As there are known examples in an imprinted setting where the paternal and maternal alleles interact15, we tested rs2334499 for an interactive effect. This test was not significant (P > 0.4, Supplementary Information) indicating that the multiplicative model provides an adequate fit. Specifically, compared to CT (first allele paternal, second allele maternal), CC, TT and TC have relative risks of 1.17, 1.35 and 1.57 respectively.
