Clinical importance of weight gain and associated factors in patients with moderate to severe ulcerative colitis: results from the MOSAIK cohort in Korea.

BACKGROUND: Many patients with ulcerative colitis (UC) gain weight after treatment. However, the clinical significance of weight gain in these patients remains unclear. This study aimed to evaluate body weight changes after treatment in patients newly diagnosed with moderate-to-severe UC and their effects on patients' prognosis. METHODS: The change in weight between diagnosis and 1 year after treatment in 212 patients enrolled in the MOSAIK cohort (mean age, 40 years; males, 60%) was analyzed. Significant weight gain was defined as a weight increase of ≥ 5% from the baseline at 1 year. Factors associated with significant weight gain and the effect of significant weight gain on the risk of major adverse outcomes (clinical relapse, hospitalization, and new use of steroids or biologics) during a follow-up period of 20 months were evaluated. RESULTS: Mean weight gain at 1 year was 1.7 ± 4.2 kg. The proportion of overweight/obese patients increased by 9.0% from 37.9% to 46.9%. Thirty-two percent had significant weight gain; extensive colitis at diagnosis was the only factor associated with significant weight gain (odds ratio 6.5, 95% confidence interval 1.4-31.0, p = 0.006). In multivariable analysis, significant weight gain was not associated with the risk of major adverse outcomes. Weight loss symptoms at diagnosis were associated with an increased risk for new steroid use after 1 year. CONCLUSIONS: Approximately one-third of patients with moderate-to-severe UC had significant weight gain after 1 year of treatment. However, significant weight gain was not associated with the patient's prognosis.

Genome-wide association analysis reveals the associations of NPHP4, TYW1-AUTS2 and SEMA6D for Behçet's disease and HLA-B*46:01 for its intestinal involvement.

BACKGROUND: Intestinal involvement in Behçet's disease (BD) is associated with poor prognosis and is more prevalent in East Asian than in Mediterranean populations. Identifying the genetic causes of intestinal BD is important for understanding the pathogenesis and for appropriate treatment of BD patients. METHODS: We performed genome-wide association studies (GWAS) and imputation/replication genotyping of human leukocyte antigen (HLA) alleles for 1,689 Korean and Turkish patients with BD (including 379 patients with intestinal BD) and 2,327 healthy controls, followed by replication using 593 Japanese patients with BD (101 patients with intestinal BD) and 737 healthy controls. Stratified cross-phenotype analyses were performed for 1) overall BD, 2) intestinal BD, and 3) intestinal BD without association of overall BD. RESULTS: We identified three novel genome-wide significant susceptibility loci including NPHP4 (rs74566205; P=1.36 × 10-8), TYW1-AUTS2 (rs60021986; P=1.14 × 10-9), and SEMA6D (rs4143322; P=5.54 × 10-9) for overall BD, and a new association with HLA-B*46:01 for intestinal BD (P=1.67 × 10-8) but not for BD without intestinal involvement. HLA peptide binding analysis revealed that Mycobacterial peptides, have a stronger binding affinity to HLA-B*46:01 compared to the known risk allele HLA-B*51:01. CONCLUSIONS: HLA-B*46:01 is associated with the development of intestinal BD; NPHP4, TYW1-AUTS2, and SEMA6D are susceptibility loci for overall BD.

What Is the Relationship between Antioxidant Efficacy, Functional Composition, and Genetic Characteristics in Comparing Soybean Resources by Year?

The aim of this study was to analyze the physiological activity of 48 soybean resources harvested in 2020 to identify the soybean resources' relationships with individual isoflavone compounds and their genetic properties. These data will subsequently be compared with the research results on soybeans harvested in 2019. Initially, with respect to the physiological activity (6 types) and substances (19 types), this study evaluated the differences between the cultivation year (two years), seed coat color (three colors), and the interaction of the year and seed coat color of soybeans through ANOVA. Among the physiological activities, there were differences in the estrogen, estrogen receptor alpha, and UCP-1 (uncoupling protein-1) activities depending on the cultivation year. Moreover, there were differences in NO (nitric oxide), revealing differences in the ABTS (2, 2'-azino-bis-3ethylbenzo-thiazoline-6-sulfonic acid) and DPPH (2, 2-diphenyl-2-picrylhydrazyl) radical scavenging activities due to the seed coat color and the interaction of the year and seed coat color. Soybeans harvested in 2020 exhibited increased ABTS, DPPH, and NO inhibitory activities and reduced estrogen, estrogen receptor alpha, and UCP-1 activities compared to those harvested in 2019. According to the ANOVA results, eight of the nineteen individual derivatives illustrated yearly differences, while three derivatives displayed differences due to the seed coat color. Secondly, according to the relationship between the efficacy, derivative substances, and genetic properties, it was determined that genistein 7-O-(2″-O-apiosyl)glucoside (F5) is the individual isoflavone derivative that affected the six types of physiological activity, on which the genome-wide association study (GWAS) showed no significant differences for genetic properties. These results were inconsistent with the 2019 data, where three types of individual compounds, including F5, were proposed as substances that correlated with efficacy and there was a high correlation with genetic properties. Therefore, this study selected B17, B23, B15, B24, and Y7 as excellent varieties that are stable and highly functional in the cultivation environment, producing only small annual differences. The results of this study will be utilized as basic data for predicting soybean varieties and their cultivation, which have high environmental stability under climate variation and properly retain the functional substances and efficacy.

A Correlation Study on In Vitro Physiological Activities of Soybean Cultivars, 19 Individual Isoflavone Derivatives, and Genetic Characteristics.

The functionality of soybeans is an important factor in the selection and utilization of excellent soybean cultivars, and isoflavones are representative functional substances in soybeans, which exhibit effects on antioxidants, estrogen activity, and cancer, and prevent cardiovascular diseases. This study analyzed ABTS, DPPH, estrogen, ER (ER) alpha, UCP-1, and NO inhibition activities in 48 types of soybean cultivars, as well as the relationship with 19 isolated types of individual isoflavone derivatives. Statistical analysis was conducted to find individual isoflavone derivatives affecting physiological activities, revealing the high correlation of three types of derivatives: genistein 7-O-(6″-O-acetyl)glucoside (6″-O-acetylgenistin), genistein 7-O-(2″-O-apiosyl)glucoside, and glycitein. Based on these results, 15 types of soybean cultivars were selected (one control type, seven yellow types, six black types, and one green type), which have both high physiological activities and a high content of individual isoflavone derivatives. In addition, these high correlations were further verified through a genome-wide association study (GWAS) to determine the association between activities, substances, and genetic characteristics. This study comprehensively describes the relationship between the specific physiological activities of soybean resources, individual isoflavone derivative substances, and SNPs, which will be utilized for in-depth research, such as selection of excellent soybean resources with specific physiological activities.

Inter-observer variability of experts and trainees for the diagnosis of reflux esophagitis: Comparison of linked color imaging, blue laser imaging, and white light imaging.

OBJECTIVES: Diagnosis of reflux esophagitis according to the Los Angeles classification minimal change (LA-M) has a low inter-observer agreement. We aimed to investigate whether the inter-observer agreement of reflux esophagitis was better when expert endoscopists read the endoscopic images, or when the linked color imaging (LCI) or blue laser imaging (BLI)-bright mode was used. In addition, whether the inclusion of LA-M in the definition of reflux esophagitis affected the consistency of the diagnosis was investigated. METHODS: During upper endoscopy, endoscopic images of the gastroesophageal junction were taken using white light imaging (WLI), BLI-bright, and LCI modes. Four expert endoscopists and four trainees reviewed the images to diagnose reflux esophagitis according to the modified LA classification. RESULTS: The kappa values for the inter-observer variability for the diagnosis of reflux esophagitis were poor to fair among the experts (κ = â€Š0.22, 0.17, and 0.27 for WLI, BLI-bright, and LCI, respectively) and poor among the trainees (κ = â€Š0.18, 0.08, and 0.14 for WLI, BLI-bright, and LCI). The inter-observer variabilities for the diagnosis of reflux esophagitis excluding LA-M were fair to moderate (κ = â€Š0.42, 0.35, and 0.42 for WLI, BLI-bright, and LCI) among the expert endoscopists and moderate among the trainees (κ = 0.48, 0.43, and 0.51 for WLI, BLI-bright, and LCI). CONCLUSIONS: The inter-observer agreement for the diagnosis of reflux esophagitis was very low for both the expert endoscopists and the trainees, even using BLI-bright or LCI mode. However, when reflux esophagitis LA-M was excluded from the diagnosis of esophagitis, the degree of inter-observer agreement increased.

Transethnic analysis of the human leukocyte antigen region for ulcerative colitis reveals not only shared but also ethnicity-specific disease associations.

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gut. Genetic association studies have identified the highly variable human leukocyte antigen (HLA) region as the strongest susceptibility locus for IBD and specifically DRB1*01:03 as a determining factor for ulcerative colitis (UC). However, for most of the association signal such as delineation could not be made because of tight structures of linkage disequilibrium within the HLA. The aim of this study was therefore to further characterize the HLA signal using a transethnic approach. We performed a comprehensive fine mapping of single HLA alleles in UC in a cohort of 9272 individuals with African American, East Asian, Puerto Rican, Indian and Iranian descent and 40 691 previously analyzed Caucasians, additionally analyzing whole HLA haplotypes. We computationally characterized the binding of associated HLA alleles to human self-peptides and analyzed the physicochemical properties of the HLA proteins and predicted self-peptidomes. Highlighting alleles of the HLA-DRB1*15 group and their correlated HLA-DQ-DR haplotypes, we not only identified consistent associations (regarding effects directions/magnitudes) across different ethnicities but also identified population-specific signals (regarding differences in allele frequencies). We observed that DRB1*01:03 is mostly present in individuals of Western European descent and hardly present in non-Caucasian individuals. We found peptides predicted to bind to risk HLA alleles to be rich in positively charged amino acids. We conclude that the HLA plays an important role for UC susceptibility across different ethnicities. This research further implicates specific features of peptides that are predicted to bind risk and protective HLA proteins.

Comparative Efficacy of Various Stents for Palliation in Patients with Malignant Extrahepatic Biliary Obstruction: A Systematic Review and Network Meta-Analysis.

Although many studies have investigated the efficacy of stent placement for patients with malignant extrahepatic biliary obstruction, the clinical outcomes and adverse events of biliary stenting have not been comprehensively evaluated. We searched all relevant randomized-controlled trials that evaluated the comparative efficacy of biliary stents, including the plastic stents, uncovered self-expandable metal stents (SEMSs), and covered SEMSs in patients with malignant extrahepatic biliary obstructions. Twenty-one studies with 2326 patients were included. Both uncovered and covered SEMSs had a lower risk of recurrent biliary obstruction (RBO) compared to plastic stents (risk ratio (RR) (95% confidence interval [CI]): uncovered vs. plastic, 0.46 (0.35-0.62); covered vs. plastic, 0.46 (0.34-0.62)). A comparison of the groups using SEMSs revealed that tumor ingrowth was common in the uncovered SEMS group, while stent migration, tumor overgrowth, and occlusion by sludge were common in the covered SEMS group; however, the overall risk of RBO did not differ between these groups (RR (95% CI): uncovered vs. covered: 1.02 (0.80-1.30)). Although the main causes of RBO vary across stents, RBO risk was similar between uncovered and covered SEMS groups. Both SEMSs have superior efficacy in terms of RBO compared to plastic stents.

Comparison of the Diagnostic Performance of Novel Slim Biopsy Forceps with Conventional Biopsy Forceps for Biliary Stricture: A Multicenter Retrospective Study.

Novel slim biopsy forceps provide some technical advantages to facilitate a more accurate diagnosis, although we are not aware of any comparative studies. Therefore, we compared tissue acquisition and diagnostic accuracy between novel slim biopsy forceps and conventional biopsy forceps in cases with a biliary stricture. We reviewed 341 patients who underwent endoscopic retrograde cholangiopancreatography for the histological confirmation of biliary stricture at two tertiary hospitals between 2013 and 2020. The primary endpoint was the forceps' diagnostic accuracies. We included 276 patients who underwent biopsy using the novel forceps (n = 130) or conventional forceps (n = 146). The novel forceps provided 81.7% sensitivity, 100.0% specificity, positive-predictive value (PPV) of 100.0%, and negative-predictive value (NPV) of 57.8%, with an accuracy of 85.4% when the diagnosis by endobiliary biopsy included suspected or positive malignancy. The conventional forceps provided 61.7% sensitivity, 100.0% specificity, PPV of 100.0%, and NPV of 36.1%, with an accuracy of 68.5%. Only novel forceps use was significantly associated with an accurate diagnosis (odds ratio: 2.70, 95% confidence interval: 1.52-5.00). There were no significant inter-group differences in the procedure-related rates of adverse events. Endobiliary biopsy using novel forceps offered better diagnostic performance and more acceptable procedure-related adverse events than conventional forceps.

Effect of Nonsteroidal Anti-inflammatory Agents on Small Intestinal Injuries as Evaluated by Capsule Endoscopy.

BACKGROUND: Currently, because the population is aging, use of medications has been increasing, including use of nonsteroidal anti-inflammatory drugs (NSAIDs) and antithrombotic agents. AIMS: This study aims to investigate whether NSAIDs can cause damage to the small bowel (SB) mucosa. METHODS: Endoscopic videos of subjects who had undergone capsule endoscopy (CE) were evaluated by three experts in order to identify SB injury. All medications taken within 2 weeks from the time of CE were investigated. Cases with a final diagnosis of intestinal tuberculosis, inflammatory bowel disease, Behcet's disease, Peutz-Jeghers syndrome, small bowel lymphoma, or Henoch-Schönlein purpura were excluded from the analysis. RESULTS: Among the 273 subjects, 125 (45.8%) had SB erosions or ulcers (erosion group) and the remaining 148 (54.2%) did not (no erosion group). SB erosions or ulcers were more common in females, patients aged > 60 years, and subjects taking NSAIDs (p = 0.048, 0.032, and < 0.001, respectively). No statistically significant differences were found between the two groups in the following variables: history of cancer and GI surgery, reasons for the test, comorbidities, and use of anticoagulants and antiplatelet agents. Multivariate analysis showed that use of NSAIDs [OR 4.191 (95% CI 1.858-9.458), p < 0.001] was an independent risk factor for SB erosions or ulcers. CONCLUSIONS: Use of NSAIDs is the only independent risk factor for SB injury identified in this study. Antithrombotic agents do not cause or exacerbate damage to the SB, according to our results. CLINICAL TRIAL REGISTRATION: KCT0004795.

Diagnostic Accuracy of Fecal Calprotectin for the Detection of Small Bowel Crohn's Disease through Capsule Endoscopy: An Updated Meta-Analysis and Systematic Review.

Background/Aims: The diagnosis of small bowel Crohn's disease with negative ileocolonoscopic findings has been challenging. Fecal calprotectin (FC) has been used to detect colonic inflammation, but its efficacy for detecting small bowel inflammation is less established. We performed an updated meta-analysis to evaluate the diagnostic accuracy of FC to detect active small bowel inflammation observed during capsule endoscopy. Methods: We conducted a systematic literature search for studies that evaluated the correlation between small bowel inflammation and FC in patients with suspected/established Crohn's disease. We calculated the pooled sensitivity, specificity, and diagnostic odds ratios (DORs) and constructed hierarchical summary receiver operating characteristic curves for FC cutoffs of 50, 100, and 200 µg/g. Results: Fourteen studies were eligible for the final analysis. The DORs of all FC cutoffs were significant. The highest DOR was observed at 100 µg/g (sensitivity, 0.73; specificity, 0.73; and DOR, 7.89) and was suggested as the optimal diagnostic cutoff. If we analyzed only studies that included patients with suspected Crohn's disease, the DOR was 8.96. If we analyzed only studies that included patients with a Lewis score ≥135 as a diagnostic criterion for active disease, the DOR was 10.90. Conclusions: FC has significant diagnostic accuracy for detecting small bowel inflammation, and an FC cutoff of 100 µg/g can be used as a tool to screen for small bowel Crohn's disease.

The Protective Effect of 5-Aminosalicylic Acid Against Non-Steroidal Anti-Inflammatory Drug-Induced Injury Through Free Radical Scavenging in Small Intestinal Epithelial Cells.

Background and objectives: Non-steroidal anti-inflammatory drugs (NSAIDs) have been among the major causes of small intestinal injury in clinical practice. As such, the current study investigated the protective effect of 5-aminosalicylic acid (5-ASA) against an NSAID-induced small intestinal injury. Materials and Methods: IEC-6 cells were treated with various concentrations of indomethacin with or without 5-ASA in a serum-free medium, after which an 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Dromide (MTT) assay, a cell apoptosis assay, a caspase-3 activity assay, a reactive oxygen species (ROS) content and Superoxide dismutase 2 (SOD2) activity measurement, a Western blotting for occludin and zonula occludens-1 (ZO-1) and a wound healing assay were conducted. Results: 5-ASA ameliorated indomethacin-induced cell apoptosis and an increase in the intracellular ROS content while augmenting the indomethacin-induced suppression of SOD2 activity in IEC-6 cells. Moreover, 5-ASA reversed the indomethacin-induced attenuation of occludin and ZO-1 expression and promoted faster wound healing effects in IEC-6 cells following an indomethacin-induced injury. Conclusion: Our results suggested that 5-ASA protects small intestinal cells against an NSAID-induced small intestinal injury by scavenging free radicals. Therefore, 5-ASA could be a potential treatment for an NSAID-induced small intestinal injury.

Genotype-based Treatment With Thiopurine Reduces Incidence of Myelosuppression in Patients With Inflammatory Bowel Diseases.

BACKGROUND & AIMS: Thiopurine-related myelosuppression (most frequently leukopenia) interferes with thiopurine therapy for patients with inflammatory bowel diseases (IBD). We investigated whether pretreatment analyses genetic variants associated with thiopurine-induced leukopenia could be used to effectively identify patients who required dose adjustments. METHODS: We performed a multicenter, prospective study of patients with IBD at 5 tertiary medical centers in Korea, from January 2016 through September 2018. Seventy-two patients were randomly assigned to a group that underwent genotype analysis for the NUDT15 variant (rs116855232) and FTO variant (rs79206939) and 3 common TPMT variants (rs1800460, rs1800462, rs1142345) associated with myelosuppression and 92 patients were assigned to a group that did not undergo genotype analysis (non-genotyping group). Patients heterozygous for any variant received 50 mg azathioprine equivalents, whereas those who were homozygous for any variant received alternative drugs. Patients who did not carry any of the genetic variants and patients in the non-genotyping group received 50 mg azathioprine equivalents followed by dose escalation up to 2-2.5 mg/kg. Myelosuppression was defined as white blood cell counts below 3000/µL, levels of hemoglobin 10 g/dL, or platelet counts below 100 K/µL. RESULTS: Twelve patients (16.7%) in the genotype analysis group and 33 patients (35.9%) in the non-genotyping group developed myelosuppression (P=.005). A multivariate analysis revealed that body mass indices above 21 kg/m2 (hazard ratio [HR], 0.43; 95% CI, 0.22-0.81; P = .009), pretreatment genotype analysis (HR, 0.37; 95% CI, 0.18-0.77; P = .008), and the maximum dose of thiopurines (HR, 0.34; 95% CI, 0.19-0.59; P < .001) independently decreased risk of myelosuppression. Pretreatment genotype analysis reduced numbers of outpatient clinic visit and numbers of patients with drug discontinuation or dose reductions. CONCLUSIONS: In a randomized controlled study of patients undergoing thiopurine therapy for IBD, we found that selection of therapy based on genetic variants associated with thiopurine-induced leukopenia significantly reduced the proportion of patients with myelosuppression during treatment. ClinicalTrials.gov no: NCT03719118.

Protein-coding variants contribute to the risk of atopic dermatitis and skin-specific gene expression.

BACKGROUND: Fifteen percent of atopic dermatitis (AD) liability-scale heritability could be attributed to 31 susceptibility loci identified by using genome-wide association studies, with only 3 of them (IL13, IL-6 receptor [IL6R], and filaggrin [FLG]) resolved to protein-coding variants. OBJECTIVE: We examined whether a significant portion of unexplained AD heritability is further explained by low-frequency and rare variants in the gene-coding sequence. METHODS: We evaluated common, low-frequency, and rare protein-coding variants using exome chip and replication genotype data of 15,574 patients and 377,839 control subjects combined with whole-transcriptome data on lesional, nonlesional, and healthy skin samples of 27 patients and 38 control subjects. RESULTS: An additional 12.56% (SE, 0.74%) of AD heritability is explained by rare protein-coding variation. We identified docking protein 2 (DOK2) and CD200 receptor 1 (CD200R1) as novel genome-wide significant susceptibility genes. Rare coding variants associated with AD are further enriched in 5 genes (IL-4 receptor [IL4R], IL13, Janus kinase 1 [JAK1], JAK2, and tyrosine kinase 2 [TYK2]) of the IL13 pathway, all of which are targets for novel systemic AD therapeutics. Multiomics-based network and RNA sequencing analysis revealed DOK2 as a central hub interacting with, among others, CD200R1, IL6R, and signal transducer and activator of transcription 3 (STAT3). Multitissue gene expression profile analysis for 53 tissue types from the Genotype-Tissue Expression project showed that disease-associated protein-coding variants exert their greatest effect in skin tissues. CONCLUSION: Our discoveries highlight a major role of rare coding variants in AD acting independently of common variants. Further extensive functional studies are required to detect all potential causal variants and to specify the contribution of the novel susceptibility genes DOK2 and CD200R1 to overall disease susceptibility.

ZNF133 is associated with infliximab responsiveness in patients with inflammatory bowel diseases.

BACKGROUND AND AIM: Infliximab has been widely prescribed for treating inflammatory bowel disease (IBD). However, the response rates to infliximab differ among patients. Therefore, we aimed to identify the genetic and clinical markers that predict infliximab response. METHODS: A total of 139 Korean patients with IBD who received infliximab were classified according to infliximab response as follows: (i) primary response vs nonresponse and (ii) sustained response vs loss of response. We performed an association study using whole-exome sequencing data to identify genetic variants associated with infliximab response. Candidate variants were validated in 77 German patients with IBD. Stepwise multivariate logistic regression was performed to identify predictors. RESULTS: We found five candidate variants that were associated with primary nonresponse to infliximab (P < 5 × 10-6 ). Of the five variants, rs2228273 in ZNF133 was validated in German (combined P = 6.49 × 10-7 ). We also identified the best genetic variant (rs9144, P = 4.60 × 10-6 ) associated with the loss of infliximab response. In multivariate regression analysis, rs2228273 (P = 2.10 × 10-5 ), concurrent azathioprine/6-mercaptopurine use, and bodyweight at the first infliximab use (< 50 kg) were associated with primary nonresponse. In addition, the Crohn's disease activity index at the first infliximab use and rs9144 (P = 0.001) were independently associated with the loss of response in patients with Crohn's disease. CONCLUSIONS: We identified clinical and genetic markers associated with infliximab response in IBD patients. Our findings could provide insights to maximize the efficacy of infliximab therapy in IBD patients.

Construction and benchmarking of a multi-ethnic reference panel for the imputation of HLA class I and II alleles.

Genotype imputation of the human leukocyte antigen (HLA) region is a cost-effective means to infer classical HLA alleles from inexpensive and dense SNP array data. In the research setting, imputation helps avoid costs for wet lab-based HLA typing and thus renders association analyses of the HLA in large cohorts feasible. Yet, most HLA imputation reference panels target Caucasian ethnicities and multi-ethnic panels are scarce. We compiled a high-quality multi-ethnic reference panel based on genotypes measured with Illumina's Immunochip genotyping array and HLA types established using a high-resolution next generation sequencing approach. Our reference panel includes more than 1,300 samples from Germany, Malta, China, India, Iran, Japan and Korea and samples of African American ancestry for all classical HLA class I and II alleles including HLA-DRB3/4/5. Applying extensive cross-validation, we benchmarked the imputation using the HLA imputation tool HIBAG, our multi-ethnic reference and an independent, previously published data set compiled of subpopulations of the 1000 Genomes project. We achieved average imputation accuracies higher than 0.924 for the commonly studied HLA-A, -B, -C, -DQB1 and -DRB1 genes across all ethnicities. We investigated allele-specific imputation challenges in regard to geographic origin of the samples using sensitivity and specificity measurements as well as allele frequencies and identified HLA alleles that are challenging to impute for each of the populations separately. In conclusion, our new multi-ethnic reference data set allows for high resolution HLA imputation of genotypes at all classical HLA class I and II genes including the HLA-DRB3/4/5 loci based on diverse ancestry populations.

Compound heterozygous mutations in IL10RA combined with a complement factor properdin mutation in infantile-onset inflammatory bowel disease.

OBJECTIVES: Inflammatory bowel diseases (IBDs) are chronic and multifactorial diseases resulting from a complex interaction of host genetic factors and environmental stimuli. Although many genome-wide association studies have identified host genetic factors associated with IBD, rare Mendelian forms of IBD have been reported in patients with very early onset forms. Therefore, this study aimed to identify genetic variants associated with infantile-onset IBD. PARTICIPANTS AND METHODS: We obtained genomic DNA from whole blood samples of a male patient with infantile-onset IBD and nonconsanguineous Korean parents. Whole-exome sequencing was performed using trio samples. Then, we analyzed the data using susceptibility genes for monogenic forms of IBD and various immunodeficiencies and protein structural analysis. RESULTS: The patient who presented with oral aphthous ulcers at the age of 14 days suffered from severe colitis and was refractory to medical treatment. Compound heterozygous mutations in IL10RA (p.R101W; p.T179T) were found in the patient. In addition, a hemizygous mutation in complement factor properdin (CFP) (p.L456V) located on the X-chromosome was detected, inherited from the patient's mother. Protein structural modeling suggested impaired properdin subunit interactions by p.L456V that may hamper protein oligomerization required for complement activation. CONCLUSION: This study identified compound heterozygous mutations in IL10RA combined with a hemizygous CFP mutation in infantile-onset IBD by using whole-exome sequencing. CFP p.L456V may exacerbate symptoms of infantile-onset IBD by disturbing oligomerization of properdin.

Association study between OCTN1 functional haplotypes and Crohn's disease in a Korean population.

Crohn's disease (CD) is a chronic inflammatory bowel disease with multifactorial causes including environmental and genetic factors. Several studies have demonstrated that the organic cation/carnitine transporter 1 (OCTN1) non-synonymous variant L503F is associated with susceptibility to CD. However, it was reported that L503F is absent in Asian populations. Previously, we identified and functionally characterized genetic variants of the OCTN1 promoter region in Koreans. In that study, four variants demonstrated significant changes in promoter activity. In the present study, we determined whether four functional variants of the OCTN1 promoter play a role in the susceptibility to or clinical course of CD in Koreans. To examine it, the frequencies of the four variants of the OCTN1 promoter were determined by genotyping using DNA samples from 194 patients with CD and 287 healthy controls. Then, associations between genetic variants and the susceptibility to CD or clinical course of CD were evaluated. We found that susceptibility to CD was not associated with OCTN1 functional promoter variants or haplotypes showing altered promoter activities in in vitro assays. However, OCTN1 functional promoter haplotypes showing decreased promoter activities were significantly associated with a penetrating behavior in CD patients (HR=2.428, p=0.009). Our results suggest that the OCTN1 functional promoter haplotypes can influence the CD phenotype, although these might not be associated with susceptibility to this disease.

A coding variant in FTO confers susceptibility to thiopurine-induced leukopenia in East Asian patients with IBD.

OBJECTIVE: Myelosuppression is a life-threatening complication of thiopurine therapy, and the incidence of thiopurine-induced myelosuppression is higher in East Asians than in Europeans. We investigated genetic factors associated with thiopurine-induced leukopenia in patients with IBD. DESIGN: A genome-wide association study (GWAS) was conducted in thiopurine-treated patients with IBD, followed by high-throughput sequencing of genes identified as significant in the GWAS or those involved in thiopurine metabolism (n=331). Significant loci associated with thiopurine-induced leukopenia were validated in two additional replication cohorts (n=437 and n=330). Functional consequences of FTO (fat mass and obesity-associated) variant were examined both in vitro and in vivo. RESULTS: The GWAS identified two loci associated with thiopurine-induced leukopenia (rs16957920, FTO intron; rs2834826, RUNX1 intergenic). High-throughput targeted sequencing indicated that an FTO coding variant (rs79206939, p.A134T) linked to rs16957920 is associated with thiopurine-induced leukopenia. This result was further validated in two replication cohorts (combined p=1.3×10-8, OR=4.3). The frequency of FTO p.A134T is 5.1% in Koreans but less than 0.1% in Western populations. The p.A134T variation reduced FTO activity by 65% in the nucleotide demethylase assay. In vivo experiments revealed that Fto-/- and Fto+/- mice were more susceptible to thiopurine-induced myelosuppression than wild-type mice. CONCLUSIONS: The results suggest that the hypomorphic FTO p.A134T variant is associated with thiopurine-induced leukopenia. These results shed light on the novel physiological role of FTO and provide a potential pharmacogenetic biomarker for thiopurine therapy.

Identification of OCTN2 variants and their association with phenotypes of Crohn's disease in a Korean population.

Crohn's disease (CD) is a chronic inflammatory bowel disease and a genetic variant in the OCTN2, g.-207G > C is significantly associated with CD susceptibility. This study was aimed to identify novel OCTN2 functional promoter variants and their roles in transcriptional regulation using various in vitro assays. In addition, we investigated the association between OCTN2 genotypes and CD through genetic analysis using DNA samples from 193 patients with CD and 281 healthy controls. Among the three major promoter haplotypes of OCTN2 identified, one haplotype, H3, showed a significant decrease in promoter activity: two polymorphisms in H3 were associated with a significant reduction in promoter activity. In particular, we found that the reduced transcriptional activity of those two polymorphisms results from a reduction in the binding affinity of the activators, NF-E2 and YY1, to the OCTN2 promoter. The functional haplotype of the OCTN2 promoter was associated with clinical course of CD such as the disease behavior and need for surgery. However, genetic variants or haplotypes of OCTN2 did not affect the susceptibility to CD. Our results suggest that a common promoter haplotype of OCTN2 regulates the transcriptional rate of OCTN2 and influences the clinical course of CD.

HLA-C*01 is a Risk Factor for Crohn's Disease.

BACKGROUND: A dysregulated mucosal immune response to the intestinal environment in a genetically susceptible host is hypothesized to be critical to the pathogenesis of Crohn's disease (CD). Therefore, we examined CD-susceptibility genes involved in the immune response through a genome-wide association study and consecutive genotyping of human leukocyte antigens (HLAs) and killer cell immunoglobulin-like receptors. METHODS: An initial genome-wide association study was performed with 275 CD patients and 2369 controls from a Korean population. To validate the loci identified in the genome-wide association study, replication genotyping was performed in a different cohort of 242 CD patients and 1066 controls. Finally, high-resolution genotyping of HLA and killer cell immunoglobulin-like receptor was performed. RESULTS: Four susceptibility loci, a promoter region in tumor necrosis factor (ligand) superfamily member (TNFSF15) and 3 independent regions in HLAs, showed significant associations with CD. Among them, rs114985235 in the intergenic region between HLA-B and HLA-C showed the strongest association, with an increased risk of CD (P = 8.71 × 10; odds ratio, 2.25). HLA typing in this region showed HLA-C*01 to be responsible for the association of CD among 43 HLA-B and HLA-C genotypes identified in the Korean population. However, the interaction of HLA-C with killer cell immunoglobulin-like receptor had little effect on the development of CD. CONCLUSIONS: We newly identified HLA-C*01 as a prominent CD-susceptibility HLA allotype in the Korean population. In addition, these results confirm that genetic variations in immune response genes, such as HLAs and TNFSF15, are important host factors for the pathogenesis of CD.