The majority of study participants were zonulin-producers; 32 of 36 (89%) of the NCWS cohort, 34 of 37 (92%) of patients with untreated coeliac disease, 19 of 20 (95%) patients with ulcerative colitis, and 46 of 49 (94%) healthy individuals had the Hp2-1 or Hp2-2 phenotype (Table 1). Here, HP is linked to celiac disease.