Genome-wide association study identifies NRG1 as a susceptibility locus for Hirschsprung's disease

Abstract

Hirschsprung's disease (HSCR), or aganglionic megacolon, is a congenital disorder characterized by the absence of enteric ganglia in variable portions of the distal intestine. RET is a well-established susceptibility locus, although existing evidence strongly suggests additional loci contributing to sporadic HSCR. To identify these additional genetic loci, we carried out a genome-wide association study using the Affymetrix 500K marker set. We successfully genotyped 293,836 SNPs in 181 Chinese subjects with sporadic HSCR and 346 ethnically matched control subjects. The SNPs most associated with HSCR were genotyped in an independent set of 190 HSCR and 510 control subjects. Aside from SNPs in RET, the strongest overall associations in plausible candidate genes were found for 2 SNPs located in intron 1 of the neuregulin1 gene (NRG1) on 8p12, with rs16879552 and rs7835688 yielding odds ratios of 1.68 [CI 95%:(1.40, 2.00), P ‫؍‬ 1.80 ؋ 10 ؊8 ] and 1.98 [CI95%:(1.59, 2.47), P ‫؍‬ 1.12 ؋ 10 ؊9 ], respectively, for the heterozygous risk genotypes under an additive model. There was also a significant interaction between RET and NRG1 (P ‫؍‬ 0.0095), increasing the odds ratio 2.3-fold to 19.53 for the RET rs2435357 risk genotype (TT) in the presence of the NRG1 rs7835688 heterozygote, indicating that NRG1 is a modifier of HSRC penetrance. Our highly significant association findings are backed-up by the important role of NRG1 as regulator of the development of the enteric ganglia precursors. The identification of NRG1 as an additional HSCR susceptibility locus not only opens unique fields of investigation into the mechanisms underlying the HSCR pathology, but also the mechanisms by which a discrete number of loci interact with each other to cause disease.GWA ͉ RET

Genome-wide association studies - A summary for theclinical gastroenterologist

“…Other UC-specific regions are found at chromosome 1p36 and 12q15 [12] , however, at these loci, the exact disease genes remain to be identified. The association of classical HLA alleles and UC is well known [63] , and also (20q13) [202] Colorectal [120] If the authors mainly reported one region with several candidate genes the region is listed with the candidates in the region in parentheses, while if a specific gene was reported this is listed. Where more than one panel was used, but jointly analyzed, the sum of cases and controls in these panels is listed.…”

“…For a large proportion of familial cases and a considerable amount of sporadic cases, it has long been known that mutations in the RET gene are important [119] . In a small GWAS, Garcia-Barcelo et al [120] recently made several important discoveries. Firstly, they confirmed the associations previously detected at the RET locus.…”

Targeted Next-Generation Sequencing on Hirschsprung Disease: A Pilot Study Exploits DNA Pooling

“…Yet, despite the importance of RET, additional genes (acting either in conjunction or independently from RET) are necessary to explain not only the disease incidence but also its complex pattern of inheritance. Other HSCR genes identified so far mainly code for protein members of inter-related signaling pathways involved in the ENS development: endothelin receptor B (EDNRB), the transcriptional regulator SOX10, and the NRG1/ERBB2 signaling pathway gene (Hofstra et al, 1999;Heanue & Pachnis, 2007;Garcia-Barcelo et al, 2009). CDS mutations in genes other than RET thus far only account for 7% of the cases; however, the unexplained phenotypic variance in sporadic HSCR cases is still very high (>80%) (Gui et al, 2013).…”

“…All of the 14 genes known to cause HSCR in human newborns and ENS failure in the embryonic mouse (Table 1) were compulsorily included, while the other 48 genes (Table S1) were selected according to the following reasons: (1) key members in the same signaling pathway with know HSCR genes; (2) genes with suggestive association with HSCR in our previous GWAS study (Garcia-Barcelo et al, 2009); (3) supported by murine or functional studies as outlined in Table S1.…”

“…This pool was selected since all those five patients were also genotyped by Affymetrix 500K in our previous genome-wide association study (Garcia-Barcelo et al, 2009). The same RainDance technology was used to capture and enrich coding sequences of 62 candidate genes; however, DNA template was prepared using independent index primers for each individual without pooling and was then sequenced on an Illumina GAIIX platform (Illumina, San Diego, CA, USA).…”