This review found a higher risk of asthma for people with both GSTM1 null and GSTT1 null genotypes (OR 2.15, 95%CI 1.21, 3.71) compared to those with two non-null genotypes, but no evidence of an association in those with only one null GSTM1 or GSTT1 gene (Minelli et al., 2010). The gene discussed is GSTM1; the disease is asthma.