One previous study in non-obese adolescent girls with PCOS demonstrated that carriers of the GSTM1-null genotype have significantly lower levels of testosterone in comparison to PCOS carriers of the GSTM1-active genotype, which may be related to the ability of GSTM1 to serve as a steroid-binding protein of testosterone [26]. Here, GSTM1 is linked to polycystic ovary syndrome.