ObjectiveTo explore the expression of growth associated protein-43 (GAP-43) in spasm segment and expansion segment of hirschsprung disease (HD), and to explore the pathogenesis of HD. MethodsThe expression of GAP-43 in 30 patients with HD who underwent surgical resection for absence of enteric plexuses from Jan. 2012 to Jun. 2013 in Shen zhen Children's Hospital were analyzed by using immunohistochemistry method and real-time PCR method. Aganglionic tissues of all patients were included as spasm group, and ganglionic tissues of the same patients were served as expansion group. Then comparison of the expression levels of GAP-43 mRNA and its protein between 2 groups was performed. Resultsof real-time RCR showed that the expression level of GAP-43 mRNA in expansion group was higher than that of spasm group (0.119 0 vs. 0.052 8, P<0.05). Immunohistochemistry results showed that GAP-43 protein expressed both in the myenteric plexus and ganglionic plexus of submucos in all patients, but lighter in spasm group. Compared with ganglionic plexus of circular muscle layer and longitudinal muscle layer/ganglionic plexus of submucosa in expansion group, the average optical density values at corresponding sites of intestinal tissues in spasm group were both lower (P<0.05). ConclusionExpression of GAP-43 protein is lower in spastic intestinal tissue of patients with HD, which suggests that down-regulation of GAP-43 protein may be a risk factor for HD.