RET and Hirschsprung disease: Interestingly, different GPVs in this gene can cause different phenotypes: the milder MEN2A, some cases being associated with lichen amyloidosis or Hirschsprung's disease (with a lack of intestinal ganglia), or a more severe cancer phenotype, MEN2B, that can manifest as intestinal ganglioneuromatosis and mucosal neuromas (Brain et al.