A laterization defect marked by asymmetric position of visceral organs usually occurring as a component of a wide variety of abnormalities. Transposition may be complete, with the heart, lungs and all abdominal organs reversed, or incomplete, manifesting itself as a simple reversal of the stomach or spleen. Associated malformations are variable and may include tetralogy of Fallot, transposition of great vessels, pulmonary valve stenosis, ventricular and atrial septal defects, asplenia-polysplenia. and other defects.