Authors: Kalantar JS, Locke GR 3rd, Talley NJ, Zinsmeister AR, Fett SL, Melton LJ 3rd.

Institution: Department of Medicine, University of Sydney, Nepean Hospital, Penrith, NSW, Australia.

Background: We tested the hypothesis that subjects with relatives who suffered from abdominal pain or bowel dysfunction would be at an increased risk of more persistent irritable bowel syndrome.

Results: Subjects were less likely to have persistent irritable bowel syndrome over the age of 50 years [odds ratio (OR), 0.20; 95% confidence interval (CI), 0.09, 0.47]. A positive family history was reported by 23%. A family history of gastrointestinal symptoms was independently associated with persistent irritable bowel syndrome (vs. no irritable bowel syndrome: OR, 2.5; 95% CI, 1.3, 4.9) and fluctuating irritable bowel syndrome (vs. no irritable bowel syndrome: OR, 2.4; 95% CI, 1.3, 4.4). However, subjects reporting a positive family history were not more likely to report persistent vs. fluctuating irritable bowel syndrome (OR, 1.2; 95% CI, 0.5, 2.9). The use of non-steroidal anti-inflammatory drugs (OR, 2.3; 95% CI, 1.2, 4.3) and a history of food sensitivity (OR, 3.6; 95% CI, 1.9, 6.9) were the only other predictors of persistent irritable bowel syndrome.

Conclusions: A history of abdominal pain or bowel troubles in first-degree relatives appears to be independently associated with both persistent and fluctuating irritable bowel syndrome.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12786633&query_hl=4&itool=pubmed_docsum

Authors: Mohammed I, Cherkas LF, Riley SA, Spector TD, Trudgill NJ.

Institution: Department of Gastroenterology, Sandwell General Hospital, West Bromwich, United Kingdom.

Background: Aggregation of symptoms of abdominal pain or bowel disturbance has been described in the families of patients with irritable bowel syndrome (IBS). This may be due to environmental factors, including learned responses to abdominal symptoms or a genetic contribution to the etiology of IBS. OBJECTIVES: To determine the relative contribution of genetic factors to IBS by evaluating IBS symptoms in monozygotic (MZ) and dizygotic (DZ) twins.

Methods: A total of 4,480 unselected twin pairs identified from a national volunteer twin register were asked to complete a validated questionnaire. IBS was defined by the Rome II criteria.

Conclusion: Genetic factors are of little or no influence on IBS where the predominant influences appear to be environmental.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15929767&query_hl=64&itool=pubmed_docsum

Authors: Levy RL, Jones KR, Whitehead WE, Feld SI, Talley NJ, Corey LA.

Institution: University of Washington, Seattle, Washington 98195, USA. rlevy@u.washington.edu

Background: Heredity has been suggested to explain the finding that irritable bowel syndrome (IBS) tends to run in families. Research in this area has been limited. The aim of the present study was to assess the relative contribution of genetic and environmental (social learning) influences on the development of IBS by comparing concordance rates in monozygotic and dizygotic twins to concordance between mothers and their children.

Results: Analysis is based on 10,699 respondents representing 6060 twin pairs. Concordance for IBS was significantly greater (P = 0.030) in monozygotic (17.2%) than in dizygotic (8.4%) twins, supporting a genetic contribution to IBS. However, the proportion of dizygotic twins with IBS who have mothers with IBS (15.2%) was greater than the proportion of dizygotic twins with IBS who have co-twins with IBS (6.7%, P < 0.001), and logistic regression analysis showed that having a mother with IBS and having a father with IBS are independent predictors of irritable bowel status (P < 0.001); both are stronger predictors than having a twin with IBS. Addition of information about the other twin accounted for little additional predictive power.

Conclusions: Heredity contributes to development of IBS, but social learning (what an individual learns from those in his or her environment) has an equal or greater influence.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=11606493&query_hl=62&itool=pubmed_docsum

Authors: Howell S, Poulton R, Talley NJ.

Institution: Department of Medicine, University of Sydney, Nepean Hospital, Penrith, Australia.

Introduction: The natural history of childhood abdominal pain (CAP) and its association with adult irritable bowel syndrome (IBS) remain poorly described. We aim to investigate the characteristics of CAP over the first 11 yr of life and evaluate the association of CAP to IBS at age 26 yr.

Results: A history of CAP was reported by 18.1% of children. This was typically characterized by CAP on one assessment; complaints over two or more assessment were rare. CAP was slightly more common in females and appeared to peak at age 7-9 yr. IBS at age 26 yr was significantly more common among individuals with a history of CAP between ages 7 and 9 yr compared to those with no such history, as assessed by any history (OR = 1.85; p= 0.02), parental report (OR = 1.82; p= 0.03), and medical service encounters (OR = 3.75; p= 0.03). The association between CAP at age 7-9 yr and adult IBS was not altered by adjustment for sex, socio-economic status, psychiatric disorder at age 26 yr, childhood emotional distress, or mother's score on the Malaise Inventory.

Conclusions: CAP is a common complaint, which can progress to adult IBS in some children.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16128954&query_hl=46&itool=pubmed_docsum

Authors: Kanazawa M, Fukudo S.

No information currently available about this study.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16011677&query_hl=40&itool=pubmed_docsum