Lack of Familial Aggregation in Chronic Constipation Excluding Irritable Bowel Syndrome: A Population-Based Study

Background: Despite strong evidence supporting a genetic and gene–environment interaction in the irritable bowel syndrome (IBS), the role of genes and early life in another common functional bowel disorder, chronic constipation (CC), have been little studied. Aim: To determine whether familial aggregation occurs in CC and whether risk factors differed in those with family members. Methods: A randomly selected population-based cohort from Olmsted County, MN, was surveyed (n = 8,006); 3,831 completed questionnaires (response rate 48 %). Cases were identified based upon their responses to a validated questionnaire and meeting Rome criteria for CC. Controls were matched one to one by age and gender. IBS (by Rome II criteria) was excluded. Recruitment of case and control probands occurred in 2010–2011 by mailing a family information form; then, first-degree relatives (FDR) were mailed a questionnaire. All potential proband participants were not informed of CC status. Results: Overall 1,185 cases who met criteria for CC without symptoms of IBS and 1,185 controls were surveyed; 309 case and 336 control probands provided data. The proportion of family members having CC was not associated with case status, and the constipation status of FDR was not significantly associated with case–controls status of the respective probands. Symptom burden in FDR was associated with gender and SSC score, but not age or proband status. Conclusions: No evidence of familial aggregation was observed in adults from the community with CC (excluding IBS). Our data suggest environmental factors in later life more likely account for adult CC.