ABSTRACT
Hirschsprung disease (HSCR, aganglionic megacolon) is a complex genetic disorder of the enteric nervous system (ENS) characterized by the absence of enteric neurons along a variable length of the intestine. While rare variants (RVs) in the coding sequence (CDS) of several genes involved in ENS development lead to disease, the association of common variants (CVs) with HSCR has only been reported for RET (the major HSCR gene) and NRG1. Importantly, RVs in the CDS of these two genes are also associated with the disorder. To assess independent and joint effects between the different types of RET and NRG1 variants identified in HSCR patients, we used 254 Chinese sporadic HSCR patients and 143 ethnically matched controls for whom the RET and/or NRG1 variants genotypes (rare and common) were available. Four genetic risk factors were defined and interaction effects were modeled using conditional logistic regression analyses and pair-wise Kendall correlations. Our analysis revealed a joint effect of RET CVs with RET RVs, NRG1 CVs or NRG1 RVs. To assess whether the genetic interaction translated into functional interaction, mouse neural crest cells (NCCs; enteric neuron precursors) isolated from embryonic guts were treated with NRG1 (ErbB2 ligand) or/and GDNF (Ret ligand) and monitored during the subsequent neural differentiation process. Nrg1 inhibited the Gdnf-induced neuronal differentiation and Gdnf negatively regulated Nrg1-signaling by down-regulating the expression of its receptor, ErbB2. This preliminary data suggest that the balance neurogenesis/gliogenesis is critical for ENS development.
Subject(s)
Genetic Variation/genetics , Hirschsprung Disease/genetics , Neuregulin-1/genetics , Proto-Oncogene Proteins c-ret/genetics , Animals , Case-Control Studies , Cells, Cultured , China , Female , Genomics , Genotype , Glial Cell Line-Derived Neurotrophic Factor/genetics , Glial Cell Line-Derived Neurotrophic Factor/metabolism , HapMap Project , Hirschsprung Disease/metabolism , Humans , Intestines/cytology , Intestines/innervation , Linkage Disequilibrium , Male , Mice , Mutation , Neural Crest/cytology , Neuregulin-1/metabolism , Phenotype , Proto-Oncogene Proteins c-ret/metabolism , Receptor, ErbB-2/genetics , Receptor, ErbB-2/metabolism , Risk Factors , TransgenesABSTRACT
BACKGROUND: Anorectal malformations (congenital absence of the anal opening) are among the most common pediatric surgical problems and carry a significant chronic morbidity. METHODS: Direct sequencing was used to screen 88 anorectal malformations patients for mutations and polymorphisms in SHH and GLI3. These genes were chosen according to the phenotype presented by mutant mice and their expression patterns. RESULTS: We report on 10 GLI3 variants (IVS3+141C>G, T183A, IVS4+124T>C, IVS7+17G>A, IVS8+1 G>C, N503N, P941P, P998L, A1005A, A1039A) and four SHH mutation/variants (IVS1-49C>T, IVS2+111A>C, L214L, G290D). CONCLUSIONS: These variants are not over-represented in the healthy population and most are predicted to be benign. This study conveys the problematic assessment of the pathogenic role in disease of rare point mutations and variants.
