BgSel has been identified in Biomphalaria glabrata as a candidate adhesion molecule exhibiting both an Ig-like domain and a carbohydrate recognition domain showing similarities with the l domain of C-type lectins. As susceptibility or resistance of B. glabrata to the trematode Echinostoma caproni correlates with a differential hemocytic adhesive behavior, we investigated the expression of BgSel in snails selected for their susceptibility or resistance. Semi-quantitative RT-PCR analysis of BgSel expression revealed that (i) BgSel expression level was high in susceptible snails and almost undetectable in resistant snails, and that (ii) exposure to the parasite did not affect the expression level of BgSel in either strain. In order to validate this apparent association between low levels of BgSel expression and resistance, we used Real-Time PCR to characterize the relative expression of BgSel in individual snails segregating for susceptibility/resistance. Results established that differential expression of BgSel represents a functional strain marker, but is not a marker of resistance/susceptibility. It is suggested that this correlative approach may be a rapid and efficient alternative to complete functional analyses, and may facilitate the validation of candidate transcripts potentially identified through the numerous differential analyses of animal transcriptomes.