Table 1 The four different GORD patient collections used in this study to identify collagen type III alpha I (COL3A1) as a susceptibility gene for GORD

Patient collection		Origin	Usage	Total no of individuals	No of patients with GORD	No of healthy individuals
1	Families	Women’s & Children’s Hospital Adelaide, Australia	Whole-genome linkage analysis	504	237	168
2	Trios	Women’s & Children’s Hospital Adelaide, Australia	Genetic association of candidate genes	1092	364	728
3	Case–control extended Kalixanda	Karolinska Institute, Sweden	Genetic association, replication of findings	741	256	485
4	Case–control EsoNerd	Sahlgrenska Hospital, Sweden	Immunohistochemistry	38	30	8
Summary				2375	887	1389

The family patient collection includes an additional 99 individuals with unknown gastro-oesophageal reflux disease (GORD) status. Affected children of the trios are listed as cases and their parents as controls. In the extended Kalixanda cohort, 98 individuals were diagnosed with both GORD and hiatus hernia (HH). The remaining 131 HH individuals were added from the original Kalixanda cohort,28 producing a separate HH case control material, consisting of 229 cases and the 485 controls.