ABSTRACT
Hirschsprung disease (HSCR) is the most frequent developmental anomaly of the enteric nervous system, with an incidence of 1 in 5000 live births. Chronic intestinal pseudo-obstruction (CIPO) is less frequent and classified as neurogenic or myogenic. Isolated HSCR has an oligogenic inheritance with RET as the major disease-causing gene, while CIPO is genetically heterogeneous, caused by mutations in smooth muscle-specific genes. Here, we describe a series of patients with developmental disorders including gastrointestinal dysmotility, and investigate the underlying molecular bases. Trio-exome sequencing led to the identification of biallelic variants in ERBB3 and ERBB2 in 8 individuals variably associating HSCR, CIPO, peripheral neuropathy, and arthrogryposis. Thorough gut histology revealed aganglionosis, hypoganglionosis, and intestinal smooth muscle abnormalities. The cell type-specific ErbB3 and ErbB2 function was further analyzed in mouse single-cell RNA sequencing data and in a conditional ErbB3-deficient mouse model, revealing a primary role for ERBB3 in enteric progenitors. The consequences of the identified variants were evaluated using quantitative real-time PCR (RT-qPCR) on patient-derived fibroblasts or immunoblot assays on Neuro-2a cells overexpressing WT or mutant proteins, revealing either decreased expression or altered phosphorylation of the mutant receptors. Our results demonstrate that dysregulation of ERBB3 or ERBB2 leads to a broad spectrum of developmental anomalies, including intestinal dysmotility.
Subject(s)
Developmental Disabilities/genetics , Intestinal Pseudo-Obstruction/genetics , Mutation , Neuregulin-1/genetics , Receptor, ErbB-2/genetics , Receptor, ErbB-3/genetics , Adolescent , Animals , Child, Preschool , Developmental Disabilities/pathology , Disease Models, Animal , Female , Gastrointestinal Motility/genetics , Hirschsprung Disease/genetics , Hirschsprung Disease/pathology , Humans , Infant, Newborn , Intestinal Pseudo-Obstruction/pathology , Male , Mice , Models, Molecular , Pedigree , Phenotype , Pregnancy , Receptor, ErbB-2/chemistry , Receptor, ErbB-3/chemistry , Receptor, ErbB-3/deficiencyABSTRACT
The purpose of this study was to determine a possible association between two GABA transporter (GAT) single-nucleotide polymorphisms (SNPs), rs2697153 G>A in SLC6A1 (GAT-1) and rs2272400 C>T in SLC6A11 (GAT-3), and drug-resistant temporal lobe epilepsy (TLE). DNA was isolated from 138 TLE patients (from the neocortex) and 94 non-epileptic controls (from blood/buccal swaps), and amplified by polymerase chain reaction and subjected to restriction fragment length polymorphism assays. A subgroup of patients with a positive history of febrile seizures (FS+) and traumatic brain injury (TBI+) were investigated in a separate analysis. P values were obtained using the Chi-Square test and Fishers exact test. The GAT-1 SNP was different between patients and controls (p<0.05); the AA genotype was observed in 40% of the cases vs 23% of the controls (p<0.05). Thirty-one patients were FS+ and the GAT-3 CT genotype was observed significantly more frequently in the FS+ group (14%) than in the FS- group (1%; p<0.01). Thirteen patients were TBI+, and genotyping for GAT-1 and GAT-3 in these patients did not result in statistical differences between TBI+ and TBI- groups. The findings suggest that TLE is associated with GAT-1 and GAT-3 SNPs. More specifically, GAT-3 c1572T seems to be associated with TLE in patients with FS+. However, the pathophysiological consequences of these SNPs remain to be elucidated.
