It has been reported that glutathione S-Transferase Mu 1 (GSTM1) null genotype is likely to be responsible for susceptibility to Cd toxicity in RR-MS patients, particularly in patients with a smoking habit, therefore, we advise that future studies should consider the genotype feature of the patient to define the exact reason of higher Cd levels in RR-MS patients (Aliomrani et al., 2017[3]). Here, GSTM1 is linked to myeloid sarcoma.