Table 1.

Familial aggregation studies

Authors (Year)	Number of IBS patients	Conclusion
Whorwell et al[3] (1986)	100	Significant number of IBS patient had another family member with IBS
Levy et al[4] (2000)	373	Children of parents with IBS made more visits for gastrointestinal symptoms
Locke et al[5] (2000)	643	People with functional gastrointestinal disorders had higher odds of reporting a relative with similar symptoms
Kalantar et al[6] (2003)	181	IBS prevalence was higher among IBS patients' relatives
Saito et al[7] (2008)	50	Statistically higher percentage of IBS patients’ relatives had IBS
Saito et al[8] (2010)	477	50% of IBS patients had at least another relative with IBS
Waehrens et al[9] (2015)	51952	Increased risk of IBS among first, second and third degree relatives of IBS patients

IBS: Irritable bowel syndrome.