137 RESEARCH Open Access Dinucleotide (AC)n Repeat Polymorphism (rs36213840) in the Promoter Region of IL18R1 Gene and Genetic Susceptibility to Severe Malaria Segun I. Oyedeji 1* , Ikenna M. Odoh 2 , Peter U. Bassi 3 , Henrietta O. Awobode 4 1 Molecular Genetics and Parasitology Unit, Department of Animal & Environmental Biology, Federal University Oye-Ekiti, Oye-Ekiti, Nigeria. 2 University Health Centre, Federal University Oye-Ekiti, Oye-Ekiti, Nigeria 3 Department of Pharmacology and Therapeutics, University of Abuja, Abuja, Nigeria. 4 Parasitology Unit, Department of Zoology, University of Ibadan, Ibadan, Nigeria. Abstract Background: Cytokines are key regulators of human immune response to malaria but polymor- phisms within the regulatory or coding regions of their genes may lead to differences in expression lev- els which may consequently influence disease susceptibility. In this study, we characterized an adenine- cytosine (AC) n dinucleotide repeat polymorphism (rs36213840) at the promoter region of the Interleukin 18 Receptor 1 (IL18R1) gene and investigated its association with severe malaria. Methods: We utilised the case-control study design to enrol a total of 207 children including 87 severe malaria cases and 120 asymptomatic controls. DNA was extracted from blood spot on filter paper using QIAamp ® DNA Mini Kit (Qiagen, Hilden, Germany). Genotyping for dinucleotide repeat polymor- phisms was done by PCR and capillary electrophoresis of sequenced products on ABI PRISM ® 3100 DNA sequencer (PE Applied Biosystems). Results: The genotype frequencies of the dinucleotide repeats differed significantly between the two groups (χ 2 = 8.69, P=0.026). We found a significantly higher frequency of the 14bp (AC) 7 allele in severe malaria patients than in asymptomatic controls (odds ratio 1.945, 95% CI: 1.23 - 3.09, P = 0.005) while the frequency of the 16bp (AC) 8 allele was significant higher in the asymptomatic controls than in severe cases (odds ratio 0.431, 95% CI: 0.244 - 0.761, P = 0.004). Conclusion: Results of this suggest that the 14bp (AC) 7 dinucleotide repeats might be a genetic risk factor for susceptibility to severe malaria while the 16bp (AC) 8 dinucleotide repeats might be a protec- tive factor against severe malaria Keywords: Dinucleotide repeat polymorphism, Malaria, Microsatellite, Interleukin 18 receptor, Nigeria Oyedeji et al Pan African Journal of Life Sciences (2020): 4(3): 137-145 Pan African Journal of Life Sciences Volume 4 (Issue 3), November 2020 *Correspondence should be addressed to Segun I. Oyedeji: segun.oyedeji@fuoye.edu.ng; segun.oyedeji@daad-alumni.de Received 9th November 2020; Revised 28th November 2020; Accepted 29th November 2020 © 2020 Oyedeji et al. Licensee Pan African Journal of Life Sciences. This is an Open Access article distributed under the terms of the Creative commons Attribution License (https://creativecommons.org/licenses/BY/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. www.pajols.org Online ISSN:2672-5924 Publication of Faculty of Basic Medical Sciences, Ladoke Akintola University of Technology, Ogbomoso DOI: 10.36108/pajols/0202/40(0350)