What Is Heterotaxy Syndrome

Heterotaxy syndrome has captured the attention of medical researchers and healthcare professionals because it is highly linked to cardiac and other internal conditions that escalate morbidity and mortality rates.

Heterotaxy syndrome is a rare congenital condition characterized by abnormal positioning or arrangement of internal organs in the chest and abdomen. It occurs when organs develop on the opposite side or in an abnormal location. This disorder can affect various organs, including the heart, liver, spleen, and intestines, leading to potential health complications.

The following article will explore the causes, symptoms, diagnosis, and treatment options for heterotaxy syndrome, as well as frequently asked questions.


Heterotaxy Syndrome, also known as situs ambiguus, is a birth disorder characterized by the abnormal positioning or arrangement of internal organs within the chest and abdomen. One out of every 10,000 babies worldwide is born with heterotaxy syndrome. Because the condition is sometimes diagnosed later in life, some researchers expect it to be more prevalent than reported.1

This condition presents significant challenges due to its diverse range of associated anomalies. Heterotaxy Syndrome is often linked to complex cardiac lesions, such as atrioventricular septal defects, and can manifest in various forms, including right isomerism, left isomerism, or atrial isomerism. Typically, heterotaxy patients are classified into either asplenia syndrome or polysplenia syndrome,  heterotaxy with right atrial isomerism, or heterotaxy with left atrial isomerism (see Figure 1).2

Figure 1: The internal anatomy of heterotaxy syndrome is shown schematically. Situs solitus refers to the normal positioning of the internal organs. Situs inversus totalis is the total reverse of all structures, from left to right. The types asplenia and polysplenia are a mixture of right-sided and wrong-sided structures. Source (3)

Causes of heterotaxy syndrome

While the exact causes of Heterotaxy Syndrome remain largely unknown, research suggests that genetic factors play a crucial role in its development. Mutations in genes responsible for determining left-right asymmetry during embryonic development have been identified in some cases. Additionally, it is proposed that environmental and maternal health conditions also play a decisive role. Family history of malformations (odds ratio 5.1), maternal diabetes (odds ratio 5.5), and cocaine use during the first trimester by the mother (odds ratio: 3.7) have also been implicated. Further research is needed to fully comprehend the complex interplay between genetic and environmental factors in the development of this condition.4,5

Signs and symptoms of heterotaxy syndrome

The signs and symptoms of Heterotaxy Syndrome can vary significantly depending on the specific type and severity of organ involvement. In cases of right isomerism, the abnormal arrangement of organs may include a bilobed lung, bilateral right-sidedness, and multiple spleens (polysplenia syndrome). Patients with left isomerism may exhibit mirror-imaged thoracic and abdominal organs, bilateral left-sidedness, and a single midline spleen. Atrial isomerism is characterized by abnormalities in the atrial appendages and is associated with complex cardiac malformations.2,3

Cardiac anomalies are a hallmark of heterotaxy syndrome, with atrioventricular septal defects being particularly common. Other heart defects, such as transposition of the great vessels, ventricular septal defects, and abnormalities of the pulmonary veins, may also be present. Additionally, abnormalities in the positioning and structure of abdominal organs, including the liver, spleen, and intestines, can lead to complications such as biliary atresia, malrotation, and intestinal malformations.2,5

Management and treatment for heterotaxy syndrome

Managing Heterotaxy Syndrome requires a multidisciplinary approach involving various medical specialists. Cardiologists, gastroenterologists, surgeons, and geneticists work together to provide comprehensive care tailored to each individual's needs. Treatment plans focus on addressing specific symptoms and complications.

Surgical interventions are often necessary to correct congenital heart defects and alleviate complications related to abnormal organ positioning. Medications may be prescribed to manage associated conditions such as arrhythmias or infections. In cases where organ function is severely compromised, organ transplantation may be considered. Regular follow-up care and monitoring are essential to ensure optimal management and address potential long-term complications.2,3


Diagnosing heterotaxy syndrome requires a comprehensive evaluation that includes a detailed medical history, thorough physical examination, and a range of imaging tests. Echocardiography plays a central role in assessing cardiac abnormalities and their impact on organ function. Abdominal ultrasound can provide valuable information on the positioning and structure of abdominal organs, while magnetic resonance imaging (MRI) offers a more detailed view of complex anatomical relationships.

Specialized procedures such as cardiac catheterization and endoscopy may be performed to obtain additional information about organ structure and function. Genetic testing may be recommended to identify potential genetic mutations and provide insights into familial patterns.3


How can I prevent heterotaxy syndrome?

Heterotaxy Syndrome cannot be prevented as its exact causes are not fully understood, but maintaining a healthy lifestyle and seeking regular prenatal care may contribute to overall fetal well-being.

How common is heterotaxy syndrome?

1 in every 10,000 babies worldwide is born with heterotaxy syndrome.

Who is at risk of heterotaxy syndrome?

Heterotaxy Syndrome can occur in individuals with or without a family history of the condition. While most cases of heterotaxy syndrome are rare, certain genetic mutations may increase the risk. Additionally, environmental factors and maternal health conditions may also play a role, although the specific risk factors are not fully known.

When should I see a doctor?

A doctor should be consulted if one notices any signs or symptoms associated with the condition, such as abnormal heart rhythms, difficulty breathing, feeding difficulties, or recurrent infections. Additionally, if there is a family history of heterotaxy syndrome, seeking medical advice can help provide guidance and support.


In conclusion, heterotaxy syndrome is a rare congenital disorder characterized by abnormal organ arrangement within the chest and abdomen. It is often associated with complex cardiac lesions and can present in various forms, such as right isomerism, left isomerism, or atrial isomerism. While the exact causes are not fully understood, genetic and environmental factors are believed to contribute. Prompt and comprehensive management involving a multidisciplinary team is crucial to addressing the diverse range of symptoms and complications associated with this condition. Ongoing research and advancements in diagnostic techniques and treatment options offer hope for improved outcomes for individuals living with heterotaxy syndrome.


  1. Lin AE, Krikov S, Riehle-Colarusso T, Frias JL, Belmont JW, Anderka M, et al. Laterality defects in the national birth defects prevention study (1998-2007): Birth prevalence and descriptive epidemiology. American Journal of Medical Genetics [Internet]. 2014 Aug 6;164(10):2581–91. Available from: https://doi.org/10.1002/ajmg.a.36695
  2. Kim S. Heterotaxy Syndrome. Korean Circulation Journal [Internet]. 2011 Jan 1;41(5):227. Available from: https://doi.org/10.4070/kcj.2011.41.5.227
  3. Degenhardt K, Rychik J. Fetal Situs, Isomerism, Heterotaxy Syndrome: Diagnostic Evaluation and Implication for Postnatal Management. Current Treatment Options in Cardiovascular Medicine [Internet]. 2016 Nov 14; Available from: https://doi.org/10.1007/s11936-016-0494-2
  4. Belmont JW, Mohapatra B, Towbin JA, Ware SM. Molecular genetics of heterotaxy syndromes. Current Opinion in Cardiology [Internet]. 2004 May 1;19(3):216–20. Available from: https://doi.org/10.1097/00001573-200405000-00005
  5. Kuehl KS, Loffredo CA. Risk factors for heart disease associated with abnormal sidedness. Birth Defects Research [Internet]. 2002 Oct 23;66(5):242–8. Available from: https://doi.org/10.1002/tera.10099
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Abdullah Khalil Abdullah Mutahar

Master of Science - MS, Biomedical and Molecular Sciences with Management, University of Dundee

Abdullah holds an MSc in Biomedical and Molecular Sciences with Management from the University of Dundee, Scotland, and a BSc in Biological Sciences from Goethe University Frankfurt, Germany. He has keen interests in immunology, cosmetology, nutrition, and public health. Abdullah sees his involvement in an online medical library as an ideal way to simplify complex information and promote health awareness.

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