CD is a complex non-Mendelian trait. The present study shows that the positive likelihood ratio (LR+) value for the subjects carrying SNP8^T/T to develop CD was 1.1, which shows that this variant of CNR1 exerts a minor effect on the vulnerability to CD. This could explain why single locus analysis of this SNP in the case-control sample did not show a significant association with CD. Alternatively, the interaction model may more accurately reflect the genetic effects underpinning CD. The present study showed that the LR+ value for interaction between SNP3^G+ and SNP8^T/T was 1.4, considerably higher than that for either SNP3^G+ or SNP8^T/T alone, showing that the interaction analysis is more powerful than the single locus analysis in detecting the association of CNR1 with CD.
