Among patients with unspecific alterations or nearly normal biopsy, three had a genetic nature of different origin: one congenital central hypoventilation syndrome (CCHS) with mutation of PHOX2B gene, one neurodegenerative disorder Rett-like syndrome, with mutation in CDKL5, and one a CCP1 gene mutation. The gene discussed is PHOX2B; the disease is Ondine syndrome.