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Pathways systematically associated to Hirschsprung's disease.

ABSTRACT: Despite it has been reported that several loci are involved in Hirschsprung's disease, the molecular basis of the disease remains yet essentially unknown. The study of collective properties of modules of functionally-related genes provides an efficient and sensitive statistical framework that can overcome sample size limitations in the study of rare diseases. Here, we present the extension of a previous study of a Spanish series of HSCR trios to an international cohort of 162 HSCR trios to validate the generality of the underlying functional basis of the Hirschsprung's disease mechanisms previously found. The Pathway-Based Analysis (PBA) confirms a strong association of gene ontology (GO) modules related to signal transduction and its regulation, enteric nervous system (ENS) formation and other processes related to the disease. In addition, network analysis recovers sub-networks significantly associated to the disease, which contain genes related to the same functionalities, thus providing an independent validation of these findings. The functional profiles of association obtained for patients populations from different countries were compared to each other. While gene associations were different at each series, the main functional associations were identical in all the five populations. These observations would also explain the reported low reproducibility of associations of individual disease genes across populations.

SUBMITTER: Fernandez RM

PROVIDER: S-EPMC3879038 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

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Pathways systematically associated to Hirschsprung's disease.

Fernández Raquel M RM Bleda Marta M Luzón-Toro Berta B García-Alonso Luz L Arnold Stacey S Sribudiani Yunia Y Besmond Claude C Lantieri Francesca F Doan Betty B Ceccherini Isabella I Lyonnet Stanislas S Hofstra Robert Mw RM Chakravarti Aravinda A Antiñolo Guillermo G Dopazo Joaquín J Borrego Salud S

Orphanet journal of rare diseases 20131202

Despite it has been reported that several loci are involved in Hirschsprung's disease, the molecular basis of the disease remains yet essentially unknown. The study of collective properties of modules of functionally-related genes provides an efficient and sensitive statistical framework that can overcome sample size limitations in the study of rare diseases. Here, we present the extension of a previous study of a Spanish series of HSCR trios to an international cohort of 162 HSCR trios to valid ...[more]

PMID: 24289864

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Project description:BACKGROUND: Hirschsprung disease (HSCR) is a complex disorder with traditional germline mutations in RET in up to 30% of familial cases and in 3% of sporadic cases in a population-based series. We have previously demonstrated that an ancestral haplotype at the 5' end of RET (haplotype 0) was strongly associated with a large subset of isolated HSCR cases and that a putative low penetrance susceptibility locus was encompassed within this ancestral haplotype, anchored by exon 2 SNP A45A. OBJECTIVE: To determine the 5' extent of the HSCR-associated ancestral haplotype by defining the linkage disequilibrium breakpoint in search for the low penetrance susceptibility locus. METHODS: Systematic screening of the region upstream of the anchoring A45A SNP, comprising RET intron 1, exon 1, and promoter in 117 population-based HSCR cases and 100 controls. Dual luciferase assay to determine differential activities between SNP combinations near a transcription start site. RESULTS: New SNP's were found which formed upstream haplotypes, anchored by A45A, in linkage disequilibrium with HSCR (2 = 76.96, p<0.00000001). Linkage disequilibrium appeared to break at the -1249C/T SNP. Further, the HSCR-associated genotype (00) was found in >60% of HSCR but only 2% of controls. Because only 2 variants, -200A>G and -196C>A, lie within the promoter region and are in proximity to the transcriptional start site (at -195), we modelled these combinations into constructs for luciferase reporter assay. The HSCR-associated SNP combination showed the lowest activity and the control-associated combination, the highest. CONCLUSIONS: Our observations seem to discard the existence of a HSCR-causing mutation as it is conceived in the traditional sense, but strengthen the idea of a specific combination of variants conferring susceptibility to the disease in a low penetrance fashion. The data derived from our functional "in vitro" studies would suggest that the HSCR-associated haplotype 0 may result in a lower level of expression of the RET gene [corrected]

Project description:BackgroundETB has been reported to regulate neurogenesis and vasoregulation in foetal development. Its dysfunction was known to cause HSCR, an aganglionic colonic disorder with syndromic forms reported to associate with both small heads and developmental delay. We therefore asked, "is CNS maldevelopment a more general feature of ETB mutation?" To investigate, we reviewed the micro-CT scans of an ETB-/- model animal, sl/sl rat, and quantitatively evaluated the structural changes of its brain constituents.MethodsEleven neonatal rats generated from ETB+/- cross breeding were sacrificed. Micro-CT scans were completed following 1.5% iodine-staining protocols. All scans were reviewed for morphological changes. Selected organs were segmented semi-automatically post-NLM filtering: TBr, T-CC, T-CP, OB, Med, Cer, Pit, and S&I Col. Volumetric measurements were made using Drishti rendering software. Rat genotyping was completed following analysis. Statistical comparisons on organ volume, organ growth rate, and organ volume/bodyweight ratios were made between sl/sl and the control groups based on autosomal recessive inheritance. One-way ANOVA was also performed to evaluate potential dose-dependent effect.Resultssl/sl rat has 16.32% lower body weight with 3.53% lower growth rate than the control group. Gross intracranial morphology was preserved in sl/sl rats. However, significant volumetric reduction of 20.33% was detected in TBr; similar reductions were extended to the measurements of T-CC, T-CP, OB, Med, and Pit. Consistently, lower brain and selected constituent growth rates were detected in sl/sl rat, ranging from 6.21% to 11.51% reduction. Lower organ volume/bodyweight ratio was detected in sl/sl rats, reflecting disproportional neural changes with respect to body size. No consistent linear relationships exist between ETB copies and intracranial organ size or growth rates.ConclusionAlthough ETB-/- mutant has a normal CNS morphology, significant size reductions in brain and constituents were detected. These structural changes likely arise from a combination of factors secondary to dysfunctional ET-1/ET-3/ETB signalling, including global growth impairment from HSCR-induced malnutrition and dysregulations in the neurogenesis, angiogenesis, and cerebral vascular control. These changes have important clinical implications, such as autonomic dysfunction or intellectual delay. Although further human study is warranted, our study suggested comprehensive managements are required for HSCR patients, at least in ETB-/- subtype.

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Pathways systematically associated to Hirschsprung's disease.

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Pathways systematically associated to Hirschsprung's disease.

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