Lisa A. Simms

Features of Colorectal Cancers with High-Level Microsatellite Instability Occurring in Familial and Sporadic Settings : Parallel Pathways of Tumorigenesis

High-level microsatellite instability (MSI-H) is demonstrated in 10 to 15% of sporadic colorectal cancers and in most cancers presenting in the inherited condition hereditary nonpolyposis colorectal cancer (HNPCC). Distinction between these categories of MSI-H cancer is of clinical importance and the aim of this study was to assess clinical, pathological, and molecular features that might be discriminatory. One hundred and twelve MSI-H colorectal cancers from families fulfilling the Bethesda criteria were compared with 57 sporadic MSI-H colorectal cancers. HNPCC cancers presented at a lower age (P < 0.001) with no sporadic MSI-H cancer being diagnosed before the age of 57 years. MSI was less extensive in HNPCC cancers with 72% microsatellite markers showing band shifts compared with 87% in sporadic tumors (P < 0.001). Absent immunostaining for hMSH2 was only found in HNPCC tumors. Methylation of hMLH1 was observed in 87% of sporadic cancers but also in 55% of HNPCC tumors that showed loss of expression of hMLH1 (P = 0.02). HNPCC cancers were more frequently characterized by aberrant beta-catenin immunostaining as evidenced by nuclear positivity (P < 0.001). Aberrant p53 immunostaining was infrequent in both groups. There were no differences with respect to 5q loss of heterozygosity or codon 12 K-ras mutation, which were infrequent in both groups. Sporadic MSI-H cancers were more frequently heterogeneous (P < 0.001), poorly differentiated (P = 0.02), mucinous (P = 0.02), and proximally located (P = 0.04) than HNPCC tumors. In sporadic MSI-H cancers, contiguous adenomas were likely to be serrated whereas traditional adenomas were dominant in HNPCC. Lymphocytic infiltration was more pronounced in HNPCC but the results did not reach statistical significance. Overall, HNPCC cancers were more like common colorectal cancer in terms of morphology and expression of beta-catenin whereas sporadic MSI-H cancers displayed features consistent with a different morphogenesis. No individual feature was discriminatory for all HNPCC cancers. However, a model based on four features was able to classify 94.5% of tumors as sporadic or HNPCC. The finding of multiple differences between sporadic and familial MSI-H colorectal cancer with respect to both genotype and phenotype is consistent with tumorigenesis through parallel evolutionary pathways and emphasizes the importance of studying the two groups separately.

Reduced alpha-defensin expression is associated with inflammation and not NOD2 mutation status in ileal Crohn’s disease

Background and aims: Reduced ileal Paneth cell α-defensin expression has been reported to be associated with Crohn’s disease, especially in patients carrying NOD2 mutations. The aim of this study was to independently assess whether NOD2, α-defensins and Crohn’s disease are linked. Methods: Using quantitative real-time polymerase chain reaction (RT-PCR), we measured the mRNA expression levels of key Paneth cell antimicrobial peptides (DEFA5, DEFA6, LYZ, PLA2G2A), inflammatory cytokines [interkelukin 6 (IL6) and IL8], and a marker of epithelial cell content, villin (VIL1) in 106 samples from both affected ileum (inflamed Crohn’s disease cases, n = 44) and unaffected ileum (non-inflamed; Crohn’s disease cases, n = 51 and controls, n = 11). Anti-human defensin 5 (HD-5) and haematoxylin/eosin immunohistochemical staining was performed on parallel sections from NOD2 wild-type and NOD2 mutant ileal Crohn’s disease tissue. Results: In Crohn’s disease patients, DEFA5 and DEFA6 mRNA expression levels were 1.9- and 2.2-fold lower, respectively, in histologically confirmed inflamed ileal mucosa after adjustment for confounders (DEFA5, p<0.001; DEFA6, p = 0.001). In contrast to previous studies, we found no significant association between α-defensin expression and NOD2 genotype. HD-5 protein data supports these RNA findings. The reduction in HD-5 protein expression appears due to surface epithelial cell loss and reduced Paneth cell numbers as a consequence of tissue damage. Conclusions: Reduction in α-defensin expression is independent of NOD2 status and is due to loss of surface epithelium as a consequence of inflammatory changes rather than being the inciting event prior to inflammation in ileal Crohn’s disease.

A family with attenuated familial adenomatous polyposis due to a mutation in the alternatively spliced region of APC exon 9

A family is presented with attenuated familial adenomatous polyposis of variable phenotype. The clinical features range from sparse right‐sided polyposis and cancer in the proximal colon at the age of 34 to pan‐colonic polyposis and cancer at the age of 68. Rectal sparing is common to all affected members. Heteroduplex analysis detected bands of altered mobility in exon 9 of the APC gene in all affected family members. Subsequently, a frameshift mutation was found in the alternatively spliced region of exon 9 at codon 398 which resulted in a stop signal 4 codons downstream. Alternatively spliced transcripts that delete the mutation were readily amplified from normal colonic mucosa and therefore create a mechanism for the attenuated phenotype seen in this family. Hum Mutat 11:450–455, 1998.

Sa1194 Consistently High C Reactive Protein Is Associated With Subsequent Development of Perianal Fistulae in Patients With Crohn's Disease

in the use of systemic steroids. Conclusions: At the moment of diagnosis of CD, smoking, abdominal pain, diarrhea, lower hemoglobin values and higher CPR, ESR or platelet values, as well as ileocolonic location of the disease, penetrating or stricturing disease, and perianal involvement are associated with a subsequent surgical outcome. The early recognition of these features in newly diagnosed patients should be seriously taken into account when deciding for more aggressive medical treatments, such as immunosuppressors or biological agents, in order to defer the more invasive surgical procedures.

Corrigendum: PACSIN2 Does Not Influence Thiopurine-Related Toxicity in Patients With Inflammatory Bowel Disease.

Corrigendum: PACSIN2 Does Not Influence Thiopurine-Related Toxicity in Patients With Inflammatory Bowel Disease

Su1335 A Novel Description of Longitudinal Phenotype in Patients With Crohn's Disease

BACKGROUND: The Montreal classification for patients with Crohns disease describes disease phenotype in a hierarchy: B1 (Inflammatory), B2 (Stricturing), B3 (Internal Penetrating). It does not make allowance for description of resolution, or of repeated development, of internal penetrating or stricturing complications (IPSC). It therefore always observes increasing severity of disease phenotype over time, and does not accurately represent the burden of IPSC later in the disease course. AIM: To describe a novel classification of longitudinal disease phenotype in Crohns disease, which allows description of both resolution and repeated development of IPSC. METHODS: Patients diagnosed at a tertiary referral centre (Brisbane, Australia) with Crohns disease between 1st Jan 1994 and 1st March 2008, with more than five years of clinical follow-up, had all objective clinical data recorded in a longitudinal database. Temporal evidence of presence of IPSC was obtained from the following: computed tomographic enterography (CTE), magnetic resonance enterography (MRE), ileocolonoscopy, gastroscopy, findings at abdominal surgery and examination of macroscopic surgical specimens. Disease phenotype at each time point was classified as the presence or absence of IPSC over the previous three years of disease course. Longitudinal disease phenotype was compared to progressive Montreal phenotype. Subgroup analysis was performed for patients with B1, B2 or B3 Montreal phenotype within one year of diagnosis. RESULTS: 316 patients with a median follow-up of 10.0 years (interquartile range (IQR) 6.81 13.67) were analyzed. Mean age at diagnosis was 27.4 years and 55% were female. Montreal location classification at diagnosis was L1 (131 patients), L2 (58) and L3 (117). Progressive Montreal phenotype was comparable to published cohorts.1 In comparison longitudinal phenotype classification demonstrated a predominance of stricturing complications. Stricturing complications predominated regardless of Montreal phenotype within the first year (graphs not shown). The steep slope in all lines at 3 years represents patients with an isolated IPSC at presentation regressing to a less severe classification. CONCLUSION: B2 (Stricturing) complications make up the bulk of recurring or non-resolving IPSC in patients with Crohns disease, regardless of Montreal phenotype within one year of diagnosis. This is not evident when disease classification is observed using the Montreal classification system alone. 1: Tarrant KM, Barclay ML, Frampton CMA, Gearry RB. Perianal disease predicts changes in Crohns disease phenotype-results of a population-based study of inflammatory bowel disease phenotype. Am J Gastroenterol. 2008 Dec;103(12):3082-93.

Su1336 The Pre-Diagnosis Inflammatory Signature of Patients With Inflammatory Bowel Disease

BACKGROUND: The Montreal classification for patients with Crohns disease describes disease phenotype in a hierarchy: B1 (Inflammatory), B2 (Stricturing), B3 (Internal Penetrating). It does not make allowance for description of resolution, or of repeated development, of internal penetrating or stricturing complications (IPSC). It therefore always observes increasing severity of disease phenotype over time, and does not accurately represent the burden of IPSC later in the disease course. AIM: To describe a novel classification of longitudinal disease phenotype in Crohns disease, which allows description of both resolution and repeated development of IPSC. METHODS: Patients diagnosed at a tertiary referral centre (Brisbane, Australia) with Crohns disease between 1st Jan 1994 and 1st March 2008, with more than five years of clinical follow-up, had all objective clinical data recorded in a longitudinal database. Temporal evidence of presence of IPSC was obtained from the following: computed tomographic enterography (CTE), magnetic resonance enterography (MRE), ileocolonoscopy, gastroscopy, findings at abdominal surgery and examination of macroscopic surgical specimens. Disease phenotype at each time point was classified as the presence or absence of IPSC over the previous three years of disease course. Longitudinal disease phenotype was compared to progressive Montreal phenotype. Subgroup analysis was performed for patients with B1, B2 or B3 Montreal phenotype within one year of diagnosis. RESULTS: 316 patients with a median follow-up of 10.0 years (interquartile range (IQR) 6.81 13.67) were analyzed. Mean age at diagnosis was 27.4 years and 55% were female. Montreal location classification at diagnosis was L1 (131 patients), L2 (58) and L3 (117). Progressive Montreal phenotype was comparable to published cohorts.1 In comparison longitudinal phenotype classification demonstrated a predominance of stricturing complications. Stricturing complications predominated regardless of Montreal phenotype within the first year (graphs not shown). The steep slope in all lines at 3 years represents patients with an isolated IPSC at presentation regressing to a less severe classification. CONCLUSION: B2 (Stricturing) complications make up the bulk of recurring or non-resolving IPSC in patients with Crohns disease, regardless of Montreal phenotype within one year of diagnosis. This is not evident when disease classification is observed using the Montreal classification system alone. 1: Tarrant KM, Barclay ML, Frampton CMA, Gearry RB. Perianal disease predicts changes in Crohns disease phenotype-results of a population-based study of inflammatory bowel disease phenotype. Am J Gastroenterol. 2008 Dec;103(12):3082-93.

35 Gene-Environment Interactions in Crohn's Disease: Identification of a Novel SNP That Interacts Strongly With Smoking to Shorten Time to First Resection

A Meta-Analysis of Genome Wide Association Scans Identifies TAGAP and Pus10 as Shared Risk Loci for Crohns Disease and Celiac Disease Eleonora A. Festen, Philippe Goyette, Todd Green, Claudine Beauchamp, Caroline Lagace, Gabrielle Boucher, Gosia Trynka, Patrick C. Dubois, Pieter Stokkers, Daniel W. Hommes, Donatella Barisani, Orazio Palmieri, Vito Annese, David van Heel, Rinse K. Weersma, Mark J. Daly, Cisca Wijmenga, John D. Rioux