Reduced endothelin-3 expression in sporadic Hirschsprung disease

Background: Enteric aganglionosis in Hirschsprung disease has been linked to genes coding for endothelin-3 (EDN3) and the endothelin B receptor (EDNRB), but there is no such linkage in most patients with sporadic Hirschsprung disease. However, the similarity between the distal colonic aganglionosis in Hirschsprung disease and that due to EDN3 or EDNRB mutations led to the hypothesis that levels of expression of these genes might be affected in the absence of mutation, thus causing the Hirschsprung disease phenotype. The aim of this study was to determine EDN3 and EDNRB messenger RNA (mRNA) levels in tissue samples from patients with sporadic Hirschsprung disease. Methods: RNA and DNA were isolated from the ganglionic and aganglionic colonic segments of ten children with sporadic Hirschsprung disease, and from the colon of ten age-matched controls. The DNA was analysed for mutations in the genes coding for endothelin-3 (ET-3) and endothelin B receptor (ET-B) proteins. Relative levels of EDN3 and EDNRB mRNA were determined by semiquantitative transcriptase-polymerase chain reaction. Results: Three children had sequence variants in EDN3 and EDNRB. In the remaining seven patients, EDN3 mRNA levels were reduced in both the ganglionic and aganglionic colon compared with levels in controls; there was no difference in expression of EDNRB between groups. Conclusion: In the absence of mutation, EDN3 is downregulated in short-segment Hirschsprung disease, suggesting that this may be a common step leading to aganglionosis.