DEEAH syndrome is an autosomal recessive multisystemic disorder with onset in early infancy. Affected individuals usually present in the perinatal period with respiratory insufficiency, apneic episodes, and generalized hypotonia. The patients have failure to thrive and severely impaired global development with poor acquisition of motor, cognitive, and language skills. Other common features include endocrine, pancreatic exocrine, and autonomic dysfunction, as well as hematologic disturbances, mainly low hemoglobin. Patients also have dysmorphic and myopathic facial features. Additional more variable features include seizures, undescended testes, and distal skeletal anomalies. Death in early childhood may occur (summary by Schneeberger et al., 2020).

Neurodevelopmental disorder with dysmorphic facies, impaired speech, and hypotonia (NEDDISH) is an autosomal recessive disorder characterized by global developmental delay and mildly to severely impaired intellectual development with poor speech and language acquisition. Some patients may have early normal development with onset of the disorder in the first years of life. More variable neurologic abnormalities include hypotonia, seizures, apnea, mild signs of autonomic or peripheral neuropathy, and autism. Aside from dysmorphic facial features and occasional findings such as scoliosis or undescended testes, other organ systems are not involved (summary by Schneeberger et al., 2020).

Congenital central hypoventilation syndrome (CCHS) represents the extreme manifestation of autonomic nervous system dysregulation (ANSD) with the hallmark of disordered respiratory control. The age of initial recognition of CCHS ranges from neonatal onset (i.e., in the first 30 days of life) to (less commonly) later onset (from 1 month to adulthood). Neonatal-onset CCHS is characterized by apparent hypoventilation with monotonous respiratory rates and shallow breathing either during sleep only or while awake as well as asleep; ANSD including decreased heart rate beat-to-beat variability and sinus pauses; altered temperature regulation; and altered pupillary response to light. Some children have altered development of neural crest-derived structures (i.e., Hirschsprung disease, altered esophageal motility/dysphagia, and severe constipation even in the absence of Hirschsprung disease) and/or tumors of neural crest origin (neuroblastoma, ganglioneuroma, and ganglioneuroblastoma). Neurocognitive delay is variable, and possibly influenced by cyanotic breath holding, prolonged sinus pauses, need for 24-hour/day artificial ventilation, and seizures. Later-onset CCHS is characterized by alveolar hypoventilation during sleep and attenuated manifestations of ANSD.