In a second study by the same group [74], homozygous carriers of the mutant GSTO2*A424G (N142D) genotype were found to be at a higher risk of transitional cell carcinoma (TCC) of the urinary bladder in comparison with carriers of at least one wild-type GSTO2 allele, and the risk was even higher when such a polymorphism was associated with cigarette smoking. The gene discussed is GSTO2; the disease is transitional cell carcinoma.