429 Vol. 71, No. 2-A, February 2021 Introduction The host-defense mechanism is integral in terms of preventing the dysfunctions of physiological processes. In our ever-changing environment, the body responds to the aberrant stimuli, such as infections, trauma and injury, by releasing proteins in plasma, such as acute phase proteins (APP). The APP is a class of protein which is released and regulated in response to any stressful encounter or change in the homeostasis of the body consisting of a large group of plasma proteins. C-reactive protein (CRP), an important member of APP proteins, is one of the blood test markers used as a diagnostic tool in a clinical setting to evaluate the inflammatory response as it is increased in a wide array of pathologies, such as viral and bacterial infections, inflammation, diabetes mellitus (DM), cardiovascular disease (CVD), cancers and numerous pathophysiological insults. CRP serves as a predictor of inflammatory response in preventing microorganisms and their toxins to cause damage, triggering complement system, trapping free haemoglobins, and plays a role in regulating the host’s immune response. 1 During an inflammatory condition or infection, CRP is released by hepatocytes in response to the release of cytokines, like interleukin-1 (IL-1), IL-6 and tumour necrosis factor alpha (TNFα) by antigen presenting cells, such as macrophages, lymphocytes and monocytes. 2 Researchers initially discovered CRP and showed its ability to react with the cell wall component referred to as fraction ‘C’ of Strep pneumococci, which, upon immunological analysis, showed strong precipitation. 3 Thereafter, it was shown that CRP serum level predominantly increases during the infections, tissue injuries and various pathologies. This makes CRP a potent clinical marker in various inflammatory processes. 4 Some studies showed that increased CRP level may provide protection against invading microorganisms and can limit the tissue damage by recognising the phosphorylcholine moieties and can opsonise microbial pathogen. 5 CRP is encoded by the CRP gene, which is present on chromosome 1 at q arm with the cytogenetic band at position 23.2. The size of the gene is 2kb, or 2,321 bases. The production of CRP is solely regulated at the transcriptional level in the presence of specific transcriptional factors, including CCAAT/enhancer- binding protein (C/EBP) family members C/EBP beta (β) and C/EBP gamma (g). 6,7 CRP is a polymorphic gene which is known to have polymorphism in multiple regions, like promoter, exonic, intronic and three prime untranslated regions (3´UTRs). Recent studies among diverse population have shown a causal correlation between CRP gene single nucleotide polymorphisms (SNPs) and susceptibility of different diseases, such as Diabetes Mellitus (DM), cancer, cirrhosis, atherosclerosis, cardiac diseases, and systemic lupus erythematosus (SLE). 8,9 However, a link between serum CRP levels and SNPs in viral infection, such as RESEARCH ARTICLE Correlation of C-reactive protein levels, gene polymorphism and platelets count in Dengue infection Sana Shamshad 1 , Sara Khan 2 , Ghazala Kaukab Raja 3 , Muhammad Sheeraz Ahmad 4 , Muhammad Javaid Asad 5 , Tayyaba Zainab 6 Abstract Objective: To determine the correlation of polymorphism in C-reactive protein gene with variation in serum levels in dengue patients. Methods: The cross-sectional study was conducted at Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, Pakistan, from October 2017 to October 2018, and comprised blood samples from dengue patients which were used to measure the serum levels of C-reactive protein. Deoxyribonucleic acid extraction followed by tetra amplification-refractory mutation system polymerase chain reaction was used to analyse the genotype variation T>G for single nucleotide polymorphism rs199953854 using allele-specific primers. Correlation of serum C-reactive protein levels with the C-reactive protein polymorphism in dengue patients was explored. Data was analysed using SPSS 21. Results: Of the 200 patients, 108(54%) had very high C-reactive protein levels, 48(24%) had levels slightly higher than the upper limit, 14(7%) had low and 30(15%) had normal levels. Also, 162(81%) patients had low platelets count. Amplification of only T alleles was noted. Conclusion: C-reactive protein levels were found to be increased with suppressed platelets count in dengue patients. Single nucleotide polymorphism rs199953854 appeared to have no polymorphism. Keywords: C-reactive protein, Dengue infection, rs199953854, CRP polymorphism. (JPMA 71: 429; 2021) DOI: https://doi.org/10.47391/JPMA.326 1,3-6 National Center of Industrial Biotechnology, (PMAS) Arid Agriculture University, Rawalpindi, Pakistan; 2 Rawalpindi Medical University, Rawalpindi, Pakistan. Correspondence: Tayyaba Zainab. e-mail: tayyaba.zainab@uaar.edu.pk