Comparative genetic analysis of inflammatory bowel disease and type 1 diabetes implicates multiple loci with opposite effects
HUMAN MOLECULAR GENETICS
Authors: Wang, Kai; Baldassano, Robert; Zhang, Haitao; Qu, Hui-Qi; Imielinski, Marcin; Kugathasan, Subra; Annese, Vito; Dubinsky, Marla; Rotter, Jerome I.; Russell, Richard K.; Bradfield, Jonathan P.; Sleiman, Patrick M. A.; Glessner, Joseph T.; Walters, Thomas; Hou, Cuiping; Kim, Cecilia; Frackelton, Edward C.; Garris, Maria; Doran, James; Romano, Claudio; Catassi, Carlo; Van Limbergen, Johan; Guthery, Stephen L.; Denson, Lee; Piccoli, David; Silverberg, Mark S.; Stanley, Charles A.; Monos, Dimitri; Wilson, David C.; Griffiths, Anne; Grant, Struan F. A.; Satsangi, Jack; Polychronakos, Constantin; Hakonarson, Hakon
Abstract
Inflammatory bowel disease, including Crohn's disease (CD) and ulcerative colitis (UC), and type 1 diabetes (T1D) are autoimmune diseases that may share common susceptibility pathways. We examined known susceptibility loci for these diseases in a cohort of 1689 CD cases, 777 UC cases, 989 T1D cases and 6197 shared control subjects of European ancestry, who were genotyped by the Illumina HumanHap550 SNP arrays. We identified multiple previously unreported or unconfirmed disease associations, including known CD loci (ICOSLG and TNFSF15) and T1D loci (TNFAIP3) that confer UC risk, known UC loci (HERC2 and IL26) that confer T1D risk and known UC loci (IL10 and CCNY) that confer CD risk. Additionally, we show that T1D risk alleles residing at the PTPN22, IL27, IL18RAP and IL10 loci protect against CD. Furthermore, the strongest risk alleles for T1D within the major histocompatibility complex (MHC) confer strong protection against CD and UC; however, given the multi-allelic nature of the MHC haplotypes, sequencing of the MHC locus will be required to interpret this observation. These results extend our current knowledge on genetic variants that predispose to autoimmunity, and suggest that many loci involved in autoimmunity may be under a balancing selection due to antagonistic pleiotropic effect. Our analysis implies that variants with opposite effects on different diseases may facilitate the maintenance of common susceptibility alleles in human populations, making autoimmune diseases especially amenable to genetic dissection by genome-wide association studies.
Interleukin 27 polymorphisms in HCV RNA positive patients: is there an impact on response to interferon therapy?
BMC INFECTIOUS DISEASES
Authors: Zicca, Emilia; Quirino, Angela; Marascio, Nadia; Nucara, Stefania; Fabiani, Fernanda; Trapasso, Francesco; Perrotti, Nicola; Strazzulla, Alessio; Torti, Carlo; Liberto, Maria Carla; Foca, Alfredo
Abstract
Background: Interleukin 27 (IL-27) has pleiotropic properties that can either limit or enhance immune responses. Recent studies revealed that single nucleotide polymorphisms (SNPs) of the IL-27 promoter region modulate the development of infectious diseases and individual's susceptibility to therapeutic response. Little is known about the relationship between IL-27 single nucleotide polymorphisms and therapy response in patients infected by hepatitis C virus (HCV). In this study we have investigated the potential role of SNPs in the promoter region of IL27 p28 gene (alleles rs153109) on the outcome of HCV infected patients. Methods: rs153109, corresponding to position c.-964A>G of the IL-27 locus, was amplified from genomic DNA extracted from 15 patients with chronic hepatitis C stratified by sustained viral response (SVR), relapser and nonresponder, after treatment with peginterferon-alpha (PegIFN-alpha) combined with ribavirin (RBV). Amplification products were studied by direct sequencing. Results: This method has been applied in a preliminary study on patients with chronic hepatitis C to provide information for a standardized assay useful to genotyping of rs153109 SNPs of IL-27p28. The genotype distribution of the c.-964 A>G polymorphism was more present in patients who did not achieve a SVR. By contrast, the genotype G/G was absent in non-responder and relapser patients. Moreover, the analysis of allelic distribution of rs153109 highlighted a predominance of allele A in all genotypes in spite of allele G. Conclusions: Our work provides preliminary information for a standardized method potentially useful for genotyping rs153109, and suggests its utility as a candidate approach to evaluate IL-27 p28 polymorphisms as additional clinical predictors of response to therapies in HCV infected patients.