High incidence of inflammatory bowel disease in Northern Australia: a prospective community population-based Australian incidence study in the Mackay-Isaac-Whitsunday region

Higher incidence of paediatric inflammatory bowel disease by increasing latitude in Norway, but stable incidence by age

AIM

To examine possible geographical and temporal differences in the incidence of childhood-onset inflammatory bowel disease (IBD) in Norway, motivated by previous research indicating relevant environmental factors explaining changing epidemiology.

METHODS

We analysed data from children born in Norway from 2004 to 2012 (n = 541 036) in a registry-based nationwide study. After validating registry diagnoses against medical records, we defined IBD as ≥2 entries of International Classification of Diseases, 10th revision (ICD-10) codes K50, K51 and K52.3 in the Norwegian Patient registry. We estimated hazard ratios (HR) for IBD across four geographical regions with a south-to-north gradient and the incidence by period of birth.

RESULTS

By the end of follow-up on 31 December 2020, 799 IBD diagnoses were identified (Crohn's disease: n = 465; ulcerative colitis, n = 293, IBD: unclassified, n = 41). Compared to children in the southernmost region, there was almost a two-fold HR for IBD in children in the most Northern region (HR = 1.94, 95% Cl = 1.47-2.57; Mid region: HR = 1.68, 95% CI = 1.29-2.19, ptrend <0.001). These estimates remained largely unchanged after adjustment for potential confounding factors. The cohorts born in 2004-2006 and 2010-2012 had comparable cumulative incidences, with a slightly higher incidence for those born in 2007-2009.

CONCLUSION

We observed an increase in the risk of IBD by increasing latitude which may suggest that environmental factors influence the development of IBD, although non-causal explanations cannot be ruled out.

The Epidemiology of Inflammatory Bowel Disease in Oceania: A Systematic Review and Meta-Analysis of Incidence and Prevalence

BACKGROUND

Past studies have shown high rates of inflammatory bowel disease (IBD) in Australia and New Zealand (NZ). We aimed to describe the epidemiology of IBD in Australia, NZ, and the surrounding region (collectively termed Oceania) by conducting a systematic review and meta-analysis.

METHODS

Electronic databases were searched from inception to April 2023 for studies reporting incidence or prevalence rates of IBD, Crohn's disease (CD), or ulcerative colitis (UC) in Oceania. All study designs were included. A meta-analysis calculated pooled estimates of incidence and prevalence, and a sensitivity analysis compared the pooled population-based studies with the non-population-based studies and the Australian and NZ studies separately.

RESULTS

Nineteen incidence and 11 prevalence studies were included; 2 studies were from the Pacific Islands, with the rest coming from Australia and NZ. Pooled estimates showed high incidence rates of 19.8 (95% confidence interval [CI], 15.8-23.7) for IBD, 8.3 (95% CI, 6.9-9.8) for CD, and 7.4 (95% CI, 5.7-9.1) for CD per 100 000 person-years. CD was more common than UC in most studies. The pooled estimates for the prevalence studies were 303.3 (95% CI, 128.1-478.4) for IBD, 149.8 (95% CI, 71.0-228.5) for CD, and 142.2 (95% CI, 63.1-221.4) for UC per 100 000 persons. Studies using population-based data collection methods showed higher pooled rates for both incidence and prevalence.

CONCLUSIONS

The incidence and prevalence of IBD in Oceania is high. The studies were heterogeneous and there were several geographic areas with no information, highlighting the need for more epidemiological studies of IBD.

Crosstalk between alternative splicing and inflammatory bowel disease: Basic mechanisms, biotechnological progresses and future perspectives

BACKGROUND

Alternative splicing (AS) is an omnipresent regulatory mechanism of gene expression that enables the generation of diverse splice isoforms from a single gene. Recently, AS events have gained considerable momentum in the pathogenesis of inflammatory bowel disease (IBD).

METHODS

Our review has summarized the complex process of RNA splicing, and firstly highlighted the potential involved molecules that target aberrant splicing events in IBD. The quantitative transcriptome analyses such as microarrays, next-generation sequencing (NGS) for AS events in IBD have been also discussed.

RESULTS

Available evidence suggests that some abnormal splicing RNAs can lead to multiple intestinal disorders during the onset of IBD as well as the progression to colitis-associated cancer (CAC), including gut microbiota perturbations, intestinal barrier dysfunctions, innate/adaptive immune dysregulations, pro-fibrosis activation and some other risk factors. Moreover, current data show that the advanced technologies, including microarrays and NGS, have been pioneeringly employed to screen the AS candidates and elucidate the potential regulatory mechanisms of IBD. Besides, other biotechnological progresses such as the applications of third-generation sequencing (TGS), single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics (ST), will be desired with great expectations.

CONCLUSIONS

To our knowledge, the current review is the first one to evaluate the potential regulatory mechanisms of AS events in IBD. The expanding list of aberrantly spliced genes in IBD along with the developed technologies provide us new clues to how IBD develops, and how these important AS events can be explored for future treatment.