<unk>  is a rare congenital defect in which the major visceral organs are distributed abnormally within the chest and abdomen. Clinically Heterotaxy spectrum generally refers to any defect of left-right laterality and arrangement of the visceral organs, however Classical Heterotaxy requires multiple organs to be affected. This does not include the congenital defect situs inversus, which results when arrangement of all the organs in the abdomen and chest are mirrored, so the positions are opposite the normal placement. Situs inversus is the mirror image of situs solitus, which is normal asymmetric distribution of the abdominothoracic visceral organs.<unk>  can also be subdivided into left-isomerism and right isomerism based on the defects observed in the spleen, lungs and atria of the heart. Individuals with situs inversus or situs solitus do not experience fatal dysfunction of their organ systems, as general anatomy and morphology of the abdominothoracic organ-vessel systems are conserved. Due to abnormal arrangement of organs in<unk> , orientation across the left-right axis of the body is disrupted early in fetal development, resulting in severely flawed cardiac development and function in 50–80% of cases. They also experience complications with systemic and pulmonary blood vessels, significant morbidity, and sometimes death. All patients with<unk>  lack lateralization and symmetry of organs in the abdominal and thoracic cavities and are clinically considered to have a form of heterotaxy syndrome. Heterotaxy syndrome with atrial isomerism occurs in 1 out of every 10,000 live births and is associated with approximately 3% of congenital heart disease cases. Additional estimation of incidence and prevalence of isomerism proves difficult due to failure to diagnose and underestimation of the disease by clinicians. Furthermore, right isomerism is much more easily recognized than left isomerism, contributing to the failure to diagnose.<unk>  is a growing field of research with findings dating back to 1973.
Situs ambiguus
Situs inversus
Pulmonary agenesis
Double aortic arch
Pulmonary atresia
Gastroschisis
Diaschisis
Cranioschisis