J E Lennard-Jones

Association between insertion mutation in NOD2 gene and Crohn's disease in German and British populations

Background Genetic predisposition to inflammatory bowel disease (IBD) has been shown by epidemiological and linkage studies. Genetic linkage of IBD to chromosome 16 has been previously observed and replicated in independent populations. The recently identified NOD2 gene is a good positional and functional candidate gene since it is located in the region of linkage on chromosome 16q12, and activates nuclear factor (NF) kappaB in response to bacterial lipopolysaccharides. Methods We sequenced the coding region of the NOD2 gene and genotyped an insertion polymorphism affecting the leucine-rich region of the protein product in 512 individuals with IBD from 309 German or British families, 369 German trios (ie, German patients with sporadic IBD and their unaffected parents), and 272 normal controls. We then tested for association with Crohns disease and ulcerative colitis. Findings Family-based association analyses were consistently positive in 95 British and 99 German affected sibling pairs with Crohns disease (combined p<0.0001); the association was confirmed in the 304 German trios with Crohns disease. No association was seen in the 115 sibling pairs and 65 trios with ulcerative colitis. The genotype-specific disease risks conferred by heterozygous and homozygous mutant genotypes were 2.6 (95% CI 1.5-4.5) and 42.1 (4.3-infinity), respectively. Interpretation The insertion mutation in the NOD2 gene confers a substantially increased susceptibility to Crohns disease but not to ulcerative colitis.

Long-term neoplasia risk after azathioprine treatment in inflammatory bowel disease

The incidence of various cancers, especially non-Hodgkin lymphoma (NHL), is higher among patients who receive azathioprine for immunosuppression after organ transplants than in the general population. We have studied the risk of neoplasia after azathioprine in 755 patients treated for inflammatory bowel disease. The patients received 2 mg/kg daily for a median of 12.5 months (range 2 days to 15 years) between 1962 and 1991; median follow-up was 9 years (range 2 weeks to 29 years). Overall there was no significant excess of cancer: 31 azathioprine-treated patients developed cancer before age 85 compared with 24.3 expected from rates in the general population (observed/expected ratio 1.27, p = 0.186). There was a difference in the frequency of colorectal (13) and anal (2) carcinomas (expected 2.27; ratio 6.7, p = 0.00001); these tumours are recognised complications of chronic inflammatory bowel disease. There were 2 cases of invasive cervical cancer (expected 0.5), but no case of NHL. Among patients with extensive chronic ulcerative colitis there was no difference in cancer frequency between 86 who had received azathioprine and 180 matched patients who had never received it. Thus, azathioprine treatment does not substantially increase the risk of cancer in inflammatory bowel disease.

Bone marrow toxicity caused by azathioprine in inflammatory bowel disease: 27 years of experience.

Myelosuppression is an important and potentially lethal complication of azathioprine treatment. The blood count has been reviewed in all patients treated with azathioprine for inflammatory bowel disease over 27 years in one hospital. Altogether 739 patients (422 with Crohns disease, 284 with ulcerative colitis, and 33 with indeterminate colitis) were treated with 2 mg/kg/day azathioprine for a median of 12.5 months (range 0.5-132) between 1964 and 1991. Full blood counts were performed monthly for the duration of treatment. In 37 patients (5%) who developed bone marrow toxicity, the drug was withdrawn or the dose reduced. Thirty two of these patients were asymptomatic and five developed symptoms. Leucopenia (white blood count less than 3.0 x 10g/l) occurred in 28 (3.8%) patients, in nine of whom it was severe (white blood count < 2.0 x 10(9)/l). Of these nine patients, three were pancytopenic: two died from sepsis and the other had pneumonia but recovered. A further two patients with severe leucopenia developed a mild upper respiratory infection only. Thrombocytopenia (platelet count < 100,000 x 10(6)/l) in 15 patients was associated with leucopenia in six and developed in isolation in a further nine (total 2%). Isolated thrombocytopenia was never clinically severe. Myelotoxicity from azathioprine developed at any time during drug treatment (range 2 weeks-11 years after starting the drug) and occurred either suddenly or over several months. Bone marrow suppression as a result of azathioprine treatment is uncommon when a moderate dose is used, but is potentially severe. Leucopenia is the commonest and most important haematological complication. Regular monitoring of the full blood count is recommended during treatment.

Factors affecting the outcome of endoscopic surveillance for cancer in ulcerative colitis

BACKGROUND/AIMS Cancer surveillance in patients with ulcerative colitis is of unproven benefit. This study assesses the efficacy and analyzes factors limiting the success of a surveillance program during a 21-year period in 332 patients with ulcerative colitis to the hepatic flexure and disease duration exceeding 10 years. METHODS Clinical assessment and sigmoidoscopy with biopsy was undertaken yearly. Colonoscopy and biopsy every 10 cm throughout the colon was performed every 2 years or more often if dysplasia was found. Only biopsy specimens reported as showing dysplasia were reviewed. RESULTS Surveillance contributed to detection of 11 symptomless carcinomas (8 Dukes A, 1 Dukes B, and 2 Dukes C), but 6 symptomatic tumors (4 Dukes C and 2 disseminated) presented 10-43 months after a negative colonoscopy. Dysplasia without carcinoma was confirmed in 12 symptomless patients who underwent colectomy. The 5-year predictive value of low-grade dysplasia for either cancer or high-grade dysplasia was 54% using current criteria. CONCLUSIONS Surveillance identified some patients at a curable stage of cancer or with dysplasia. Limiting factors were failure to include patients with presumed distal colitis, biennial colonoscopy, the number of biopsy specimens at each colonoscopy, and variation in histological identification and grading of dysplasia.

Precancer and cancer in extensive ulcerative colitis: findings among 401 patients over 22 years.

Patients with extensive ulcerative colitis who do not need early surgery have been offered regular examination with the aim of detecting precancerous change (dysplasia) or early colorectal carcinoma. Outpatient visits with clinical examination, sigmoidoscopy, and biopsy were supplemented by two-yearly colonoscopy after the disease course reached 10 years. During the 22 year period from the beginning of 1966 to the end of 1987, 401 patients entered the programme and together contributed 4048 patient-years of observation. Apart from nine patients who left the country, follow up is complete until 1986 or 1987. Colorectal carcinoma developed in 22 patients and, in a further 12, biopsy evidence of precancer, described as severe/high grade dysplasia, was confirmed in a colectomy specimen. The cumulative probability of developing carcinoma was 3% at 15 years, 5% at 20 years, and 9% at 25 years; corresponding figures for precancer or carcinoma, or both were 4%, 7%, and 13%. Five patients died of colorectal carcinoma, two while under regular observation and three after developing carcinoma four to six years after their last attendance. Among the 17 patients who developed carcinoma while under observation, the Dukes stage was A or B in 12. Patients with extensive colitis whose disability does not warrant early surgery have a clinically important cancer risk after the disease has been present for 10 years. Our results suggest that follow up in the manner described reduces the mortality from this complication. Further work is needed to define the optimum method of surveillance and show if it is cost effective.

A genomewide analysis provides evidence for novel linkages in inflammatory bowel disease in a large european cohort

Inflammatory bowel disease (IBD) is characterized by a chronic relapsing intestinal inflammation, typically starting in early adulthood. IBD is subdivided into two subtypes, on the basis of clinical and histologic features: Crohn disease and ulcerative colitis (UC). Previous genomewide searches identified regions harboring susceptibility loci on chromosomes 1, 3, 4, 7, 12, and 16. To expand our understanding of the genetic risk profile, we performed a 9-cM genomewide search for susceptibility loci in 268 families containing 353 affected sibling pairs. Previous linkages on chromosomes 12 and 16 were replicated, and the chromosome 4 linkage was extended in this sample. New suggestive evidence for autosomal linkages was observed on chromosomes 1, 6, 10, and 22, with LOD scores of 2.08, 2.07, 2.30, and 1.52, respectively. A maximum LOD score of 1.76 was observed on the X chromosome, for UC, which is consistent with the clinical association of IBD with Ullrich-Turner syndrome. The linkage finding on chromosome 6p is of interest, given the possible contribution of human leukocyte antigen and tumor necrosis-factor genes in IBD. This genomewide linkage scan, done with a large family cohort, has confirmed three previous IBD linkages and has provided evidence for five additional regions that may harbor IBD predisposition genes.

Colonic preservation reduces need for parenteral therapy, increases incidence of renal stones, but does not change high prevalence of gall stones in patients with a short bowel.

Forty six patients with less than 200 cm of normal jejunum and no functioning colon were compared with 38 patients with similar jejunal lengths in continuity with a functioning colon. Women predominated (67%), and the most common diagnosis in each group was Crohns disease (33 of 46 no colon, 16 of 38 with colon). All patients without a colon and less than 85 cm of jejunum and all those with a colon and less than 45 cm jejunum needed long term parenteral nutrition. Six months after the last resection 12 of 17 patients with less than 100 cm jejunum and no colon needed intravenous supplements compared with 7 of 21 with a colon. Between 6 months and 2 years, little change occurred in the nutritional/fluid requirements in either group, though there was weight gain. Of 71 patients assessed clinically at a median of 5 years, none with more than 50 cm of jejunum and a colon needed parenteral supplements. Most (25 of 27) of those without a colon who did not need parenteral supplements required oral electrolyte replacement compared with few (4 of 27) with a colon. None of the patients without a colon developed symptomatic renal stones compared with 9 of 38 (24%) with a colon (p < 0.001). Stone analysis in three patients showed calcium oxalate. Gall stone prevalence was high but equal in the two groups--43% of those without and 44% of those with a colon.

Linkage of Inflammatory Bowel Disease to Human Chromosome 6p

Inflammatory bowel disease (IBD) is characterized by a chronic relapsing intestinal inflammation. IBD is subdivided into Crohn disease and ulcerative colitis phenotypes. Given the immunologic dysregulation in IBD, the human-leukocyte-antigen region on chromosome 6p is of significant interest. Previous association and linkage analysis has provided conflicting evidence as to the existence of an IBD-susceptibility locus in this region. Here we report on a two-stage linkage and association analysis of both a basic population of 353 affected sibling pairs (ASPs) and an extension of this population to 428 white ASPs of northern European extraction. Twenty-eight microsatellite markers on chromosome 6 were genotyped. A peak multipoint LOD score of 4.2 was observed, at D6S461, for the IBD phenotype. A transmission/disequilibrium test (TDT) result of P=.006 was detected for D6S426 in the basic population and was confirmed in the extended cohort (P=.004; 97 vs. 56 transmissions). The subphenotypes of Crohn disease, ulcerative colitis, and mixed IBD contributed equally to this linkage, suggesting a general role for the chromosome 6 locus in IBD. Analysis of five single-nucleotide polymorphisms in the TNFA and LTA genes did not reveal evidence for association of these important candidate genes with IBD. In summary, we provide firm linkage evidence for an IBD-susceptibility locus on chromosome 6p and demonstrate that TNFA and LTA are unlikely to be susceptibility loci for IBD.

CANCER SURVEILLANCE IN ULCERATIVE COLITIS: Experience over 15 years

In the years 1966-80, 303 patients with radiologically extensive ulcerative colitis were followed up regularly, both by clinical assessment and by mucosal biopsies, to detect dysplastic (precancerous) change. Moderate or severe dysplasia (but no carcinoma) was found in the specimen in 8 patients treated surgically. Despite regular surveillance, carcinoma developed in 13 of the 186 patients with a history of disease for ten years or more. Of the total sixteen carcinomas in these 13 patients, eleven were Dukes stage A, three stage B, one stage C, and one was inoperable. There has been 1 death from carcinoma in this series over the fifteen year observation period. The method of follow-up has probably prevented the development of carcinoma in 8 patients and permitted diagnosis of carcinoma at a stage when cure is likely in 11. The incidence of moderate or severe dysplasia and carcinoma in these patients with mild or symptomless extensive colitis shows that either proctocolectomy or careful follow-up should be advised once the duration of symptoms reaches ten years.

Genetic Analysis of Inflammatory Bowel Disease in a Large European Cohort Supports Linkage to Chromosomes 12 and 16

BACKGROUND & AIMS Inflammatory bowel disease (IBD) is a complex disorder of unknown etiology. Epidemiological investigations suggest a genetic basis for IBD. Recent genetic studies have identified several IBD linkages. The significance of these linkages will be determined by studies in large patient collections. The aim of this study was to replicate IBD linkages on chromosomes 12 and 16 in a large European cohort. METHODS Three hundred fifty-nine affected sibling pairs from 274 kindreds were genotyped using microsatellite markers spanning chromosomes 12 and 16. Affection status of the sibling pairs was defined as Crohns disease (CD) or ulcerative colitis (UC). RESULTS Nonparametric statistical analyses showed linkage for both chromosomes. Two-point results for chromosome 12 peaked at D12S303 (logarithm of odds [LOD], 2.15; P = 0.003) for CD and at D12S75 (LOD, 0.92; P = 0.03) for UC. Multipoint analyses produced a peak LOD of 1.8 for CD. Chromosome 16 showed linkage for CD at marker D16S415 (LOD, 1.52; P = 0.007). Multipoint support peaked above markers D16S409 and D16S411 (LOD, 1.7). CONCLUSIONS These data are consistent with linkage of IBD to chromosomes 12 and 16. The replication of genetic risk loci in a large independent family collection indicates important and common susceptibility genes in these regions and will facilitate identification of genes involved in IBD.