Are the CYP2D6*G and MDR1, 3435T Alleles Associated with the Risk of Ulcerative Colitis in Iranian Population?

The paper published by Lotfi et al1 concerning the public health of the Iranian population explores three polymorphisms of genes that code for proteins that contribute to drug-related treatment of ulcerative colitis (UC): CYP2D6, NAT2 and MDR1. We analyzed the data shown in Tables 2 and 3 of both cases and control subjects, using the Epi InfoOpen program of the CDC. We found that the allele CYP2D6* 4 G variant is associated as a protective factor with the development of UC with χ2= 3.812, df = 1, P = 0.05088, odds ratio (OR) = 0.8163 (95% CI= 0.6776–0.9834) (see Table 1), while the A allele was associated as a risk factor; χ2 = 3.812, df = 1, P = 0.05088, o‎r = 1.2251 (95% CI = 1.017–1.476). While Lotfi et al have only reported the allele A as a risk factor (OR = 1.56, P = 0.0471), both results are important. Evaluating the effect of variation in a gene on a disease like UC can be achieved under five inheritance genetic models; dominant, recessive, co-dominant, overdominant, and paradominant, which Lotfi et al1 do not present completely in the text.2-5 Table 2 only shows data for a co-dominant (AG vs. GG or AA vs. GG) and a recessive (AA+AG vs. GG) model. Therefore, we analyzed the distribution of genotypes by these five models for the polymorphisms CYP2D6 *A/G and N-acetyltransferase-2 (NAT2*7), A/G, but we only found a trend which shows that lack of two copies of G modifies the risk, P = 0.099552 through the recessive model. Consistent with the results presented by Lotfi et al, no other epidemiological model was found with a trend or significant values.