HPGDS and tuberculosis: In addition, deficiency of glutathione S-transferases (GSTs) activity due to a homozygous null genotype of either or both of the GSTM1 and GSTT1 genes can influence susceptibility to INH hepatotoxicity and appears to be associated with a high incidence of hepatotoxic effects of anti-TB therapy.60, 61, 62 Deficiency of superoxide dismutase (SOD) may also increase the risk of INH hepatoxicity.63