Analysis of the RET, GDNF, EDN3, and EDNRB genes in patients with intestinal neuronal dysplasia and Hirschsprung disease

Background-Hirschsprung disease (HSCR) is a frequent congenital disorder wi th an incidence of 1 in 5000 live births, characterised by the absence of p arasympathetic intramural ganglion cells in the hindgut resulting in intest inal obstruction in neonates and severe constipation in infants and adults. Intestinal neuronal dysplasia (IND) shares clinical features with HSCR but the submucosal parasympathetic plexus is affected. IND has been proposed a s one of the most frequent causes of chronic constipation and is often asso ciated with HSCR. Methods-We examined 29 patients diagnosed with sporadic HSCR, 20 patients w ith IND, and 12 patients with mixed HSCR/IND for mutations in the coding re gions of the RET, GDNF, EDNRB, and EDN3 genes. The entire coding regions we re analysed by single strand conformational polymorphism and DNA sequencing . Results-Only three RET mutations were detected in patients with HSCR. In pa tients with IND or a mixed HSCR/IND phenotype, no mutations in these genes were observed. While HSCR and HSCR/ IND showed over representation of a spe cific RET polymorphism in exon 2, IND exhibited a significantly lower frequ ency comparable with that of controls. Conclusions-The mutation frequency found in our sporadic HSCR patients (10% ) and the allelic distribution of RET polymorphisms are comparable with ear lier published data. A significantly different allelic distribution in an e stablished HSCR associated polymorphism argues against common genetic pathw ays for HSCR and IND.