· 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.