Background: The human murine double minute 2 (MDM2), an oncoprotein, is the major negative regulator of P53.

Objectives: The purpose of this study was to evaluate the impact of 40-bp insertion/deletion (ins/del) polymorphism in the promoter of MDM2 and vulnerability to childhood acute lymphocytic leukemia (ALL) in a sample of Iranian population.

Patients and Methods: This case-control study was performed on 75 children diagnosed with ALL and 115 healthy children. The 40-bp ins/del variant was determined by using the polymerase chain reaction method.

Results: Our findings showed that neither the overall chi-square comparison of cases and control subjects (X² = 1.13, P = 0.569) nor the logistic regression analysis (codominant: OR = 1.29, 95% CI = 0.59-2.14, P = 0.745, ins/del vs. ins/ins; OR = 1.59, 95% CI = 0.59-3.77, P = 0.372, del/del vs. ins/ins, dominant: OR = 1.25, 95% CI = 0.69-2.23, P = 0.552, ins/del + del/del vs. ins/ins and recessive: OR = 1.51, 95% CI = 0.67-3.43, P = 0.395, del/del vs. ins/ins + ins/del) indicated any association between MDM2 ins/del and ALL in our population.

Conclusions: Our findings indicated that MDM2 40-bp ins/del polymorphism was not associated with ALL in our Iranian population. Further studies with larger sample sizes and diverse ethnicities are required to verify our findings.