A very rare disorder that appears after the first year and a half of life in previously healthy children. It is characterized by rapid-onset weight gain, hypothalamic dysfunction, breathing abnormalities, and autonomic system dysregulation. The hypothalamic dysfunction manifestations include inability to maintain normal water balance, high prolactin levels, low thyroid, low cortisol, and early or late puberty. The breathing abnormalities include sleep apnea and alveolar hypoventilation, requiring ventilation support. The autonomic system dysregulation includes eye abnormalities, intestinal abnormalities, temperature dysregulation, and low heart rhythm. This disorder requires early recognition because it may lead to cardiorespiratory arrest. Up to 40% of the patients develop tumors of neural crest origin. The disease is Monarch Disease Ontology term MONDO_0017408 (rapid-onset childhood obesity-hypothalamic dysfunction-hypoventilation-autonomic dysregulation syndrome). Also known as: ROHHAD, ROHHAD syndrome, ROHHADNET, Rapid-onset Obesity with Hypothalamic Dysfunction, Hypoventilation, and Autonomic Dysregulation, rapid-onset childhood obesity-hypothalamic dysfunction-hypoventilation-autonomic dysregulation-neural tumors syndrome, rapid-onset childhood obesity-hypothalamic dysfunction-hypoventilation-autonomic dysregulation-neural tumours syndrome, rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation, rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation syndrome.