In addition, case-control analysis demonstrated that RETrs2435357 is significantly correlated with HSCR (P = 2.2 × 10(-13)) with an odds ratio of 5.1 (95% confidence interval = 3.2-8.1).
We now show that a common non-coding RET variant within a conserved enhancer-like sequence in intron 1 is significantly associated with HSCR susceptibility and makes a 20-fold greater contribution to risk than rare alleles do.
Furthermore, there is strong evidence against linkage to two Hirschsprung disease (a condition that can cosegregate with neuroblastoma) susceptibility genes, RET and EDNRB.
Analysis of RET, ZEB2, EDN3 and GDNF genomic rearrangements in 80 patients with Hirschsprung disease (using multiplex ligation-dependent probe amplification).
Inactivating mutations of the RET proto-oncogene and of one of its soluble ligand molecules, glial cell line derived neurotrophic factor (GDNF), have been found in a subset of patients with Hirschsprung disease (HSCR).
Taken together, the low penetrance of the mutant gene, the lack of genotype-phenotype correlation, the sex-dependent effect of RET mutations and the variable clinical expression of the disease support the existence of one or more modifier genes in familial HSCR.
Germline RET mutations in Hirschsprung disease are mainly inactivating, and have been reported to account for up to 20 and 50% of sporadic and familial cases, respectively.
Such a functional effect of this common RET variant explains the under-representation of the whole haplotype and its role as a modifying factor in HSCR pathogenesis.
The aim of this study was to screen a panel of 16 cases of familial idiopathic slow-transit constipation, including 4 families in which there were relatives with Hirschsprung's disease, for RET and glial cell-derived neurotrophic factor mutations previously identified in Hirschsprung's disease.
MEN2A and MEN2B have recently been mapped within the centromeric region closely linked to RBP3 and D10S15 (which are located inside the deletion) and cosegregate with HSCR in at least two different pedigrees.
The germline mutation was detected because of the systematic genetic screening of the RET proto-oncogene, which is useful for genetic counseling of potential risk of HSCR and MTC in other family members.
This distinctive feature of RET mutations associated with Hirschsprung's disease and of the RET mutations associated with thyroid cancer indicates a basic biological difference between the mutational events leading to the different phenotypes.
Here, we describe a mutation of the human gene for endothelin 3 (EDN3), homozygously present in a patient with a combined Waardenburg syndrome type 2 (WS2) and HSCR phenotype (Shah-Waardenburg syndrome).
In addition, there was strong evidence against linkage to two Hirschsprung disease susceptibility genes (RET and EDNRB), a condition that can cosegregate with neuroblastoma as in one of the kindreds tested here.
Recently, the glial cell line-derived neurotrophic factor (GDNF) was identified as one of the ligands of the RET, and GDNF (5p12-p13.1) mutations were also found in association with RET mutations in HSCR patients.
Future studies investigating the disease-associated mutations in the already identified HSCR genes should provide insights into the genetic basis of HSCR in twins.
GDNF sequence variants including R93W have been suggested previously to represent low penetrance susceptibility mutations for Hirschsprung disease and the R93W was not identified in 376 control alleles studied by others.