Our findings of a high diagnostic yield in patients with previous overt OGIB may be related to characteristics of the tested population, including a high proportion of patients on ongoing treatments potentially associated with SB bleeding (66%), requiring blood transfusions (86%) [2] or with severe anaemia (GROUP B: median of the lowest Hb levels 7.6 g/dL)[1, 13]. This evidence concerns the gene GSTM1 and anemia.