DOI: https://doi.org/10.53350/pjmhs22164926 ORIGINAL ARTICLE 926 P J M H S Vol. 16, No. 04, APR 2022 The Polymorphism Study of LEP and LEPR Genes in Association of its Serum Level in Iraqi Patients with Type 2 Diabetic NAWFAL HUSSEIN AMHE 1 , FAWZI HASSAN ZAYR AL-FAHDAWI 2 , ALI GHEISARZADEH 3 , A.A HATAMNIA 4 1 Bacteriology in alazeziah hospital Iraq 2 Department of Chemistry faculty of Medicine / Wasit University / Iraq. 3,4 Faculty of Basic Sciences Cellular and Molecular Biology/ Ilam university /Iran Correspondence to: Nawfal Hussein Amhe, Email: nofelhossinamhi@Gmail.com ABSTRACT Background: Diabetes is a major cause of mortality worldwide. There are several types of diabetes, with type 2 diabetes mellitus (T2DM) being the most common. Many factors, including environmental and genetic factors, are involved in the etiology of the disease. Numerous studies have reported the role of genetic polymorphisms in the initiation and development of T2DM. Aim of study to investigate the prevalence of single nucleotide polymorphisms in LEP gene (LEP 3′UTR A/C, −2548 G/A) and LEPR (K109R and Q223R) and their association with Leptin level and obesity Methods: Here we recruited 150 patients with T2DM and 150 normal individuals. Genotyping was performed using polymerase chain reaction‐restriction fragment length polymorphism, BMI was calculated, and Leptin level was measured by ELISA. The polymorphism study was performed At Leptin -2548G/A and Leptin receptor LEPR Q223R. Statistical analyses were performed by spss19.0. Results: Our data showed that there was a significant difference between BMI, HbA1c, Cholesterol, TG, HDL, LDL and Leptin level in T2DM and normal group, however there was no significant difference in gender of all individuals in two groups of T2DM and normal groups. The G-allele frequency was found to be significantly different between T2DM and control groups. In addition, the genotypic and allele frequencies of Leptin receptor LEPR Q223 Polymorphism in the study individuals have been presenteted. The Q-allele frequency was found to have no significant difference between T2DM and control groups. Our data clearly indicated that HbA1c significantly related with BMI. Similarly cholesterol level significantly related to BMI and HbA1c. There was a similar pattern between other parameters. However there were no significant relationship between HDL and other lipid profile. Moreover, the concentration of Leptin was 5.74± 1.27, 5.67± 1.24 And 4.09 ± 1.44 For genotypes of QQ, QR and RR, respectively. However there was no significant difference in normal group. Conclusion: We found a significant association between the LEPR gene polymorphism and increased T2DM risk in the Iraqi population. Iraqi carriers of the G allele of LEPR gene polymorphism may be more susceptible to T2DM. Keywords: Leptin, Leptin Receptor, Polymorphism, Type 2 Diabetes INTRODUCTION The diabetes classification includes a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion or insulin action. Such a defect increases the risk of cardiovascular disease, kidney failure, blindness, neuropathy and peripheral circulatory disease. It is estimated that diabetic patients will increase to 592 million by 2035 [1]. Type 2 diabetes mellitus (T2DM) accounts for more than 90% of diabetes cases and arises from complex interactions between environmental and genetic factors [2]. One such attractive and popular Single Nucleotide Polymorphism (SNP) candidate for obesity is the gene coding for leptin receptor. The leptin receptor gene polymorphism plays an important role in obesity and type 2 diabetes. But the role of this polymorphism is not yet studied in Iraqi population[3]. Hence, the study focused to explore the association of leptin and its receptor polymorphisms and its effects on leptin level in type 2 diabetes in both diabetic and non-diabetic subjects recruited from the local population of Iraq. Obesity is a common condition in industrialized societies and is increasing rapidly. Its etiology is complex and results from combined effects of genes, environment, lifestyle, and their interactions. Obesity has become a major issue because of its links to type 2 diabetes, hypertension, dyslipidemia, and insulin resistance syndrome[4]. The strength of the link between obesity and specific conditions varies. One of the strongest is the link with type 2 diabetes, which is primarily characterized by insulin resistance. Excess weight is the reason behind 64% of cases of diabetes in men and 77% in women[5]..About 118 candidate genes are so far associated with obesity. Some of the important candidate genes involved in causing obesity are the genes encoding leptin (LEP), leptin receptor (LEPR), melano cortin 4 receptor (MC4R), adiponectin (ADIPOQ), corticotrophin releasing hormone1 (CRHR1), prohormone convertase1 (PC1), pro-opiomelanocortin (POMC), and resistin (RETN)[6]. Among them, leptin and its receptor play the central role. Leptin, encoded by the obesity (LEP) gene, is expressed mainly in adipocytes. Their levels are highly dependent on presence of fats in the cell. It is shown to regulate satiety, energy expenditure, neuroendocrine function, and reproductive competence. The biologic activities of leptin on target tissues are carried out through selective binding to a specific receptor, LEPR. LEPR maps in humans to the 1p31 chromosome and has at least five isoforms. The structure of the leptin receptor is similar to that of the helical cytokine receptor (class I). Leptin receptors form homodimers, which are capable of activating Janus kinases. The Janus kinase is then able to start activators of transcription. Leptin signaling via the Janus kinases and activation of transcription system is largely associated with the long form (LEPR1) of leptin receptor [7]. Studies performed on mice showed that the LEPR1 is important for transmitting the leptin signal to the cells and is located predominantly in the hypothalamus and not in other tissues. However, the short forms are expressed throughout the body, especially in the kidney, lungs, and choroid plexus. Several polymorphisms are commonly occurring in LEPR gene, which cause either synonymous or non synonymous substitutions. The role of homozygosity for inactivating mutations of the leptin receptor (LEPR) in producing extreme obesity syndromes in laboratory animals is established[8]. Additionally, a small number of extremely obese humans from consanguineous pedigrees have been identified, who are obese due to homozygosity for inactivating mutations of LEPR. Heterozygosity for LEPR mutations in mice and rats also results in increase in fat stores[9,10]. The question of whether more common polymorphisms of the LEPR gene confer increased susceptibility to obesity and its associated morbid disorder type 2 diabetes remains open in Iraqi population. Leptin is an endocrine hormone and a member of the long-chain helical cytokine family. It has several effects such as regulating food intake, energy expenditure, body weight and immune responses. Leptin effects are mediated by its receptor, which is located in the central nervous system and other tissues, including adipocytes and endothelial cells[4]. To date many studies showed that Leptin and Leptin receptor are potentially related to the pathophysiology of Type 2 Diabetes. But there is no evidence to evaluate polymorphism of Leptin and Leptin