Due to study plan

The aim of this study is to compare the gut microbiota in Chinese patients with Inflammatory Bowel Disease (IBD) in Hong Kong with that of healthy controls, compare the gut microbiota in IBD patients in a developing country (low but increasing IBD incidence, Hong Kong) with those in a developed country (high incidence, Australia), compare the gut microbiota in Chinese patients with IBD in Hong Kong with the microbiota of their non-IBD affected parents and siblings.

Crohn's disease and ulcerative colitis are chronic inflammatory disorders of the gut that cause major life-long disability. Afflicting mostly young people at an age when they are most active both in their private and professional life, inflammatory bowel disease (IBD) represents an important public health problem affecting both the patients education, working abilities, social life and quality of life. Previously a disease predominantly of the West, there is now a marked increase in the incidence of IBD in Hong Kong. The cause of this dramatic increase over the last decade is unknown. Genetic factors, environmental factors and the gut bacteria may play a role in disease development. This study aims to explore the factors that may be contributing to, or causing, the rise of IBD in Hong Kong. The investigators propose to study the gut bacteria in Chinese patients with IBD compared with non-IBD patients, and healthy relatives of IBD patients. IBD patients will be prospectively recruited, blood samples will be obtained for serology and genotyping, stool samples and biopsies will be collected during routine colonoscopy for microbiota analysis. Bloods, stool and tissue gut microbiota from non-IBD patients will be collected for comparison. Studying gut microbiota, genetics and environmental factors in populations with changing incidence of IBD offers the greatest hope of identifying potentially important causative factors for disease.

Inclusion Criteria:

• patients aged ≥18 with a diagnosis of Crohn's disease or ulcerative colitis defined by endoscopy, radiology and histology, patients on stable medication and informed consent obtained

Control group:

Healthy controls (non-IBD patients) will comprise ethnicity - matched patients undergoing colonoscopy for polyp or colorectal cancer screening, or rectal bleeding. Controls will be excluded if they have previously been diagnosed with IBD or if they have a first or second degree relative with IBD.

Relatives group:

Relatives of patients will be aged between 16 and 35 years. They will be a first degree relative of a patient. Relatives older than 35 will not be recruited to maximise the chance of including some individuals who will develop IBD in the future. Relatives will be contacted either via the patient or directly by telephone by the investigators. They will be invited to attend for a screening meeting to assess eligibility and to receive the information sheets. They will undergo a flexible sigmoidoscopy/colonoscopy for biopsies once fully consented.

Exclusion Criteria:

• Patient group:

  1. current infection with an enteric pathogen,
  2. use of antibiotics within the last month,
  3. consumption of any probiotic or prebiotic within the last month,
  4. imminent need for surgery,
  5. requiring hospitalization,
  6. pregnancy or lactation,
  7. short bowel syndrome
  8. previous proctocolectomy
  9. significant hepatic, renal, endocrine, respiratory, neurological or cardiovascular disease as determined by the principal investigator,
  10. if they have a history of cancer with a disease free state of less than two years

Control and Relative group:

1. previously been diagnosed with IBD
2. they have a first or second degree relative with IBD

Crohn's disease or ulcerative colitis patients as the case groups, Patients attend clinics or endoscopy for functional upper gastrointestinal diseases or screening colonoscopy as the control group, and the first degree relatives of IBD patients as the relative group