“…The variable phenotypes reported in CCHS patients carrying the same mutation also suggest the involvement of modifier genes of expressivity (Di Lascio et al, 2018a;Bachetti and Ceccherini, 2020). Mutations in genes other than PHOX2B, involved in the differentiation of neural crest cells (RET, GDNF, BDNF, GFRA1, PHOX2A, HASH-1, EDN1, EDN3, BMP2) or in oncogenes (BRAF) (Bolk et al, 1996;Amiel et al, 1998;Weese-Mayer et al, 2002Sasaki et al, 2003;Fernández et al, 2013;Al Dakhoul, 2017) have been found in some CCHS individuals. Remarkably, some of them are PHOX2B target genes (Flora et al, 2001;Bachetti et al, 2005), but the pathogenic role of these genetic variants is unclear (de Pontual et al, 2007).…”