A genetic contribution has been proposed for irritable bowel syndrome (IBS) and gastro-oesophageal reflux disease (GERD), but it is controversial and no twin data exist for dyspepsia.
Dr A. Lembo and colleagues from the USA and Sydney, Australia, conducted an experiment to determine the relative contribution of genetic factors in IBS, GERD and dyspepsia (upper abdominal pain).
They selected a total of 986 pairs of twins (from an initial mail-out response of 51%) and both members completed validated symptom and psychological questionnaires.
|GERD and IBS may be mediated by the hereditability of anxiety and depression|
| Alimentary Pharmacology & Therapeutics |
There were 481 monozygotic pairs [mean (s.d.) age 53 ± 5.8 years] and 505 dizygotic pairs (mean age 54 ± 5.6 years).
Prevalence of IBS, dyspepsia and GERD was found to be 12%, 10% and 20%, respectively.
Polychoric correlation for monozygotic twins for IBS (0.47) and GERD (0.44) were both substantially larger than those for dizygotic twins (0.17 and −0.37, respectively).
Polychoric correlation was slightly lower in monozygotic than dizygotic twins for dyspepsia.
Genetic modeling confirmed the independent additive genetic effects in GERD and IBS but not dyspepsia.
Estimates of genetic variance were 22% for IBS, 13% for GERD and 0% for dyspepsia, but adjusting for anxiety and depression removed the statistical significance for IBS and GERD.
Dr Lembo and team concluded that, "There is a genetic contribution to GERD and IBS but not dyspepsia; this may be mediated by the hereditability of anxiety and depression".