Heritability and Familial Aggregation of Diverticular Disease: A Population-Based Study of Twins and Siblings

BACKGROUND & AIMS: Little is known about the role of heritable factors in diverticular disease. We evaluated the contribution of heritable factors to the development of diverticular disease diagnosed at a hospitalization or outpatient visit. METHODS: Using nationwide patient registries, we identified 142,123 incident cases of diverticular disease diagnosed at a hospitalization (1977-2011) or an outpatient hospital visit (1995-2011) in Denmark, including cases in 10,420 index siblings and 923 twins. We calculated standardized incidence ratios for siblings versus the general population and concordance rates for monozygotic versus dizygotic twin pairs as measures of relative risk (RR). RESULTS: The RR for diverticular disease in siblings of index cases was 2.92 (95% confidence interval [CI], 2.50-3.39) compared with the general population. The RRs were similar irrespective of the sex of the sibling or index case and were particularly strong in siblings of hospitalized cases and cases that underwent surgery. The proband-wise concordance rate for monozygotic twins was double that of dizygotic twins (0.16 [95% CI, 0.11-0.22] vs 0.07 [95% CI, 0.05-0.11], respectively). The RR of diverticular disease in one twin when the other had diverticular disease was 14.5 (95% CI, 8.9-23) for monozygotic twins compared with 5.5 (95% CI, 3.3-8.6) for dizygotic twins. Associations were stronger in female monozygotic twins compared with male twins (tetrachoric correlation, 0.60 [95% CI, 0.49-0.70] vs 0.33 [95% CI, 0.13-0.51]; P = .03 in an analysis stratified by sex and zygosity). We estimate that 53% (95% CI, 45%-61%) of susceptibility to diverticular disease results from genetic factors. CONCLUSIONS: Based on a population-based study in Denmark, genetic factors appear to contribute to development of diverticular disease.