Two novel mutations in exon 3 of PHOX2B gene: think about congenital central hypoventilation syndrome in patients with Hirschsprung disease

Background Congenital central hypoventilation syndrome(CCHS) is characterized by alveolar hypoventilationincreasing during sleep and affected patients are unable to perceive and respond to hypercarbiawith increased ventilation and arousal during sleep. PHOX2B gene mutations are considered as responsible for CCHS. Most of patients with CCHS are heterozygous for polyalanine expansion mutations ( PARMs) in exon 3, but 10% of patients with classic CCHS are heterozygous for non-polyalanine expansion mutations (NPARMs) of the PHOX2B gene.