Crohn’s disease in adults: Observations in a multiracial Asian population

A Systematic Review on the Increasing Incidence of Inflammatory Bowel Disease in Southeast Asia: Looking Beyond the Urbanization Phenomenon

The incidence of inflammatory bowel disease (IBD) has been increasing in Southeast Asia (SEA) in tandem with its economic growth and urbanization over the past 2 decades. Specific characteristics of IBD in SEA are similar to East Asia and the West, such as the declining ratio of ulcerative colitis to Crohn's disease. However, exceptionally low familial aggregation is seen. Smoking is also not a common risk factor in patients with Crohn's disease. The incidence of perianal disease is higher in SEA than in Australia and is comparable to the West. In a multiracial population, such as Singapore and Malaysia, Indians have the highest incidence and prevalence rates, which are likely to be due to important putative mutations. For instance, a higher frequency of the NOD2 predisposing mutation SNP5 and IBD risk allele IGR2198a and IGR2092a were found in Indians. Although differences in the genetic constitution play an important role in the epidemiology and prognosis of IBD in SEA, the emergence of this disease offers a unique opportunity to identify potential exposomes that contribute to its pathogenesis.

A systematic review and meta-analysis of prevalence and clinical features of upper gastrointestinal (UGI) tract Crohn's disease in adults compared to non-UGI types

Background and Aim

Crohn's disease is an inflammatory condition that affects the gastrointestinal (GI) system. This study aimed to determine the prevalence of upper gastrointestinal Crohn's disease (UGICD) and compare its features to non-UGICD types.

Methods

We conducted a systematic search in the databases PubMed, Web of Science, Scopus, and Google Scholar. The heterogeneity of prevalence estimates was examined, subgroup analyses were carried out, and meta-analyses were conducted using random-effects modeling. Prognostic data were qualitatively reviewed and combined.

Results

Two-thousand nine-hundred and forty studies were retrieved and 32 studies were included in the final analysis. Pooled prevalence of UGICD was 15% (CI: 11-18%) among 14 509 patients. UGICD prevalence did not show any significant increase with time (P = 0.45). The most prevalent (38%, CI: 30-47%) behavior of UGICD was B1 (nonstricturing-nonpenetrating), while the most common concurrent location was L3 (ileocolon) with a prevalence of 47% (CI: 34-59%). UGICD patients had higher stricturing phenotype (B2) compared to non-UGICD (0.38 vs 0.30; P = 0.03). There was no significant difference in the prevalence of UGICD between patients classified according to the Montreal or Vienna classification. Stricturing phenotype was more common among Asian patients compared to Western patients (0.44 vs 0.24; P < 0.001). UGICD was a risk factor for surgery and drug therapy and was associated with an aggressive course of the disease and more resections. Pooled prevalence of UGICD was 15%.

Conclusion

Nonstricturing-nonpenetrating type was the most prevalent UGICD. UGICD patients had more complications and worse outcomes compared to non-UGICD patients.

Systematic review with meta-analysis: The prevalence, risk factors and outcomes of upper gastrointestinal tract Crohn's disease

AIMS

Upper gastrointestinal Crohn's disease (UGI-CD) is an important subclassification of Crohn's Disease (CD). We performed a systematic review and meta-analysis to evaluate the prevalence, risk factors, and clinical outcomes associated with UGI-CD.

METHODS

We searched Embase and Medline for articles reporting the clinical information of UGI-CD in CD patients, through 27 October 2020. Disease location and phenotype were coded according to the Montreal classification, and results were pooled with random effects by DerSimonian and Laird model.

RESULTS

26 articles were included. The prevalence of UGI-CD was 13%. UGI-CD was most commonly found in the stomach (56%) and was associated with concurrent ileocolonic involvement (54%). Non-stricturing, non-penetrating UGI-CD was the most common behavioral phenotype (61%). L4-jejunal disease was associated with the highest rates of surgery. Region of origin did not significantly influence the location and phenotype of UGI-CD. Young, male patients presenting with erythema nodosum, aphthous ulcers and stricturing-phenotype are more likely to have UGI-CD, which in turn is linked to increased risk of hospitalization and surgery.

CONCLUSION

UGI-CD is present in 13% of patients with CD, and patients with L4-jejunal disease are more likely to require surgery. Further studies examining the effect of ethnicity and region on UGI-CD are needed.

Genetic polymorphisms of ATG16L1 and IRGM genes in Malaysian patients with Crohn's disease

OBJECTIVE

To investigate the association between genetic polymorphisms in ATG16L1 and IRGM genes and the development of Crohn's disease (CD) in Malaysian patients.

METHODS

Altogether 335 participants were recruited, including 85 patients with CD and 250 unrelated healthy controls, and their informed consent was obtained. Genomic DNA was extracted via a conventional phenol-chloroform extraction method. Six single nucleotide polymorphisms (SNPs) in ATG16L1 and IRGM genes were genotyped using TaqMan SNP genotyping assays. Associations between SNP and CD were determined using Fisher's exact test, odds ratio, and 95% confidence interval. Statistical power and the Hardy-Weinberg equilibrium were also calculated.

RESULTS

Two SNPs (rs2241880 and rs6754677) in the ATG16L1 gene were significantly associated with the onset of CD in the Malaysian population. The A allele and homozygous A/A genotype of the rs2241880 A/G polymorphism were protective against CD in the overall Malaysian and Malay population. The G allele and homozygous G/G genotype of the rs6754677 G/A polymorphism were protective in the Indian population, whereas the homozygous A/A genotype showed a risk of developing CD. The homozygous G/G genotype of IRGM rs11747270 was significantly present in the controls. However, this significance was not observed in a race-stratified analysis. All three ATG16L1 SNPs were associated with inflamed terminal ileum. IRGM rs4958847 and rs11747270 increased the risk of developing arthritis in patients with CD.

CONCLUSION

We found a significant association between SNP, which are located in autophagy-related genes, and CD in a Malaysian population.

A four-decade analysis of the incidence trends, sociodemographic and clinical characteristics of inflammatory bowel disease patients at single tertiary centre, Kuala Lumpur, Malaysia

BACKGROUND

Inflammatory bowel disease (IBD) was once considered as a Western disease. However, recent epidemiological data showed an emerging trend of IBD cases in the Eastern Asia countries. Clinico-epidemiological data of IBD in Malaysia is scarce. This study aimed to address this issue.

METHODS

Retrospective analysis of ulcerative colitis (UC) and Crohn's disease (CD), diagnosed from January 1980 till June 2018 was conducted at our centre.

RESULTS

A total of 413 IBD patients (281 UC, 132 CD) were identified. Mean crude incidence of IBD has increased steadily over the first three decades: 0.36 (1980-1989), 0.48 (1990-1999) and 0.63 per 100,000 person-years (2000-2009). In the 2010 to 2018 period, the mean crude incidence has doubled to 1.46 per 100,000 person-years. There was a significant rise in the incidence of CD, as depicted by reducing UC:CD ratio: 5:1 (1980-1989), 5:1 (1990-1999), 1.9:1 (2000-2009) and 1.7:1 (2010-2018). The prevalence rate of IBD, UC and CD, respectively were 23.0, 15.67 and 7.36 per 100,000 persons. Of all IBD patients, 61.5% (n = 254) were males. When stratified according to ethnic group, the highest prevalence of IBD was among the Indians: 73.4 per 100,000 persons, followed by Malays: 24.8 per 100,000 persons and Chinese: 14.6 per 100,000 persons. The mean age of diagnosis was 41.2 years for UC and 27.4 years for CD. Majority were non-smokers (UC: 76.9%, CD: 70.5%). The diseases were classified as follows: UC; proctitis (9.2%), left-sided colitis (50.2%) and extensive colitis (40.6%), CD; isolated ileal (22.7%), colonic (28.8%), ileocolonic (47.7%) and upper gastrointestinal (0.8%). 12.9% of CD patients had concurrent perianal disease. Extra intestinal manifestations were observed more in CD (53.8%) as compared to UC (12%). Dysplasia and malignancy, on the other hand, occurred more in UC (4.3%, n = 12) than in CD (0.8%, n = 1). Over one quarter (27.3%) of CD patients and 3.6% of UC patients received biologic therapy.

CONCLUSION

The incidence of IBD is rising in Malaysia, especially in the last one decade. This might be associated with the urbanization and changing diets. Public and clinicians' awareness of this emerging disease in Malaysia is important for the timely detection and management.

Association of NOD1, CXCL16, STAT6 and TLR4 gene polymorphisms with Malaysian patients with Crohn's disease

Crohn's disease (CD) is a prominent type of inflammatory bowel disease (IBD) that can affect any part of the gastrointestinal tract. CD is known to have higher prevalence in the Western countries, but the number of cases has been increasing in the past decades in Asia, including Malaysia. Therefore, there is a need to investigate the underlining causes of CD that may shed light on its prevention and treatment. In this study, genetic polymorphisms in NOD1 (rs2075820), CXCL16 (rs2277680), STAT6 (rs324015) and TLR4 (rs4986791) genes were examined in a total of 335 individuals (85 CD patients and 250 healthy controls) with PCR-RFLP approach. There was no significant association observed between NOD1 rs2075820 and STAT6 rs324015 with the onset of CD in the studied cohort. However, the G allele of CXCL16 rs2277680 was found to have a weak association with CD patients (P = 0.0482; OR = 1.4310). The TLR4 rs4986791 was also significantly associated to CD. Both the homozygous C genotype (P = 0.0029; OR = 0.3611) and C allele (P = 0.0069; OR = 0.4369) were observed to confer protection against CD. On the other hand, the heterozygous C/T genotype was a risk genotype (P = 0.0015; OR = 3.1392). Further ethnic-stratified analysis showed that the significant associations in CXCL16 rs2277680 and TLR4 rs4986791 were accounted by the Malay cohort. In conclusion, the present study reported two CD-predisposing loci in the Malay CD patients. However, these loci were not associated to the onset of CD in Chinese and Indian patients.

Therapeutic efficacy of a mutant of keratinocyte growth factor-2 on trinitrobenzene sulfonic acid-induced rat model of Crohn's disease

BACKGROUND

Keratinocyte growth factor-2 (KGF-2) has been testified to be a multifunctional growth factor, which can stimulate the regeneration and reconstruction of epidermis, corium and mucosa. Its effect on Crohn's disease has hitherto not been evaluated. Here, we investigated the preventive and therapeutic actions of STEA, a mutant of human KGF-2 with high activity, on trinitrobenzene sulfonic acid (TNBS)-induced rat model of Crohn's disease.

METHODS

Rats with TNBS-induced colitis were treated with STEA and clinical scores were evaluated. Body weight, mortality, macroscopic and microscopic damage of the colonic tissue were examined. The levels of inflammatory cytokines in serum were detected by ELISA, the T cell subpopulations and the cell cycle of intestinal epithelial cells were analyzed by flow cytometry.

RESULTS

Both preventive and therapeutic administration of STEA significantly ameliorated body weight loss, diarrhea, and intestinal inflammation, reduced the high mortality and histopathologic damage of rats with TNBS-induced colitis. The serum level of inflammatory cytokines, such as TNF-α, IL-1β, IFN-γ and IL-6 were markedly decreased in colitis rats treated with STEA. The CD4+ and CD8+ T lymphocytes in peripheral blood were reduced with STEA administration at early stage of colitis. In addition, STEA treatment could promote the growth of intestinal epithelial cells by increasing the cell proportion in S phase of cell cycle and inhibiting cell apoptosis.

CONCLUSIONS

Both preventive and therapeutic administration of STEA could ameliorate the colonic damages in rats with TNBS-induced colitis. STEA might be a promising option for the treatment of Crohn's disease.

Asia Pacific Consensus Statements on Crohn's disease. Part 1: Definition, diagnosis, and epidemiology: (Asia Pacific Crohn's Disease Consensus--Part 1)

Inflammatory bowel disease (IBD) was previously thought to be rare in Asia, but emerging data indicate rising incidence and prevalence of IBD in the region. The Asia Pacific Working Group on Inflammatory Bowel Disease was established in Cebu, Philippines, at the Asia Pacific Digestive Week conference in 2006 under the auspices of the Asian Pacific Association of Gastroenterology with the goal of developing best management practices, coordinating research, and raising awareness of IBD in the region. The consensus group previously published recommendations for the diagnosis and management of ulcerative colitis with specific relevance to the Asia-Pacific region. The present consensus statements were developed following a similar process to address the epidemiology, diagnosis, and management of Crohn's disease. The goals of these statements are to pool the pertinent literature specifically highlighting relevant data and conditions in the Asia-Pacific region relating to the economy, health systems, background infectious diseases, differential diagnoses, and treatment availability. It does not intend to be all comprehensive and future revisions are likely to be required in this ever-changing field.

Risk of Major Abdominal Surgery in an Asian Population-based Crohn's Disease Cohort

BACKGROUND

Crohn's disease (CD) is increasing in incidence and prevalence in Asia, but there is a paucity of population-based studies on risk factors for surgery in Asian patients with CD. This will be useful to identify patients who may benefit from top-down treatment. This study describes the rates of abdominal surgery and identifies associated risk factors in Singaporean patients with CD.

METHODS

This was a retrospective observational study. The medical records of Singaporeans diagnosed with CD from 1970 to 2013 were reviewed from 8 different hospitals in Singapore. The cumulative probability of CD-related abdominal surgery was estimated using the Kaplan-Meier method. The logistic regression model was used to assess associations between independent risk factors and surgery.

RESULTS

The cohort of 430 Singaporean patients with CD included 63.5% Chinese, 11.9% Malay, and 24.7% Indians, with a male to female ratio of 1.6; median follow-up was 7.3 years (range, 2.9-13.0 yr) and median age at diagnosis 30.5 years (range, 19.5-43.7 yr). One hundred twelve patients (26.0%) required major abdominal surgery: the cumulative risk of surgery was 14.9% at 90 days, 21.2% at 5 years, 28.8% at 10 years, 38.3% at 20 years, and 50.6% at 30 years from diagnosis. Of the surgical patients, 75.0% were Chinese, 10.7% Malays, and 14.3% Indians; 21.4% underwent surgery for inflammatory disease, 40.2% for stricturing disease, and 38.4% for penetrating disease. Age at diagnosis (A2 17-40 yr, OR: 2.75, 95% confidence interval [CI], 1.14-7.76), ileal disease (L1 location, OR: 2.35, 95% CI, 1.14-5.0), stricturing (B2 OR: 6.09, 95% CI, 3.20-11.8), and penetrating behavior (B3 OR: 21.6, 95% CI, 9.0-58.8) were independent risk factors for CD-related abdominal surgery. Indian patients were less likely to require surgery (OR: 0.40, 95% CI, 0.19-0.78).

CONCLUSIONS

Age at diagnosis, L1 location, B2, and B3 disease behavior are independent risk factors for abdominal surgery. Interestingly, despite a higher prevalence of CD in Indians, a smaller proportion of Indian patients required surgery. These findings suggest that both environmental and genetic factors contribute to the risk of surgery in Asian patients with CD.

Exome sequencing identifies novel compound heterozygous IFNA4 and IFNA10 mutations as a cause of impaired function in Crohn's disease patients

Previous studies have highlighted the role of genetic predispositions in disease, and several genes had been identified as important in Crohn’s disease (CD). However, many of these genes are likely rare and not associated with susceptibility in Chinese CD patients. We found 294 shared identical variants in the CD patients of which 26 were validated by Sanger sequencing. Two heterozygous IFN variants (IFNA10 c.60 T > A; IFNA4 c.60 A > T) were identified as significantly associated with CD susceptibility. The single-nucleotide changes alter a cysteine situated before the signal peptide cleavage site to a stop code (TGA) in IFNA10 result in the serum levels of IFNA10 were significantly decreased in the CD patients compared to the controls. Furthermore, the IFNA10 and IFNA4 mutants resulted in an impairment of the suppression of HCV RNA replication in HuH7 cells, and the administration of the recombinant IFN subtypes restored DSS-induced colonic inflammation through the upregulation of CD4⁺ Treg cells. We identified heterozygous IFNA10 and IFNA4 variants as a cause of impaired function and CD susceptibility genes in Chinese patients from multiple center based study. These findings might provide clues in the understanding of the genetic heterogeneity of CD and lead to better screening and improved treatment.

A first study on the incidence and prevalence of IBD in Malaysia--results from the Kinta Valley IBD Epidemiology Study

BACKGROUND

Inflammatory bowel disease [IBD] is known to be rare in the Asia Pacific region but epidemiological studies are scarce.

METHODS

Kinta Valley [Ipoh] was chosen as the sample population. Malaysia has a multiethnic population consisting of Malays, Chinese, and Indians. New cases over 2 years were prospectively captured as well as all known existing cases. Total numbers of the population as a whole and of each ethnic group were obtained. Incidence, prevalence, and mean incidence over two decades were then calculated.

RESULTS

There were 10 new cases of IBD diagnosed from April 2011 to April 2013. The crude incidence rates of IBD, ulcerative colitis [UC], and Crohn's disease[CD], respectively, were 0.68, 0.46, and 0.20 per 100,000 persons. The highest incidence was among the Indians, 1.91 compared with 0.35 and 0.63 per 100,000 persons among the Malays and the Chinese, respectively. The mean incidence of IBD has increased steadily from 0.07 to 0.69 per 100,000 person-years over the past two decades. The UC:CD ratio was 8:1 from 1990 to 2000 and 3.6:1 from 2000 to 2010. The prevalence rates of IBD, UC, and CD, respectively, were 9.24, 6.67, and 2.17 per 100,000 persons. The highest prevalence also was among the Indians: 24.91 compared with 7.00 and 6.90 per 100,000 persons among the Malay and Chinese races, respectively.

CONCLUSIONS

The incidence and prevalence rates of IBD are low in Malaysia but the incidence appears to be increasing and marked racial differences exist. As in other Asian countries, the incidence of CD is increasing at a more rapid rate relative to UC.

Association between genetic polymorphisms in interferon regulatory factor 5 (IRF5) gene and Malaysian patients with Crohn's disease

OBJECTIVE

The study aimed to investigate the association between the interferon regulatory factor 5 (IRF5) gene polymorphisms and the onset of Crohn's disease (CD) in a Malaysian cohort.

METHODS

Genomic DNA was extracted from blood samples collected from 91 CD patients and 100 healthy individuals via a conventional phenol-chloroform extraction method. Screening of the four target single nucleotide polymorphisms (SNPs), including rs3807306, rs4728142, rs10954213 and rs11770589 was carried out in a real-time polymerase chain reaction (PCR) thermal cycler using TaqMan genotyping assay. The genetic data obtained was subsequently subjected to statistical analysis to relate the SNPs to the onset of CD in the Malaysian population. The genotyping assay and data were further validated selectively by conventional PCR amplification of the SNP sites and DNA sequencing.

RESULTS

The rs3807306 G allele was a risk factor for CD (OR 2.3630, P = 0.00004), whereas the homozygous T genotype was protective against the disease (OR 0.2038, P = 0.00004). The heterozygous A/G genotype of rs10954213 was significantly associated with CD (OR 4.319, P = 0.0377). On the other hand, the homozygous A and heterozygous A/G genotypes of the rs11770589 were significant in the controls (OR 0.4242, P = 0.0166) and patients (OR 2.000, P = 0.0179), respectively. In the ethnic-stratification analysis, the rs11770589 homozygous A genotype was protective in Indians (OR 0.1551, P = 0.0112).

CONCLUSION

IRF5 gene polymorphisms may play a role in the development of CD in the Malaysian population.

Increased fracture risk and osteoporosis not associated with vitamin D levels in Malaysian patients with inflammatory bowel disease

INTRODUCTION

Osteoporosis and osteopenia are well-recognized complications of inflammatory bowel disease. Previous studies have suggested that vitamin D deficiency is an important risk factor for the development of osteoporosis. We hypothesized that low vitamin D levels is the main reason for reduced bone mineral density in patients with inflammatory bowel disease. We aimed to study its potential role in Malaysia, which is a tropical country with 3 large ethnic groups. We also sought to examine the relationship between fracture risk and bone mineral density in this group.

METHODOLOGY

Relevant history as well as 25-hydroxycholecalciferol (vitamin D) levels and bone mineral density were obtained. Normal, inadequate, and low vitamin D levels were defined as 61-160 nmol/L (24-64 ng/mL), 30-60 nmol/L (12-24 ng/mL), and less than 30 nmol/L (<12 ng/mL), respectively.

RESULTS

Seventy-two patients were recruited. The prevalence of osteopenia and osteoporosis, respectively, were 58% and 17% in the spine and 51% and 14% in the hip. Mean vitamin D level in the group was low at 45.12 ± 17.4 nmol/L (18.05 ± 6.96 ng/mL), but there was no significant association between bone mineral density and vitamin D level. Twelve patients (16.7%) had a fragility fracture after the diagnosis of inflammatory bowel disease. The cumulative fracture incidence was 10% at 5 years and 35% at 10 years. There was a statistically significant association between osteoporosis of hip and a history of fracture (odds ratio 5.889; 95% confidence interval 1.41-24.53, P = .009).

CONCLUSION

Osteoporosis is prevalent among Malaysian patients with inflammatory bowel disease and is associated with a 6-fold increased risk of fractures. Most inflammatory bowel disease patients had inadequate or low vitamin D levels, but there was no association between vitamin D levels and BMD.

Hypothesis: Increased consumption of emulsifiers as an explanation for the rising incidence of Crohn's disease

Crohn's disease (CD) incidence has increased over the past fifty years but the explanation is unclear. CD can be brought into remission by liquid enteral feeding, but the mechanism for this response is unknown. We suggest that consumption of emulsifiers in processed foods may promote CD by increasing bacterial translocation. This is supported by evidence that (i) geographical variation in CD correlates with emulsifier consumption as does the increasing incidence of CD in Japan; (ii) although CD incidence also correlates with fat consumption, the response to enteral feeding is not affected by the fat content of the feed and (iii) very small concentrations of the emulsifier polysorbate 80 enhance bacterial translocation across intestinal epithelia. Undigested emulsifiers may increase bacterial translocation, particularly in the small intestine where the mucus layer is discontinuous. The hypothesis should be testable by trials of enteral feeding with/without emulsifiers.

A genome-wide association study identifies 2 susceptibility Loci for Crohn's disease in a Japanese population

BACKGROUND & AIMS

Crohn's disease is an inflammatory bowel disease induced by multiple genetic and environmental factors. Genome-wide association studies have identified genetic factors that affect the risk for Crohn's disease in European populations, but information from other ethnic groups is scarce. We therefore investigated genetic factors associated with Crohn's disease in the Japanese population.

METHODS

We performed a genome-wide association study with 372 individuals with Crohn's disease (cases) and 3389 controls, all from the Japanese population. To confirm identified associations, we performed a replication study with an independent panel of 1151 Crohn's disease cases and 15,800 controls. We also performed an association analysis using genome-wide genotype imputation in the discovery cohort.

RESULTS

We confirmed associations of Crohn's disease with variants in MHC (rs7765379, P = 2.11 × 10(-59)), TNFSF15 (rs6478106, P = 3.87 × 10(-45)), and STAT3 (rs9891119, P = 2.24 × 10(-14)). We identified 2 new susceptibility loci: on chromosome 4p14 (rs1487630, P = 2.40 × 10(-11); odds ratio, 1.33), and in the SLC25A15-ELF1-WBP4 region on 13q14 (rs7329174 in ELF1, P = 5.12 × 10(-9); odds ratio, 1.27).

CONCLUSIONS

In a genome-wide association study, we identified 2 new susceptibility loci for Crohn's disease in a Japanese population. These findings could increase our understanding of the pathogenesis of Crohn's disease.

Association between inflammatory bowel disease gene 5 (IBD5) and interleukin-23 receptor (IL23R) genetic polymorphisms in Malaysian patients with Crohn's disease

OBJECTIVE

This study was aimed to investigate the possible association of Crohn's disease (CD) with inflammatory bowel disease gene 5 (IBD5) IGR2198a_1 (rs11739135), IGR2096a_1 (rs12521868) and interleukin-23 receptor (IL23R) genetic variant (rs1004819) in the Malaysian population.

METHODS

Blood samples from 80 CD patients and 100 healthy controls were recruited. Genomic DNA was extracted and analyzed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

The results revealed that there was an increased frequency of IGR2198a_1 C allele (8.8% in CD, 1.5% in controls, P < 0.05, OR 6.30, 95% CI 1.77-22.31) and IGR2096a_1 T allele (6.9% in CD, 1.5% in controls, P < 0.05, OR 4.85, 95% CI 1.33-17.69) in the CD patients as compared to the controls, suggesting the two variants were potential risk factors of CD. Both risk alleles (C and T) were highest in Indians. In contrast, no significant difference was observed for the IL23R gene variant (rs1004819) between these two groups (P = 0.941). All genotypes and alleles of this gene variant were present in equal ratios in the CD and control groups (OR 1.02, 95% CI 0.66-1.57 for T allele and OR 0.98, 95% CI 0.64-1.52 for C allele).

CONCLUSIONS

There is a strong association between both IBD5 locus variants but not the IL23R gene variant with CD in the Malaysian population. The IBD5 locus variants were highest in Indians, which may explain the increased susceptibility of this particular ethnic group to the disease.

Inflammatory bowel disease in Asia: a systematic review

The incidence and prevalence of inflammatory bowel diseases (IBD), Crohn's disease (CD) and ulcerative colitis (UC), are lower in Asia than in the West. However, across Asia the incidence and prevalence of IBD has increased rapidly over the last two to four decades. These changes may relate to increased contact with the West, westernization of diet, increasing antibiotics use, improved hygiene, vaccinations, or changes in the gut microbiota. Genetic factors also differ between Asians and the Caucasians. In Asia, UC is more prevalent than CD, although CD incidence is rapidly increasing in certain areas. There is a male predominance of CD in Asia, but a trend towards equal sex distribution for UC. IBD is diagnosed at a slightly older age than in the West, and there is rarely a second incidence peak as in the West. A positive family history is much less common than in the West, as are extra-intestinal disease manifestations. There are clear ethnic differences in incidence within countries in Asia, and an increased incidence in IBD in migrants from Asia to the West. Research in Asia, an area of rapidly changing IBD epidemiology, may lead to the discovery of critical etiologic factors that lead to the development of IBD.

Identification of DLG5 and SLC22A5 gene polymorphisms in Malaysian patients with Crohn's disease

OBJECTIVE

The aim of this study was to investigate the association of DLG5 and SLC22A5 gene polymorphisms with the onset of Crohn's disease (CD) in a Malaysian cohort.

METHODS

Genomic DNA of 80 CD patients and 100 healthy unrelated control individuals was extracted and analyzed via polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) on DLG5 (4136 C/A), DLG5_e26 and SLC22A5 (-207 G/C) genetic polymorphisms. Data obtained from the study were then subjected to statistical analysis to test for risk association.

RESULTS

Significant associations of both DLG5 polymorphisms with the development of CD in the Malaysian patients were observed in this study. The homozygous C genotype of the DLG5 polymorphism was significantly related to CD patients (P = 0.0023, OR = 2.5320), while the homozygous A was significant in control individuals (P = 0.0224, OR = 0.4480). In DLG5_e26 polymorphisms, we found a significant distribution of the homozygous insA genotype in CD patients (P = 0.0006, OR = 2.8916), whereas the heterozygous insA/delA genotype was significant in controls (P = 0.0007, OR = 0.3487). We hypothesized that there might be a complex interaction of both alleles, which confered a protective effect against the onset of CD. However, we did not observe any significant correlation of SLC22A5 polymorphisms with this disease.

CONCLUSIONS

In our study, both polymorphisms in the DLG5 gene were found to be associated with CD patients in Malaysia. Therefore, these loci can be potentially used as susceptibility markers in the Malaysian population.

Population-specific susceptibility to Crohn's disease and ulcerative colitis; dominant and recessive relative risks in the Japanese population

Crohn's disease (CD), a type of chronic inflammatory bowel disease (IBD), is commonly found in European and East Asian countries. The calculated heritability of CD appears to be higher than that of ulcerative colitis (UC), another type of IBD. Recent genome-wide association studies (GWAS) have identified more than thirty CD-associated genes/regions in the European population. In the East Asian population, however, a clear association between CD and an associated gene has only been detected with TNFSF15. In order to determine if CD susceptibility differs geographically, nine SNPs from seven of the European CD-associated genomic regions were selected for analysis. The genotype frequencies for these SNPs were compared among the 380 collected Japanese samples, which consisted of 212 IBD cases and 168 controls. We detected a significant association of both CD and UC with only the TNFSF15 gene. Analysis by the modified genotype relative risk test (mGRR) indicated that the risk allele of TNFSF15 is dominant for CD, but is recessive for UC. These results suggest that CD and UC susceptibility differs between the Japanese and European populations. Furthermore, it is also likely that CD and UC share a causative factor which exhibits a different dominant/recessive relative risk in the Japanese population.

Recent insights in the epidemiology of autoimmune diseases: improved prevalence estimates and understanding of clustering of diseases

Previous studies have estimated a prevalence of a broad grouping of autoimmune diseases of 3.2%, based on literature review of studies published between 1965 and 1995, and 5.3%, based on national hospitalization registry data in Denmark. We examine more recent studies pertaining to the prevalence of 29 autoimmune diseases, and use these data to correct for the underascertainment of some diseases in the hospitalization registry data. This analysis results in an estimated prevalence of 7.6-9.4%, depending on the size of the correction factor used. The rates for most diseases for which data are available from many geographic regions span overlapping ranges. We also review studies of the co-occurrence of diseases within individuals and within families, focusing on specific pairs of diseases to better distinguish patterns that may result in insights pertaining to shared etiological pathways. Overall, data support a tendency for autoimmune diseases to co-occur at greater than expected rates within proband patients and their families, but this does not appear to be a uniform phenomenon across all diseases. Multiple sclerosis and rheumatoid arthritis is one disease pair that appears to have a decreased chance of coexistence.

Crohn's disease in India: a multicenter study from a country where tuberculosis is endemic

Although Crohn's disease is thought to be rare and intestinal tuberculosis common in India, Crohn's disease is being reported more often. However, there is a lack of systematic study on Crohn's disease from India. In this analysis of data from three inflammatory bowel disease clinics (two in northern India and one in eastern India), criteria for Crohn's disease were applied retrospectively: (1) World Health Organization (WHO) criteria; or (2) compatible histology (European Crohn's and Colitis Organization) or failure of response to 4-8 weeks of anti-tuberculosis therapy (Asia-Pacific guidelines); or (3) compatible macroscopic, radiologic, colonoscopic features (European Crohn's and Colitis Organization). Others were classified as probable Crohn's disease. The Montreal classification was used for disease phenotype. Age at onset and duration of symptoms (182 patients, 117 male) were 34.5 (+/-13.6; 7-73) years and 3.0 (+/-5.8; 0.1-36) years, respectively. Diarrhea (68%), abdominal pain (62%), and weight loss (57%) were common. The common intestinal complications were occult (27%) and overt (40%) gastrointestinal bleeding and obstruction (28%). There were 141 (78%) and 41 (22%) with definite and probable Crohn's disease respectively. Of 147 (81%) available histopathology specimens (endoscopic biopsy in 110; 75%), 31 (21%) had granuloma. Seventy-one out of 166 (43%) had received anti-tuberculosis therapy in the past. Results from the Montreal classification were as follows: age at onset, A1:A2:A3 6%:64%:30%; location of disease, L1:L2:L3:L4 32%:41%:23%:4%, and disease behavior, B1:B2:B3 51%:24%:25%. Twenty-six (15%) and 31 (17%) patients had upper gastrointestinal and perianal modifiers. The drugs used were: aminosalicylates (128, 70%), steroids (76, 42%), azathioprine (53, 29%), methotrexate (4, 2%), and salazopyrine (14, 8%). Sixty-six (36%) patients underwent surgical treatment. We concluded that the phenotype of Crohn's disease in India is very similar to that described in other regions of Asia and the West, except for a delay in diagnosis and a more complicated disease at diagnosis.

Identification of NOD2/CARD15 mutations in Malaysian patients with Crohn's disease

OBJECTIVE

The NOD2/CARD15 gene has been identified as an important susceptibility gene for Crohn's disease (CD) but the three common disease predisposing mutations (DPM) found in developed countries have not been identified in Asian populations. The aim of our study was to look for the DPM in our multiracial population and to discover whether there were any differences in the three major ethnic groups; Malay, Chinese and Indian.

METHODS

Blood samples from consecutive CD patients and healthy controls were obtained and analyzed for the three common mutations (R702W, G908R, 1007fs) but in addition to this, we also looked for the SNP5 and JW1 variants which are associated with CD in Ashkenazi Jews. A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used to identify the mutations, which was confirmed by sequencing. The baseline socio-demography and clinical characteristics of the CD patients were recorded.

RESULTS

Overall 45 patients (three Malays, 15 Chinese, 26 Indians and one other) with confirmed CD and 300 controls were recruited. The three common DPM were not observed in either the CD patients or the controls. Neither the SNP5 nor the JW1 mutation was found in any of the controls. However, the SNP5 mutation was identified in six (13.3%) Indian CD patients and the JW1 mutation in eight CD patients who are different from those carrying the SNP5 mutation: one Malay (33.3%), two Chinese (13.3%), one other (Portuguese) and four Indians (15.4%). The presence of SNP5 was strongly associated with CD in the Indian population and that of JW1 was strongly associated with CD overall and in each of the major ethnic groups. There was a trend towards a younger age of onset and stricturing disease in patients carrying the JW1 mutation.

CONCLUSION

These findings suggest the presence of novel DPM in the NOD2/CARD15 gene in Asian patients with CD.

Inflammatory bowel disease: a survey of the epidemiology in Asia

Inflammatory bowel disease (IBD) has long been considered a disease that affects predominantly a Western population. The incidence and prevalence rates from Asian populations are much lower in comparison. More recent data, however, have shown significantly higher rates in Asians and time trend studies have shown an increase in the incidence of ulcerative colitis (UC) and a similar but lower rise in Crohn's disease (CD). The epidemiological changes that are taking place mirror that of the Western experience seen 50 years previously and seem to occur in parallel with the rapid socioeconomic development taking place in Asia. It appears that certain racial groups are more prone than others to develop IBD. For instance, Indians in South-East Asia have higher rates compared to Chinese and Malays. While there is host genetic predisposition, environmental factor(s) may be responsible for this difference. Migrant studies of South Asians in the UK, where second-generation immigrants have assumed incidence rates as high as the indigenous whites and Asian Jews who develop high incidence rates comparable to Jews from Europe or North America in Israel point to the role of environmental factors. It is unclear which specific factors are responsible. Studies have suggested a change in diet to a more Westernized one may underlie this epidemiological change in the Asian population. It is likely that there are racial groups amongst Asians who are more susceptible to IBD and who will demonstrate a higher frequency of IBD when exposed to putative environmental factors.

Demography and clinical course of ulcerative colitis in a multiracial Asian population: a nationwide study from Malaysia

OBJECTIVE

To establish the clinical course of ulcerative colitis (UC) in the Malaysian population, comparing the three major ethnic groups: Malay, Chinese and Indian.

METHODS

Patients who were diagnosed with UC from seven major medical referral centers in Malaysia were recruited. Their baseline characteristics, and the extent of the disease, its clinical course and complications were recorded.

RESULTS

A total of 118 patients was included. The extent of disease was as follows: proctitis alone in 22 (18.6%), sigmoid colon in 23 (19.5%), descending colon in 16 (13.6%), transverse colon in 11 (9.3%), ascending colon and pancolitis 46 (39%). Most patients had chronic intermittent disease. Extra-intestinal complications were seen in 27 (22.9%) patients and fulminant colitis was seen in four (3.4%). None developed colorectal cancer. The overall cumulative colectomy rates at 1, 5 and 10 years were 3.4% (CI: 0.9-8.5), 5.9% (CI: 1.9-13.2) and 15.6% (CI: 6.5-29.4), respectively. There was a higher prevalence of extra-intestinal manifestations and a trend towards more extensive disease among Indian patients. However, no significant differences were seen in the age of onset, the severity of disease (fulminant colitis, refractory disease) and the colectomy rate.

CONCLUSION

As in developed countries, most of our patients have a remitting and relapsing pattern of disease but the clinical course appears to be milder, with lower rates of colectomies. There are differences in clinical presentation among the three major ethnic groups, with Indians having a higher prevalence of extra-intestinal manifestations and a trend towards more extensive disease.

An update on the epidemiology of inflammatory bowel disease in Asia

A rising trend in the incidence and prevalence of inflammatory bowel disease (IBD) in Asia has been recognized for the past two decades. It has been postulated that this phenomenon may be related to the westernization of lifestyles, including changes in dietary habits and environmental changes such as improved sanitation and industrialization. Previously we reported that the incidence and prevalence rates of IBD in Asia were low compared with the West, but there was a notably rising secular trend. In this review, we summarize the recent epidemiological data in Asia, characterize the clinical features, risk factors and genetic susceptibility of Asian IBD patients, and compare these to those of Western IBD patients. In the past decade, the incidence and prevalence of IBD reported across Asia, particularly in East Asia, has continued to increase. Familial clustering is generally uncommon in East Asia but appears to be higher in West Asia. The genetic susceptibilities in Asian IBD patients differ from those of White patients, as NOD2/CARD15 mutations are much less common. The clinical phenotypes and complication rates of Asian IBD resemble the White population in general, but with some differences, including lower surgical rates, higher prevalence of males, and higher prevalence of ileocolonic involvement among East Asian Crohn's disease patients, and a low frequency of primary sclerosing cholangitis among IBD patients in East and Southeast Asia.

Classification of genetic profiles of Crohn's disease: a focus on the ATG16L1 gene

Inflammatory bowel disease constitutes two related clinical entities, Crohn's disease (CD) and ulcerative colitis (UC), both of which have increased in prevalence over the last decade. Family and twin studies have strongly indicated that genetic factors play a large role in an individual's risk of developing inflammatory bowel disease. Despite this, it has proven difficult to isolate disease genes that confer susceptibility to this disease using classical candidate gene and linkage approaches, with the notable exception of the isolation of the caspase recruitment domain family, member 15 (CARD15) gene. However, over the last 2 years, genome-wide association (GWA) studies have become feasible, where modern high-throughput single nucleotide polymorphism (SNP) genotyping technologies can be applied to large and comprehensively phenotyped patient cohorts. Such approaches have enabled scientists to robustly associate specific variants with many complex diseases, including age-related macular degeneration, Type 2 diabetes, breast cancer and asthma. In the inflammatory bowel disease field, positive associations with CD and UC coming from GWA studies have been reported for an ever increasing number of genes. The most consistently and strongly associated variants have been in the CARD15, the interleukin 23 receptor (IL23R) and autophagy-related 16-like 1 (ATG16L1) genes. With respect to ATG16L1, the G allele of SNP rs2241880 has been shown in multiple association studies to confer strong risk for CD, although its association with UC remains more debatable. This SNP is in fact a common coding variant, specifically a threonine-to-alanine substitution at amino acid position 300 of the ATG16L1 protein (T300A), and appears to account for all of the disease risk conferred by this locus. This review addresses recent advances in GWA studies of inflammatory bowel disease, with specific focus on the growing evidence of the ATG16L1 gene's role in CD and how its protein product operating within the autophagic pathway makes autophagy an attractive therapeutic target for this debilitating disorder.

New global map of Crohn's disease: Genetic, environmental, and socioeconomic correlations

Seventy-five years after the initial characterization of Crohn's disease (CD), much remains obscure about its etiology. The authors sought to evaluate the incidence trends of the last 25 years worldwide, and the existence of potential correlations with genetic, environmental, and socioeconomic factors that could be etiologically implicated in the pathogenesis of CD. Relevant medical literature for individual countries on the incidence of CD, on the incidence of associated genetic mutations, and on the incidence of suggested etiologic infectious agents such as Mycobacterium avium paratuberculosis were retrieved from published medical literature, reports from relevant international congresses, and through official reports from national health authorities. Increasing trends have been observed almost worldwide, with a broad north-south gradient still prevailing in Europe. Distinct regions of New Zealand, Canada, Scotland, France, the Netherlands, and Scandinavia represent the highest incidence areas. Industrialized status and affluence are the common denominators between endemic areas, but are too broad as terms to strongly indicate any particular etiological role. The increasing trends observed in Asia still account for a low prevalence of the disease and may represent increased detection and diagnostic ability of local health systems. Genetic associations are variably reproduced worldwide, in a manner inconsistent with a strong etiologic relationship. Data on paratuberculosis incidence are scarce, and the existing ones are ambivalent regarding an even indirect correlation between CD and an infectious trigger.

Crohn’s disease in one mixed-race population in Brazil

AIM: To evaluate the classification and severity of Crohn's disease in different racial groups.

METHODS: Patients with Crohn’s disease from the outpatient clinic of the University Hospital Prof. Edgard Santos were enrolled in the study. This hospital is a reference centre for inflammatory bowel disease. Race was determined using self-identification. The Vienna's classification was applied for all subjects. The severity of Crohn's disease was determined according to the number of surgical procedures, hospital admissions in the last year and treatment with steroids and immunosuppressors. Statistical analysis was calculated using t test for means, χ² or F for proportions. A P value < 0.05 was considered to be significant.

RESULTS: Sixty-five patients were enrolled. Non-white patients were more frequently diagnosed with Crohn’s disease in the age less than 40 years than white patients. The behaviour of disease was similar in both groups with a high frequency of the penetrating form. There was a tendency for non-white patients to have a greater frequency of hospital admissions in the last year compared to white subjects. Non-whites also had a higher rate of colonic and upper gastrointestinal involvement, and were also more frequently on treatment with immunossupressors than white patients although this difference was not statistically significant.

CONCLUSION: Non-white patients with Crohn’s disease had an earlier diagnosis and appeared to have had a more severe disease presentation than white patients.

Association analysis of genetic variants in IL23R, ATG16L1 and 5p13.1 loci with Crohn's disease in Japanese patients

Inflammatory bowel diseases, Crohn's disease (CD) and ulcerative colitis are characterised by chronic transmural, segmental and typically granulomatous inflammation of the gut. Each has a peak age of onset in the second to fourth decades of life and prevalence has been increasing significantly in both Western countries and Japan over the last decade, while their pathogenesis remains largely unknown. Recently, positive association of CD with the variants in interleukin 23 receptor (IL23R), autophagy-related 16-like 1 (ATG16L1) genes and chromosome 5p13.1 locus was reported through genome-wide association studies which are now recognised as a robust tool for the identification of susceptibility genes for complex diseases. To examine an association of reported susceptible variants in the three loci with Japanese CD patients, a total of 484 CD patients and 439 controls were genotyped. No evidence of positive association for any of these loci with CD was found in the Japanese population, even after clinically stratified subgroups of CD were used. Our result revealed a distinct ethnic difference of genetic background of CD that we reported previously in other genes between Japanese and Caucasian populations. Further genetic studies are required to confirm our findings with ethnically divergent populations.