Sven Almer

Association of NOD2 leucine-rich repeat variants with susceptibility to Crohn's disease

Crohns disease and ulcerative colitis, the two main types of chronic inflammatory bowel disease, are multifactorial conditions of unknown aetiology. A susceptibility locus for Crohns disease has been mapped to chromosome 16. Here we have used a positional-cloning strategy, based on linkage analysis followed by linkage disequilibrium mapping, to identify three independent associations for Crohns disease: a frameshift variant and two missense variants of NOD2, encoding a member of the Apaf-1/Ced-4 superfamily of apoptosis regulators that is expressed in monocytes. These NOD2 variants alter the structure of either the leucine-rich repeat domain of the protein or the adjacent region. NOD2 activates nuclear factor NF-kB; this activating function is regulated by the carboxy-terminal leucine-rich repeat domain, which has an inhibitory role and also acts as an intracellular receptor for components of microbial pathogens. These observations suggest that the NOD2 gene product confers susceptibility to Crohns disease by altering the recognition of these components and/or by over-activating NF-kB in monocytes, thus documenting a molecular model for the pathogenic mechanism of Crohns disease that can now be further investigated.

CARD15/NOD2 Mutational Analysis and Genotype-Phenotype Correlation in 612 Patients with Inflammatory Bowel Disease

CARD15/NOD2 encodes a protein involved in bacterial recognition by monocytes. Mutations in CARD15 have recently been found in patients with Crohn disease (CD), a chronic inflammatory condition of the digestive tract. Here, we report the mutational analyses of CARD15 in 453 patients with CD, including 166 sporadic and 287 familial cases, 159 patients with ulcerative colitis (UC), and 103 healthy control subjects. Of 67 sequence variations identified, 9 had an allele frequency >5% in patients with CD. Six of them were considered to be polymorphisms, and three (R702W, G908R, and 1007fs) were confirmed to be independently associated with susceptibility to CD. Also considered as potential disease-causing mutations (DCMs) were 27 rare additional mutations. The three main variants (R702W, G908R, and 1007fs) represented 32%, 18%, and 31%, respectively, of the total CD mutations, whereas the total of the 27 rare mutations represented 19% of DCMs. Altogether, 93% of the mutations were located in the distal third of the gene. No mutations were found to be associated with UC. In contrast, 50% of patients with CD carried at least one DCM, including 17% who had a double mutation. This observation confirmed the gene-dosage effect in CD. The patients with double-dose mutations were characterized by a younger age at onset (16.9 years vs. 19.8 years; P=.01), a more frequent stricturing phenotype (53% vs. 28%; P=.00003; odds ratio 2.92), and a less frequent colonic involvement (43% vs. 62%; P=.003; odds ratio 0.44) than were seen in those patients who had no mutation. The severity of the disease and extraintestinal manifestations were not different for any of the CARD15 genotypes. The proportion of familial and sporadic cases and the proportion of patients with smoking habits were similar in the groups of patients with CD with or without mutation. These findings provide tools for a DNA-based test of susceptibility and for genetic counseling in inflammatory bowel disease.

Hepatic and extrahepatic malignancies in primary sclerosing cholangitis

BACKGROUND/AIMS To assess the risk of hepatic and extrahepatic malignancies in a large cohort of Swedish primary sclerosing cholangitis (PSC) patients compared with that of the general Swedish population. METHODS The study cohort comprised 604 PSC patients identified between 1970 and 1998. Follow-up was provided through linkages to the Swedish Cancer and Death registries. Cumulative incidence of malignancies and standard incidence ratio were calculated with the incidence rates in the Swedish population, taking into account: sex, age and calendar year as comparison group. RESULTS Median time of follow-up was 5.7 years (range 0-27.8). Seventy-nine percent had concomitant inflammatory bowel disease. The cause of death was cancer in 44%. The frequency of hepatobiliary malignancies was 13.3% (81/604). Thirty-seven percent (30/81) of all hepatobiliary malignancies were diagnosed less than 1 year after the diagnosis of PSC. The risk for hepatobiliary malignancy was increased 161 times, for colorectal carcinoma 10 times and for pancreatic carcinoma 14 times, compared with that of the general population. CONCLUSIONS In this national-based study including the largest cohort of PSC patients ever presented, the frequency of cholangiocarcinoma is 13%. The risk of hepatobiliary carcinoma is constant after the first year after PSC diagnosis with an incidence rate of 1.5% per year. The risk of pancreatic carcinoma is increased 14 times compared with the general Swedish population. These results are suggestive of an increased risk of pancreatic carcinoma in patients with PSC.

3rd European Evidence-based Consensus on the Diagnosis and Management of Crohn’s Disease 2016: Part 1: Diagnosis and Medical Management

This paper is the first in a series of two publications relating to the European Crohn’s and Colitis Organisation [ECCO] evidence-based consensus on the diagnosis and management of Crohn’s disease and concerns the methodology of the consensus process, and the classification, diagnosis and medical management of active and quiescent Crohn’s disease. Surgical management as well as special situations including management of perianal Crohn’s disease of this ECCO Consensus are covered in a subsequent second paper [Gionchetti et al JCC 2016].

East–West gradient in the incidence of inflammatory bowel disease in Europe: the ECCO-EpiCom inception cohort

Objective The incidence of inflammatory bowel disease (IBD) is increasing in Eastern Europe. The reasons for these changes remain unknown. The aim of this study was to investigate whether an East–West gradient in the incidence of IBD in Europe exists. Design A prospective, uniformly diagnosed, population based inception cohort of IBD patients in 31 centres from 14 Western and eight Eastern European countries covering a total background population of approximately 10.1 million people was created. One-third of the centres had previous experience with inception cohorts. Patients were entered into a low cost, web based epidemiological database, making participation possible regardless of socioeconomic status and prior experience. Results 1515 patients aged 15 years or older were included, of whom 535 (35%) were diagnosed with Crohns disease (CD), 813 (54%) with ulcerative colitis (UC) and 167 (11%) with IBD unclassified (IBDU). The overall incidence rate ratios in all Western European centres were 1.9 (95% CI 1.5 to 2.4) for CD and 2.1 (95% CI 1.8 to 2.6) for UC compared with Eastern European centres. The median crude annual incidence rates per 100 000 in 2010 for CD were 6.5 (range 0–10.7) in Western European centres and 3.1 (range 0.4–11.5) in Eastern European centres, for UC 10.8 (range 2.9–31.5) and 4.1 (range 2.4–10.3), respectively, and for IBDU 1.9 (range 0–39.4) and 0 (range 0–1.2), respectively. In Western Europe, 92% of CD, 78% of UC and 74% of IBDU patients had a colonoscopy performed as the diagnostic procedure compared with 90%, 100% and 96%, respectively, in Eastern Europe. 8% of CD and 1% of UC patients in both regions underwent surgery within the first 3 months of the onset of disease. 7% of CD patients and 3% of UC patients from Western Europe received biological treatment as rescue therapy. Of all European CD patients, 20% received only 5-aminosalicylates as induction therapy. Conclusions An East–West gradient in IBD incidence exists in Europe. Among this inception cohort—including indolent and aggressive cases—international guidelines for diagnosis and initial treatment are not being followed uniformly by physicians.

Pharmacogenetics during standardised initiation of thiopurine treatment in inflammatory bowel disease

Background: Firm recommendations about the way thiopurine drugs are introduced and the use of thiopurine methyltransferase (TPMT) and metabolite measurements during treatment in inflammatory bowel disease (IBD) are lacking. Aim: To evaluate pharmacokinetics and tolerance after initiation of thiopurine treatment with a fixed dosing schedule in patients with IBD. Patients: 60 consecutive patients with Crohn’s disease (n = 33) or ulcerative colitis (n = 27) were included in a 20 week open, prospective study. Methods: Thiopurine treatment was introduced using a predefined dose escalation schedule, reaching a daily target dose at week 3 of 2.5 mg azathioprine or 1.25 mg 6-mercaptopurine per kg body weight. TPMT and ITPA genotypes, TPMT activity, TPMT gene expression, and thiopurine metabolites were determined. Clinical outcome and occurrence of adverse events were monitored. Results: 27 patients completed the study per protocol, while 33 were withdrawn (early protocol violation (n = 5), TPMT deficiency (n = 1), thiopurine related adverse events (n = 27)); 67% of patients with adverse events tolerated long term treatment on a lower dose (median 1.32 mg azathioprine/kg body weight). TPMT activity did not change during the 20 week course of the study but a significant decrease in TPMT gene expression was found (TPMT/huCYC ratio; p = 0.02). Patients with meTIMP concentrations >11 450 pmol/8×108 red blood cells during steady state at week 5 had an increased risk of developing myelotoxicity (odds ratio = 45.0; p = 0.015). Conclusions: After initiation of thiopurine treatment using a fixed dosing schedule, no general induction of TPMT enzyme activity occurred, though TPMT gene expression decreased. The development of different types of toxicity was unpredictable, but we found that measurement of meTIMP early in the steady state phase helped to identify patients at risk of developing myelotoxicity.

Resequencing of positional candidates identifies low frequency IL23R coding variants protecting against inflammatory bowel disease

Genome-wide association studies (GWAS) have identified dozens of risk loci for many complex disorders, including Crohns disease. However, common disease-associated SNPs explain at most ∼20% of the genetic variance for Crohns disease. Several factors may account for this unexplained heritability, including rare risk variants not adequately tagged thus far in GWAS. That rare susceptibility variants indeed contribute to variation in multifactorial phenotypes has been demonstrated for colorectal cancer, plasma high-density lipoprotein cholesterol levels, blood pressure, type 1 diabetes, hypertriglyceridemia and, in the case of Crohns disease, for NOD2 (refs. 14,15). Here we describe the use of high-throughput resequencing of DNA pools to search for rare coding variants influencing susceptibility to Crohns disease in 63 GWAS-identified positional candidate genes. We identify low frequency coding variants conferring protection against inflammatory bowel disease in IL23R, but we conclude that rare coding variants in positional candidates do not make a large contribution to inherited predisposition to Crohns disease.

The AST/ALT ratio as an indicator of cirrhosis in patients with PBC

Abstract: Objectives: A non‐invasive, simple and non‐expensive test to predict cirrhosis would be highly desirable. The aspartate aminotransferase/alanine aminotransferase (AST/ALT) ratio has been proven to be such an indicator of cirrhosis in alcoholic liver disease, hepatitis C.

Adverse events leading to modification of therapy in a large cohort of patients with inflammatory bowel disease.

Adverse events leading to discontinuation or dose reduction of thiopurine therapy occur in 9–28% of patients with inflammatory bowel disease.

Increased risk of primary sclerosing cholangitis and ulcerative colitis in first-degree relatives of patients with primary sclerosing cholangitis

BACKGROUND & AIMS The importance of genetic factors for the development of primary sclerosing cholangitis (PSC) is incompletely understood. This study assessed the risk of PSC and inflammatory bowel disease (IBD) among first-degree relatives of patients with PSC, compared with the first-degree relatives of a cohort without PSC. METHODS Subjects from the national Swedish cohort of PSC patients (n = 678) were matched for date of birth, sex, and region to up to 10 subjects without a diagnosis of PSC (n = 6347). Linkage through general population registers identified first-degree relatives of subjects in both the PSC and comparison cohorts (n = 34,092). Diagnoses among first-degree relatives were identified by using the Inpatient Register. RESULTS The risk of cholangitis was statistically significantly increased in offspring, siblings, and parents of the PSC patient cohort, compared with relatives of the comparison cohort, with the hazard ratios and 95% confidence intervals, 11.5 (1.6-84.4), 11.1 (3.3-37.8), and 2.3 (0.9-6.1), respectively. The hazard ratios for ulcerative colitis (UC) among first-degree relatives of all PSC patients was 3.3 (2.3-4.9) and for Crohns disease 1.4 (0.8-2.5). The risk of UC for relatives of PSC patients without IBD was also increased, 7.4 (2.9-18.9). CONCLUSIONS First-degree relatives of patients with PSC run an increased risk of PSC, indicating the importance of genetic factors in the etiology of PSC. First-degree relatives of PSC patients without IBD are also at an increased risk of UC, which might indicate shared genetic susceptibility factors for PSC and UC.