GSTM1 and cardiomyopathy: The GSTM1 null variant was more prevalent among cases with cardiomyopathy than controls (60.0% vs. 38.0%, p = 0.005): individuals with GSTM1 null genotype had 2.7-times greater risk of developing cardiomyopathy (p = 0.007) compared to those with GSTM1 positive genotype [28].