Subject(s)
5' Flanking Region/genetics , Hirschsprung Disease/genetics , Polymorphism, Single Nucleotide/genetics , Proto-Oncogene Proteins/genetics , Receptor Protein-Tyrosine Kinases/genetics , Alleles , Carcinoma, Medullary/genetics , DNA/chemistry , DNA/genetics , DNA Mutational Analysis , Gene Frequency , Haplotypes/genetics , Humans , Promoter Regions, Genetic/genetics , Proto-Oncogene Mas , Proto-Oncogene Proteins c-ret , Risk Factors , Thyroid Neoplasms/genetics , Tumor Cells, CulturedSubject(s)
Endothelin-3/genetics , Hirschsprung Disease/genetics , Waardenburg Syndrome/genetics , Amino Acid Sequence , DNA/chemistry , DNA/genetics , DNA Mutational Analysis , DNA-Binding Proteins/genetics , Family Health , Fatal Outcome , Female , Heterozygote , High Mobility Group Proteins/genetics , Hirschsprung Disease/pathology , Homozygote , Humans , Infant , Infant, Newborn , Male , Molecular Sequence Data , Mutation , Neural Crest/metabolism , Neural Crest/pathology , Pedigree , Phenotype , Receptor, Endothelin B , Receptors, Endothelin/genetics , SOXE Transcription Factors , Transcription Factors , Waardenburg Syndrome/pathologyABSTRACT
Hirschsprung disease (HSCR) is an inherited disorder characterised by absence of intrinsic ganglion cells in the distal gastrointestinal tract. Different susceptibility genes, involved in either the Ret-tyrosine kinase or the endothelin signalling pathways, contribute to HSCR phenotype. Interestingly, alterations of these genes are detected in only 30-50% of all HSCR patients, suggesting the involvement of modifier genes and/or additional genetic or environmental risk factors. In complex disorders common polymorphic variants can be associated with the disease phenotype, thus modifying the risk of recurrence. To investigate whether sequence variants of the RET proto-oncogene may be associated with the development of the HSCR phenotype, we analysed 92 Italian patients for the 2508C > T synonymous substitution in exon 14 (S836S) finding that the T allele is clearly less frequent than in control individuals (Fisher exact test P = 0.0002). On the other hand, this RET variant allele is overrepresented in patients affected with medullary thyroid carcinoma. Assuming a direct effect of this single-nucleotide polymorphism in predisposing to RET associated pathologies, we have performed functional tests which excluded any possible involvement of the C and T alleles in DNA-protein binding, transcript stability and RNA splicing and editing.
Subject(s)
Drosophila Proteins , Genetic Variation , Hirschsprung Disease/genetics , Polymorphism, Single Nucleotide/genetics , Proto-Oncogene Proteins/genetics , Receptor Protein-Tyrosine Kinases/genetics , Alleles , Carcinoma, Medullary/epidemiology , Carcinoma, Medullary/genetics , Child , Child, Preschool , Down Syndrome/epidemiology , Down Syndrome/genetics , Female , Genetic Predisposition to Disease/epidemiology , Genetic Predisposition to Disease/genetics , Hirschsprung Disease/epidemiology , Humans , Male , Proto-Oncogene Mas , Proto-Oncogene Proteins c-ret , Thyroid Neoplasms/epidemiology , Thyroid Neoplasms/geneticsSubject(s)
Drosophila Proteins , Enteric Nervous System/abnormalities , Genes, Homeobox/genetics , Hirschsprung Disease/genetics , Intestinal Diseases/genetics , DNA Mutational Analysis , Exons , Female , Humans , Intestinal Diseases/congenital , Intestines/abnormalities , Intestines/innervation , Intestines/pathology , Lod Score , Male , Pedigree , Polymerase Chain Reaction , Polymorphism, Single-Stranded Conformational , Proto-Oncogene Proteins/genetics , Proto-Oncogene Proteins c-ret , Receptor Protein-Tyrosine Kinases/geneticsABSTRACT
BACKGROUND: RET mutations have been reported variously to affect 7% to 41% of Hirschsprung's disease (HSCR) patients depending on familial or sporadic occurrence of the disease, length of aganglionosis and possible association with other disease phenotypes. The authors report a study of the incidence of RET mutations in unselected HSCR patients from two regional centers and correlate their genotypes and phenotypes. METHODS: The records of HSCR patients treated in 2 regional centers with a combined population of 5 million were reviewed, and blood samples were obtained from 57 patients. During the same period, 39 patients with similar demographic data refused or provided insufficient blood for study. DNA was extracted, and the 21 exons of the RET protooncogene were screened for mutations using denaturing gradient gel electrophoresis (DGGE). RESULTS: Of 57 patients, 48 were sporadic, and 9 were familial. Lengths of aganglionosis were total colonic, 4; long, 11; short, 39; ultrashort, 1; unclassified, 2. Associated anomalies were present in 20. Causative mutations were identified in 4 (7%): missense or "silent" in 3 (exons 5, 11, 13) and deletion in 1. The silent mutation of exon 11 recently has been shown to have effects on correct RET mRNA splicing. One mutation occurred in total colonic aganglionosis (25%), 1 in long segment dysganglionosis (9%), and 2 in short segment aganglionosis (5%). Surprisingly, all these mutations occurred in sporadic cases (10%). Five patients (9%) had rare polymorphic alleles at exon 14 (n = 1) and exon 18 (n = 4). Fifty patients (88%) showed common polymorphic alleles (sequence variants) in 1 or more exons (> 4, n = 5). CONCLUSIONS: RET mutation as a primary cause for Hirschsprung's disease in the general surgical population is less frequent than previously thought. This observation is compatible with the hypothesis that HSCR could be a polygenic disease caused by additive subclinical effects of more than one gene, including RET.
