Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 59 3 2021 03 13 133 141 Raziye Karamikhah Department of Clinical Pharmacy, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran Negar Azarpira Transplant Research Center, Shiraz University of Medical Sciences, Shiraz, Iran Soheila Zareifar Hematology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran Ali Dehshari Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran Soha Namazi Department of Clinical Pharmacy, School of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran Mohammad Hossein Anbardar Department of Pathology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran Iman Karimzade Department of Clinical Pharmacy, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran 2020 06 21 2020 10 23 - Methotrexate (MTX) is the main drug for the treatment of childhood acute lymphoblastic leukemia (ALL). ABCG2 pump is the main transporter of MTX on BBB. Our aim was to investigate the possible relationship between three polymorphisms of the ABCG2 gene, and isolated CNS relapses in Iranian children with ALL receiving high dose MTX. Genotyping of three polymorphisms of the ABCG2 gene, including G34A, C376T, and C421A, was performed by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method for 56 patients. A high frequency of C376T CT genotype was observed among the patients. There was no significant association between C376T and C421 and isolated CNS relapse (P>0.05). C376T and C421A polymorphisms are not associated with isolated CNS relapse in childhood ALL. https://acta.tums.ac.ir/index.php/acta/article/view/8560