(2013) Zhang, Wei; Hui, Ken Y.; Gusev, Alexander; Warner, Neil; Evelyn Ng, Sok Meng; Ferguson, John; Choi, Murim; Burberry, Aaron; Abraham, Clara; Mayer, Lloyd; Desnick, Robert J.; Cardinale, Christopher J.; Hakonarson, Hakon; Waterman, Matti; Chowers, Yehuda; Karban, Amir; Brant, Steven R.; Silverberg, Mark S.; Gregersen, Peter K.; Katz, Seymour; Lifton, Richard P.; Zhao, Hongyu; Nuñez, Gabriel; Pe’er, Itsik; Peter, Inga; Cho, Judy H.
The Ashkenazi Jewish population has a several-fold higher prevalence of Crohn’s disease compared to non-Jewish European ancestry populations and has a unique genetic history. Haplotype association is critical to Crohn’s disease etiology in this population, most notably at NOD2, in which three causal, uncommon, and conditionally independent NOD2 variants reside on a shared background haplotype. We present an analysis of extended haplotypes which showed significantly greater association to Crohn’s disease in the Ashkenazi Jewish population compared to a non-Jewish population (145 haplotypes and no haplotypes with P-value < 10−3, respectively). Two haplotype regions, one each on chromosomes 16 and 21, conferred increased disease risk within established Crohn’s disease loci. We performed exome sequencing of 55 Ashkenazi Jewish individuals and follow-up genotyping focused on variants in these two regions. We observed Ashkenazi Jewish-specific nominal association at R755C in TRPM2 on chromosome 21. Within the chromosome 16 region, R642S of HEATR3 and rs9922362 of BRD7 showed genome-wide significance. Expression studies of HEATR3 demonstrated a positive role in NOD2-mediated NF-κB signaling. The BRD7 signal showed conditional dependence with only the downstream rare Crohn’s disease-causal variants in NOD2, but not with the background haplotype; this elaborates NOD2 as a key illustration of synthetic association.
