Genetic variation in the GDNF promoter affects its expression and modifies the severity of Hirschsprung's disease (HSCR) in rats carrying Ednrbsl mutations

• · The − 613C > T mutation in the AGH strain decreased the expression of Gdnf.
• · Upstream region of exon 2 of Gdnf shown low transcriptional activity in AGH-Ednrbsl or LEH-Ednrbsl rats.
• · The − 613C > T mutation in AGH-Ednrbsl resulting in low expression of Gdnf was irrelevant to LEF1.
• · Expression of the Gdnf gene may modify the severity of HSCR in rats carrying Ednrbsl mutations.

Glial cell line-derived neurotrophic factor (GDNF) is necessary for the migration of neural crest stem cells in the gut. However, mutations in GDNF per se are deemed neither necessary nor sufficient to cause Hirschsprung's disease (HSCR). In a previous study, a modifier locus on chromosome 2 in rats carrying Ednrbsl mutations was identified, and several mutations in the putative regulatory region of the Gdnf gene in AGH-Ednrbsl rats were detected. Specifically, the mutation − 232C > T has been shown to be strongly associated with the severity of HSCR. In the present study, the influence of genetic variations on the transcription of the Gdnf gene was tested using dual-luciferase assay. Results showed that the mutation − 613C > T, located near the mutation − 232C > T in AGH-Ednrbsl rats, decreased Gdnf transcription in an in vitro dual-luciferase expression assay. These data suggested an important role of − 613C in Gdnf transcription. Expression levels of the Gdnf gene may modify the severity of HSCR in rats carrying Ednrbsl mutations.