Multiple myeloma (MM) is a hematological malignancy characterized by the presence of abnormal plasma cells. It is associated with anemia, bone lesions and renal dysfunction. Immunomodulatory drugs (IMiDs) are commonly used in MM treatment. Recent studies indicate that their therapeutic effect is caused by binding to cereblon (CRBN), which in turn causes the degradation of 2 important immune cell regulatory factors, IKZF1 and IKZF3. These are necessary for the anti-myeloma effect of IMiDs. Their expression level has been shown to affect MM survival and response to treatment. Potentially important single-nucleotide polymorphisms (SNPs) in the genes coding for IKZF1 and IKZF3 have been identified, but they have not been analyzed in MM patients before.