Ondine's curse refers to a condition present from birth that disrupts the ability to control breathing during sleep, while breathing remains normal when awake. The autonomic regulation of breathing is compromised, but the voluntary control that functions during wakefulness is usually unaffected. Additionally, individuals may experience issues with the movement of the esophagus and colon. Decreased esophageal motility leads to slow passage of food to the stomach, while reduced colon motility results in Hirschsprung disease (megacolon), causing severe constipation and possible obstruction. An unusually slow heart rate may also be present. Some affected individuals may have distinctive facial features, such as downward-slanting eyes, a small nose, a triangular-shaped mouth, and ears that are low-set and rotated backward. This condition is also known as central congenital hypoventilation syndrome (CCHS), CCHS with Hirschsprung disease, congenital failure of autonomic control, central hypoventilation syndrome, and central hypoventilation with severe hypoventilation. The name "Ondine's curse" is inspired by the legend of Ondine, a water nymph who fell in love with a knight and was cursed to remain awake to breathe.
