Congenital central hypoventilation syndrome (CCHS) and PHOX2B pathogenic variants

Congenital central hypoventilation syndrome (CCHS) is characterized by disordered respiratory control (alveolar hypoventilation) and autonomic nervous system (ANS) regulation. Diagnosis is made in the absence of primary lung, cardiac, or neuromuscular disease or an identifiable brainstem lesion that might account for the entire phenotype inclusive of ANS dysregulation (ANSD) (Weese-Mayer et al., 2010, [1]). Alveolar hypoventilation, as demonstrated by diminutive tidal volumes and monotonous respiratory rates, results in hypoxemia and hypercarbia. Disordered respiratory control, as demonstrated by absent/severely attenuated ventilatory, behavioral, and arousal responses to endogenous/exogenous hypoxemia/hypercarbia, occurring at rest or in activities of daily living results in severe physiologic compromise (Weese-Mayer et al., 2010, [1]). The detection of pathogenic variants in the pairedlike homeobox 2B (PHOX2B) gene allows the confirmation of the diagnosis of CCHS. Because of the role of PHOX2B in early embryologic development of the autonomic nervous system (ANS), characteristic features of physiologic ANS dysregulation (ANSD) in CCHS are anticipated (Table 90.1).