A new experimental approach is required in the molecular analysis of intestinal neuronal dysplasia type B patients

Intestinal neuronal dysplasia type B (INDB) is characterized by the malformation of the parasympathetic submucous plexus of the gut. It is generally accepted that INDB has a genetic basis, and several genes produce an INDB-like phenotype in mice when disrupted, such as EDNRB. However, no mutations associated with this disease have been identified in several series analysed. In the present studu, we sought to determine whether the EDNRB/EDN3 signalling pathway plays a role in the pathogenesis of INDB in humans. Denaturing high performance liquid chromatography (dHPLC) techniques were employed to screen the EDNRB and EDN3 coding regions in 23 INDB patients. In addition, association studies were performed on these genes with single nucleotide polymorphisms strategically selected and genotyped by TaqMan technology. Although several novel variants were detected in both genes, none of these variants appeared to play a functional role in protein function or expression. Our results indicate that additional screening of other candidate genes in larger patient series is required to elucidate the molecular basis of INDB. Additionally, the systematic lack of positive results in the screening of candidate genes for INDB reported in the literature, together with our results, leads us to propose that INDB may alternatively arise as a consequence of gain of function mutations in genes related to enteric nervous system development. Therefore, the use of different molecular approaches, such as screening for genetic duplication or enhancer mutations, is recommended for future studies on the genetic basis of INDB.