CHRNA4 and dentin dysplasia: The study reveals three important findings: (1) The expression of NRG1 and its corresponding receptor ErbB3 is down-regulated in enteric ganglia and intestinal musculature of patients with DD compared to controls; (2) Whereas the expression of nAchR subunit β4 is decreased in patients with DD, other nAchR subunits remain unaltered; (3) NRG1 treatment promotes the mRNA expression of nAchR subunit b4 in enteric nerve cell cultures.