The other showed interactions between the SE and the null genotype of glutathione S-transferase Mu 1 (GSTM1) in the anti cyclic citrullinated peptide positive (anti-CCP+) patients.
In both assays, the absence of the PCR product was indicative of the null genotype; these assays do not distinguish between heterozygous or homozygous wildtype genotypes.
There was a significant association between the GSTT1 NULL genotype and dermatological toxicity; 43% of these patients experienced severe dermatological toxicity, compared with 19% of the patients without the NULL genotype (P=0.040, Fisher's exact test).
In general, mean percent mortalities for the null genotypes were higher than genotypes with favorable alleles.
22– 25 However, after accounting for the presence of COPD, the association between the GSTM1 null genotype and lung cancer alone was considerably weaker (OR 1.11).
The association between the GSTM1 null genotype and asthma development is not well established in the current literature.
Analysis of the 703 patients of the VARA collection showed additive interaction between the GSTM1 null genotype and SE when comparisons of the anti-CCP+ with the anti-CCP− patients were made [ 23].
In turn, interaction analysis between the GSTM1 null genotype and the SE was performed as described by Mikuls et al. [ 23].
The alternative approaches for analysis of the interaction included interchanging the analyses and other complementary tests that is, testing the interactions used by Briggs et al. for departure from additivity and testing the relationship between the GSTM1 null genotype and SE as a multiplicative interaction.
In a crude data analysis, a positive association was detected between the filaggrin null genotype and, respectively, subjects from the general population who reported diabetes (p=0.04) and patients with established type 2 diabetes (p=0.073).
