Table 1

Patient characteristics, prevalence of SLC6A4, α2C Del 322–325, and α2A −1291 (C→G) polymorphisms, and mean somatic score (SoSC) in 276 patients with lower functional gastrointestinal disorders (FGID) and 120 healthy controls

ControlsLiterature controls* (%)All Lower FGID PatientsIBS-CIBS-DIBS-AltCAP
SoSC, mean somatic symptom score (mean often and mean bothersome scores for 16 symptom “items”). Each “item” is on based on a scale of 0–4.
Lower FGID group comprises the four groups: irritable bowel syndrome with predominant constipation (IBS-C), irritable bowel syndrome with predominant diarrhoea (IBS-D), irritable bowel syndrome with alternating bowel function (IBS-Alt), and chronic abdominal pain (CAP).
*Genotype frequencies for controls are from: Serretti and colleagues,49 Small and colleagues,46 and Tsai and colleagues.50
N120276901283820
Age (mean, range)36 (18–72)49 (18–82)52 (23–82)47 (18–77)47 (18–69)47 (26–78)
Sex (n (% female))95 (79)226 (82)83 (92)98 (77)30 (79)15 (75)
SoSC (mean (SD))0.31 (0.31)0.9 (0.6)0.89 (0.57)0.83 (0.55)0.93 (0.65)0.84 (0.62)
Caucasian (n (%))107 (89)267 (97)86 (96)124 (97)37 (97)20 (100)
SLC6A4
    Wild-type (%)31363640324235
    Heterozygous (%)49474643484545
    Homozygous polymorphism (%)20161817201320
    Any polymorphism (%)69636460685865
α2C Del 322–325
    Wild-type (%)92948985918695
    Heterozygous (%)649117115
    Homozygous polymorphism (%)2224230
    Any polymorphism (%)8611159145
α2A −1291 (C→G)
    Wild-type(%)57485245555355
    Heterozygous (%)36434347394745
    Homozygous polymorphism(%)7858600
    Any polymorphism (%)43514855454745