms or conditions may be associated with situs inversus?

Dextrocardia can occur with situs inversus. Dextrocardia means that the heart lies on the right side of the body, and the apex (tip) of the heart points to the right instead of the left. Situs inversus can also occur in association with syndromes such as Kartagener syndrome or primary ciliary dyskinesia (PCD). There may be incomplete transposition of thoracic or abdominal organs, as well as additional anomalies such as congenital heart disease, polysplenia (more than one spleen), asplenia (absent spleen), annular (ring-shaped) pancreas, horseshoe kidney, and diaphragmatic hernia.[1]
Last updated: 11/13/2014

How is situs inversus diagnosed?

A thorough physical examination and routine diagnostic tests can identify most cases of situs inversus.[1]
Last updated: 11/13/2014

How common is situs inversus?

The incidence of situs inversus is approximately 1 in 10,000 with slightly more males affected than females.[1]
Last updated: 11/13/2014

Is situs inversus inherited?

Situs inversus has been inherited in different ways in different families.  Several families have been described as showing autosomal dominant (a person must inherit only one copy of the gene from one parent to have the condition), autosomal recessive (the person must inherit two copies of the gene, one from each parent, to have the disorder), and X-linked inheritance. X-linked inheritance means that the gene for the disorder is located on the X chromosome. Females have two copies of the X chromosome, and they have to inherit two copies of that gene to have the disorder - one from their mother, and one from their father. However, males inherit only one copy of the X chromosome because they inherit a Y chromosome from their father, so they need only one copy of that gene from their mother to have the disorder.  Situs inversus appears to be genetically heterogeneous in humans, meaning that many genes may cause the disorder.[1]
Last updated: 11/13/2014

How might situs inversus be treated?

In isolated situs inversus, no treatment may be necessary. Where situs inversus is associated with other conditions such as primary ciliary dyskinesia (PCD), therapy is symptomatic (symptoms are treated, not the underlying cause). Most individuals with PCD experience chronic sinusitis, otitis media (earaches), and airway disease.[1]
Last updated: 11/13/2014

References
  • Tiller GE, Hamid R. Situs Inversus. NORD Guide to Rare Disorders. 2003;
Other Names for this Disease
  • Situs inversus viscerum
  • SIV
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.