Pentalogy of Cantrell is a condition characterized by a combination of midline birth defects that can potentially involve the breastbone (sternum); the muscle that separates the chest cavity from the abdomen and aids in breathing (diaphragm); the thin membrane that lines the heart (pericardium); the abdominal wall; and the heart. It can have varying degrees of severity, and can be lethal. Most affected infants do not have all potential defects (incomplete Pentalogy of Cantrell). The exact cause of the condition is not known. Most cases occur sporadically, but familial cases have been reported.