Distribution of E23K Genotypes in Diabetic and Non-Diabetic Subjects in Port Harcourt metropolis, Nigeria.

Abstract
This study examined the distribution of the E23K allele variant of the KCNJ11 gene in type 2 diabetes mellitus and non- diabetics in a Nigerian population. The E23K polymorphism of the KCNJ11 gene results from a substitution of the amino acid lysine to glutamate at codon 23. This alteration causes a critical inhibition of glucose-induced insulin secretion thereby resulting in hyperglycaemia. Hundred consenting Nigerian adults (73 diabetics and 27 non-diabetic subjects) aged at least 40 participated in this study. Genotyping was carried out with the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique using BanII restriction digestion enzyme. The restriction fragments were then electrophoresed on DNA grade agarose gel and the bands visualised using a UV transilluminator. The genotypes identified are the EE (150bp band), EK (150bp+178bp bands) and KK (178bp band) genotypes. The KK genotype was preponderant in the diabetic participants (52%) and was followed by the EK genotype (25.9%) while the EE genotype was more in the non-diabetic participants (66.7%). The risks conferred by the different genotypes/allele are as follows: EK (p value = 0.5639; OR = 1.32), EE (p value = 0.000; OR = 0.21), KK (p value = 0.0037; OR = 7.03), K (p value = 0.211; OR = 2.59) and E (p value = 0.0552; OR = O.52). A carrier of the KK genotype is seven times more likely than a non-carrier to develop type 2 diabetes mellitus (p value = 0.0037; 7.03). Only the KK genotype was found to significantly increase the risk of developing type 2 diabetes complications (p value = 0.02; OR = 12.67). The p values of the selected biochemical variables are as follows: leptin = 0.95, fasting blood sugar = 0.15, C-peptide = 0.47, Cystatin C = 0.86, HbA1C = 0.01, insulin = 0.65 and HOMA = 0.65. Of the glycaemic variables analyzed, only HbAlc showed a significant difference between the diabetic and control groups (p value = 0.01) but there was no significant difference in its levels in the different genotypes (p value = 0.64). A significant association between the E23K polymorphism and T2DM was found in the Nigerian population that was studied. The KK genotype of the E23K polymorphism of the KCNJ11 gene is an independent predictor of Type 2 diabetes mellitus.

Keywords
E23K, Polymorphism, Diabetes Type2, Genotype, KCNJ11 gene

Cite this paper
Brown Holy, Enyi Alice Ruhuoma, Davies Tamunoemine, Distribution of E23K Genotypes in Diabetic and Non-Diabetic Subjects in Port Harcourt metropolis, Nigeria. , SCIREA Journal of Clinical Medicine. Volume 6, Issue 3, June 2021 | PP. 129-149. 10.54647/cm32457

References

[ 1 ]	Alsmadi, O., Al-Rubeaan, K., Wakil, S. M., Imtiaz, F., Mohamed, G., Al-Saud, H., Al-Saud, N., Aldaghri, N., Mohammad, S. & Meyer, B.F. (2008). Genetic study of Saudi diabetes (GSSD): significant association of the KCNJ11 E23K polymorphism with type 2 diabetes. Diabetes/Metabolism Research and Review, 24, 137-140. And the risk for severe sulfonylurea-induced hypoglycemia in patients with type 2 diabetes. Hormone and Metabolic Research, 41(5), 387–390.
[ 2 ]	Assman, T.S., Duarte, G.C., Rheinheimer, J., Cruz, L.A., Canani, L.H. & Crispim, D. (2014). The TCF7L2 rs7903146 (C/T) polymorphism is associated with risk to type 2 diabetes mellitus in Southern-Brazil. Brazillian Society of Endocrinology and Metabolism, 58(9), 918-25.
[ 3 ]	Assmann, G., Buono, P., Daniele, A., Della Valle, E., Farinaro, E., Ferns, G. & Misciagna, G. (2014). Functional foods and cardiometabolic diseases: International task force for prevention of cardiometabolic diseases. Nutrition, Metabolism and Cardiovascular Diseases, 24(12), 1272-1300.
[ 4 ]	Chistiakov, D. A., Potapov, V. A., Khodirev, D. S., Shamkhalova, M. S., Shestakova, M. V. & Nosikov, V. V. (2008). The KCNJ11 E23K and ABCC8 exon 31 variants contribute to susceptibility to type 2 diabetes intolerance and altered insulin secretion in a Russian population. Diabetes and Metabolic Syndrome Clinical Research and Review, 2, 185-91.
[ 5 ]	Dupuis, J., Langenberg C., Propenko, I., Saxena, R., Soranzo, N., Jackson, A.U., Wheeler, E., Glazer, N.L., Bouatia-Naji, N., Gloyn, A.L., Lindgren, C.M., Magi, R., Morris, A.P., Randall, J., Johnson, T., Elliot, P., Rybin, D., Thorleifsson, G., Steinthorsdottir, V. & Henneman, P. (2008). New genetic loci implicated in fasting glucose homeostasis and their impact on type 2 diabetes risk. Nature genetics, 42(5), 464
[ 6 ]	El-sisi, A. E., Hegazy, S. K., Metwally, S. S., Wafa, A. M. & Dawood, N. A. (2011). Effect of genetic polymorphisms on the development of secondary failure to sulfonylurea in egyptian patients with type 2 diabetes. Therapeutic Advances in Endocrinology and Metabolism, 2(4), 155–164.
[ 7 ]	Engwa, G. A., Nwalo, F. N., Chiezey, V. O., Unachukwu, M. N., Ojo, O. O. & Ubi, B. E. (2018). Assessment of the Pro12Ala Polymorphism in the PPAR-γ2 Gene among Type 2 Diabetes Patients in a Nigerian Population. Journal of Clinical Medicine, 7 (4), 69-75.
[ 8 ]	Ezzidi, I., Mtiraoui, N., Cauchi, S., Vaillant, E., Dechaume, A., Chaieb, M., Kacem, M.M., Alawi., W.Y., Froguel, P., Mahjoub, T. & Vaxillare, M. (2009). Contribution of type 2 diabetes associated loci in the Arabic population from Tunisia: a case-control study. BMC Medical Genetics, 10, 33.
[ 9 ]	Florez, J. C., Burtt, N., de Bakker, P. I.W., Almgren, P., Tuomi, T., Holmkvist, J., Gaudet, D., Hudson, T.J., Schaffner, S.F., Daly, M.J., Hirschhorn, J.N, Groop, L. & Altshuler, D. (2004). Haplotype structure and genotype-phenotype correlations of the sulfonylurea receptor and the islet ATP-sensitive potassium channel gene region. Diabetes, 53(5), 1360-1368.
[ 10 ]	Florez, J. C., Burtt, N., de Bakker, P. I.W., Almgren, P., Tuomi, T., Holmkvist, J., Gaudet, D., Hudson, T.J., Schaffner, S.F., Daly, M.J., Hirschhorn, J.N, Groop, L. & Altshuler, D. (2004). Haplotype structure and genotype-phenotype correlations of the sulfonylurea receptor and the islet ATP-sensitive potassium channel gene region. Diabetes, 53(5), 1360-1368.
[ 11 ]	Gloyn, A. L, Weedon, M. N., Owen, K. R., Turner, M. J., Knight, B.A., Hitman, G., Walker, M., Levy, J.C., Samson, M., Halford, S., McCarthy, M.I., Hattersley, A.T. & Frayling, T.M. (2003). Large-scale association studies of variants in genes encoding the pancreatic beta-cell KATP channel subunits Kir6.2 (KCNJ11) and SUR1 (ABCC8) confirm that the KCNJ11 E23K variant is associated with type 2 diabetes. Diabetes, 52, 568-572.
[ 12 ]	Gonen, M. S., Arikoglu, H., ErkocKaya, D., Ozdemir, H., Ipecki, S.H., Arslan, A, Kayis, S.A. & Gobbakan, B. (2012). Effects of single nucleotide polymorphisms in KATP channel genes on type 2 diabetes in a Turkish population. Archives of Medical Research, 43(4), 317–323.
[ 13 ]	Grant, S. F., Thorleifsson, G., Reynisdottir, I., Benediktsson, R., Manolescu, A., Sainz, J., Helgason, A., Stefansson, H., Emilsson, V., Helgadottir, A., Styrkarsdottir, U., Magnusson, K.P., Walters, G.B., Palsdottir, T., Jonsdottir, T., Gudmundsdottir, T., Gylfason., A., Saemundsdottir, J., Wilensky, R.L., Reilly, M.P., Rader, D.J., Bagger, Y., Christansen, C., Gudnason, V., Sigurdsson, G., Thorsteinsdottir, U., Gulcher, J.R., Kong, A. & Steffansson, K. (2006) Variant of transcription factor 7-like 2 (TCF7L2) gene confers risk of type 2 diabetes. Nature Genetics, 38, 320–323.
[ 14 ]	Haghvirdizadeh, P., Mohamed, Z., Abdullah, N.A., Haghvirdizadeh, P., Haerian, M.S. & Haerian, B. S. KCNJ11: Genetic Polymorphisms and Risk of Diabetes Mellitus. (2015). Journal of Diabetes Research, 908152.
[ 15 ]	Hamming, K. S. C, Soliman, D., Matemisz, L. C., Niazi, O., Lang, Y., Gloyn, A.L. & Light, P.E. (2009). Coexpression of the type 2 diabetes susceptibility gene variants KCNJ11 E23K and ABCC8 S1369A alter the ATP and sulfonylurea sensitivities of the ATP-sensitive K (+) channel. Diabetes, 58(10), 2419-2424.
[ 16 ]	He, Y.Y, Zhang, R., Shao X.Y., Hu, C., Wang, C.R., Lu, J.X., Bao, Y.Q, Jia, W.P & Xiang, K. S. (2008). Association of KCNJ11 and ABCC8 genetic polymorphisms with response to repaglinide in Chinese diabetic patients. Acta Pharmacologica Sinica, 28 (8), 983–89.
[ 17 ]	Holstein, A., Hahn, M., Stumvoll, M. & Kovacs, P. (2009). The E23K variant of KCNJ11 International Diabetes Federation Atlas. (2017). IDF Diabetes Atlas. 7th ed. International Diabetes Federation, Brussels, Belgium.
[ 18 ]	James, C. Kapoor, R.R., Ismail, D. & Hussain, K. (2009). The genetic basis of congenital hyperinsulinism. Journal of Medical Genetics, 46 (5), 289–99.
[ 19 ]	Javorsky, M., Klimcakova, L., Schroner, Z., Zidzik, J., Babjakova, E., Fabianova, M., Kozarova, M., Tkacova, R, Salagovic, J. & Tkac, I. (2012). KCNJ11 gene E23K variant and therapeutic response to sulfonylureas. European Journal of Internal Medicine, 23(3), 245–249.
[ 20 ]	Khalid, A., Balushi, A., Mahmod, A.H, Ibrahim, A.L. & Mohammed, A.Z. (2014). Glycaemic control among patients with type 2 diabetes at a primary health care centre in Oman. Primary Care Diabetes, 8(3), 239-43.
[ 21 ]	Kocyigit, I., Dortdudak, S., Eroglu, E., Una, A., Sipahioglu, M. H., Berk, V., Tokgoz, B . & Oymak, O. (2013) The E23K polymorphism of the KCNJ11 gene is associated with lower insulin release in patients with Autosomal Dominant Polycystic Kidney Disease Nefrologia, 33(6), 855-8.
[ 22 ]	Koo, B. K., Cho, Y. M., Park, B. L., Cheong, H. S., Shin, H. D., Jang, H. C., Kim, S. Y., Lee, H. K. & Park, K. S. (2007). Polymorphisms of KCNJ11 (Kir6.2 gene) are associated with type 2 diabetes and hypertension in the Korean population. Diabetic Medicine, 24, 178–186.
[ 23 ]	Koo, B. K., Cho, Y. M., Park, B. L., Cheong, H. S., Shin, H. D., Jang, H. C., Kim, S. Y., Lee, H. K. & Park, K. S. (2007). Polymorphisms of KCNJ11 (Kir6.2 gene) are associated with type 2 diabetes and hypertension in the Korean population. Diabetic Medicine, 24, 178–186.
[ 24 ]	Lasram, K., Halim N. B., Hsouna, S., Kefi, R., Arfa, I., Ghazouani, W., Jamoussi, H., Benrahma, H., Ammar, S. B., Bahri, S., Barakat, A., Abid, A. & Abdelhak, S. (2014). Evidence for Association of the E23K Variant of KCNJ11 Gene with Type 2 Diabetes in Tunisian Population: Population-Based Study and Meta-Analysis. Biomedical Research International, 265274.
[ 25 ]	Mori, T., Matsumura, M., Yamada, K., Irie, S., Oshimi, K., Suda, K., Oguri, T. & Ichinoe, M. (1998). Systemic aspergillosis caused by an aflatoxin-producing strain of Aspergillus flavus. Medical Mycology, 36 (2), 107-12.
[ 26 ]	Nanfa, D., Sobngwi, E., Atogho-Tiedeu, Noubiap, J.J.N., Donfack, O.S., Mofo, E.P.M., Guewo-Fokeng, M., Metsadijo, A,N., Ngwa, E.N., Fosso, P.P., Djahemeni, E., Djokam-Dadjeu, R., Evehe, M.S., Aminkeng,F., Mbacham, W.F. & Mbanya, J.C. (2015). Association between the TCF7L2 rs12255372 (G/T) gene polymorphism and type 2 diabetes mellitus in a Cameroonian population: a pilot study. Clinical and Translational Medicine, 4, 17.
[ 27 ]	Nielsen, E. M., Hansen, L., Carstensen, B., Echwald, S. M., Drivsholm, T., Glumer, C., Thorsteinsson, B., Borch-Johnsen, K., Hansen, T. & Pedersen, O. (2003). The E23K variant of Kir6.2 associates with impaired post-OGTT serum insulin response and increased risk of type 2 diabetes. Diabetes, 52, 573-577.
[ 28 ]	Permutt, M., Wasson, J. & Cox, N. (2005). Genetic epidemiology of diabetes. The Journal of Clinical Investigation, 115, 1431-9.
[ 29 ]	Qi, Q., Liang, L., Doria, A., Hu, F. B. & Qi, L. (2012). Genetic predisposition to dyslipidemia and type 2 diabetes risk in two prospective cohorts. Diabetes, 61(3), 745‐52.
[ 30 ]	Rastegari, A., Rabbani, M., Sadeghi, H. M., Imani, E. F., Hasanzadeh, A. & Moazen, F. (2015) Association of KCNJ11 (E23K) gene polymorphism with susceptibility to type 2 diabetes in Iranian patients. Advanced Biomedical Research, 4, 1.
[ 31 ]	Riedel, M.J., Steckley, D.C. & Light, P.E. (2005). Current status of the E23K Kir6.2 polymorphism: implications for type-2 diabetes. Human Genetics, 116(3) 133–45.
[ 32 ]	Sagen, J.V., Raeder, H., Hathout, E., Shehadeh, N., Gudmundsson, K., Baevre, H., Abuelo, D., Phornphutkul, C., Molnes, J., Bell, G.I., Gloyn, A.L., Hattersley, A.T., Molven, A., Sovik, O. & Njoslstad, P.R. (2004). Permanent neonatal diabetes due to mutations in KCNJ11 encoding Kir6.2: patient characteristics and initial response to sulfonylurea therapy. Diabetes, 53(10), 2713–8.
[ 33 ]	Sakamoto, Y., Inoue, H., Keshavarz, P., Miyawaki, K., Yamaguchi, Y., Moritani, M., Kunika, K., Nakamura, N., Yoshikawa, T., Yasui, N., Shiota, H., Tanahashi, T. & Itakura, M. (2007). SNPs in the KCNJ11-ABCC8 gene locus are associated with type 2 diabetes and blood pressure levels in the Japanese population. Journal of Human Genetics, 52, 781–793.
[ 34 ]	Sandhu, R., Rai, S. K., Rai, G., Attri, H. & Bawa, V. (2018). Assessment of genetic diversity among various genotypes of Brassisa Napus L. using molecular markers. Chemical Science Review and Letters, 7(26), 540-545.
[ 35 ]	Saxena, R., Voight, B. F., Lyssenko, V., Burtt, N. P., de Bakker, P. I. W., Chen, H., Roix, J.J., Kaithiresan, S., Hirschhorn, J.N., Daly, M.J., Hughes, T.E., Groop, L., Altshuler, D., Almgren, P., Florez, J.C., Meyer, J., Ardlie, K., Bostrom, K.B., Isooma, B., Lettre, G., Linbald., U., Lyon., H.N., Melander, O., Newton-Cheh, C., Nilsson, P., Orho-Melander, M., Rastam, L., Speliotes, E.K., Taskinen, M.R., Tuomi, T., Guiducci, C., Berglund., A., Carlson., J., Gianninny, L., Hackettet, R., Hall, L., Holmkvist, J., Laurila, E., Sjogren, M., Sterner, M., Surti, A., Svensson, M., Svensson, M., Tewhey, R, Blumenstiel, B., Parkin, M, Defelice, M., Barry., R., Brodeur, W., Camarata., J., Chia, N., Fava, M., Gibbons, J., Handsaker, B., Healy, C., Nguyen, K., Gates, C., Sougnez, C., Gage, D., Nizzari. M., Gabriel., S.B., Chirn, G.W., Ma, Q., Parikh, H., Richardson., D, Ricke, D. & Purcel, S. (2007). Genome-wide association analysis identifies loci for type 2 diabetes and triglyceride levels. Science, 316(5829), 1331-6.
[ 36 ]	Scott, L. J., Mohlke, K. L., Bonnycastle, L. L., Willer, C. J., Li, Y., Duren, W. L., Erdos, M. R., Stringham, H. M., Chines, P. S., Jackson, A. U., Prokunina-Olsson, L., Ding, C.J., Swift, A.J., Narisu, N., Hu, T., Pruim, R., Xiao, R., Li, X.Y., Conneely, K.N, Riebow, N.L., Sprau., A.G., Tong, M., White, P.P., Hetrick, K.N., Barnhart, M.W., Bark, C.W., Goldstein, J.L.,Watkins, L., Xiang, F., Saramies, J., Buchanan, T.A., Watanabe, R.M., Valle, T.T., Kinnunen, L., Abecasis, GR., Pugh, E.W., Doheny, K,F., Boehnke, R.N., Tuomilehto, J., Collins, F.S. & Boehnke, M. (2007). A genome-wide association study of type 2 diabetes in Finns detects multiple susceptibility variants. Science, 316, 1341-1345.
[ 37 ]	Shaat, N., Ekelund, M., Lernmark, A., Ivarsson, S., Almgren, P., Berntorp, K. & Groop, L. (2005). Association of the E23K polymorphism in the KCNJ11 gene with gestational diabetes mellitus. Diabetologia, 48, 2544-51.
[ 38 ]	Souza, S. W., Alcazar, I. P., Arakaki, P. A., Santos-Weiss, I. C. R., Alberton, D., Pitcheth, G. & Rego, F.G.M. (2017). Polymorphism E23K (rs5219) in the KCNJ11 gene in Euro-Brazilian subjects with type 1 and 2 diabetes. Genetics and Molecular Research, 16, 2.
[ 39 ]	Sparso, T., Andersen, G., Albrechtsen, A., Jorgensen, T., Borch-Johnsen, K., Sandbaek, A., Lauritzen, T., Wasson, J., Permutt, M.A., Glaser, B., Madsbad, S., Pedersen, O. & Hansen, T. (2008) Impact of polymorphisms in WFS1 on prediabetic phenotypes in a population based sample of middle-aged people with normal and abnormal glucose regulation. Diabetologia, 51, 1646–52.
[ 40 ]	Taber, J. M., Klein, W. M. P., Ferrer, R. A., Lewis, K. L., Biesecker, L. G. & Biesecker, B. B. (2015). Dispositional optimism and perceived risk interact to predict intentions to learn genome sequencing results. Health Psychology, 34(7), 718–28.
[ 41 ]	Vimaleswaran, K.S. & Loos, R.J. (2010). Progress in the genetics of common obesity and type 2 diabetes. Expert Reviews in Molecular Medicine, 12, e7.
[ 42 ]	Yang, L., Juntti-Berggren, L., Kohler, M. & Berggren, P.O. (2007). Glucose recruits K(ATP) channels via non-insulin-containing dense-core granules. Cell Metabolism, 6(3), 217-28.
[ 43 ]	Zadhoush, F., Sadeghi, M. & Pourfarzam, M. (2015). Biochemical changes in blood of type 2 diabetes with and without metabolic syndrome and their association with metabolic syndrome components. Journal of Research in Medical Sciences, 20(8), 763-770.
[ 44 ]	Zhou, D., Zhang, D., Liu, Y., Zhao, T., Chen, Z., Liu, Z., Yu, L, Zhang, .Z.F., Xu, H. & He, L. (2009). The E23K variation in the KCNJ11 gene is associated with type 2 diabetes in Chinese and East Asian population. Journal of Human Genetics, 54, 433-435.