Skip to main content

The Pro12Ala polymorphism in the PPAR­γ2 gene is not associated with an increased risk of NAFLD in Iranian patients with type 2 diabetes mellitus

Abstract

Background

The peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that belong to the nuclear hormone receptor superfamily. Several studies have demonstrated a significant association between Pro12Ala polymorphism of the PPAR­γ2 gene and metabolic disorders. Therefore, this study aimed to evaluate the association of Pro12Ala polymorphism with increased risk of NAFLD in Iranian patients with type 2 diabetes mellitus.

Methods

This cross-sectional study was performed on 145 healthy control subjects and 145 NAFLD patients with a history of type 2 diabetes. Pro12Ala polymorphism genotyping was performed using PCR–restriction fragment length polymorphism (RFLP) technique with the Bs1I restriction enzyme.

Results

Our results demonstrated that CC and GG genotypes of Pro12Ala were found in the participants, but there was no statistically significant difference between NAFLD patients and healthy controls (P = 0.64 and χ2 = 0.21).

Conclusion

This study suggests that Pro12Ala polymorphism of the PPAR­γ2 gene cannot be considered as a risk factor for NAFLD in the Iranian population.

Introduction

Nonalcoholic fatty liver disease (NAFLD) is one of the most prevalent forms of progressive liver disease, which is characterized by obesity, dyslipidemia, type 2 diabetes mellitus (T2DM), hypercholesterolemia, hypertension, insulin resistance, cirrhosis, liver failure and hepatocellular carcinoma [1,2,3]. NAFLD is highly prevalent in T2DM and the prevalence of NAFLD in obese adults with T2DM has been estimated to be greater than 70%. The most important treatment method of NAFLD is to increase insulin sensitivity by lifestyle changes [2,3,4,5,6,7,8,9,10]. Epidemiological, familial, and twin studies have suggested that genetic background and environmental factors play important roles in the pathogenesis of NAFLD as multifactorial diseases [8,9,10,11,12,13,14,15,16].

The peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors which belong to the nuclear hormone receptor superfamily and consist of three subtypes, each of them encoded by different genes: PPARα (NR1C1), PPARγ (NR1C3) and PPARδ (NP1C2) [3, 16,17,18]. The PPARγ receptor plays a key role in the regulation of adipocyte-specific genes, lipid metabolism, glucose homeostasis, insulin sensitivity and blood pressure [2, 16, 19, 20]. The human PPARγ gene, located on chromosome 3p25, has nine exons (A1, A2, B, exons 1–6 from 5′ to 3′ direction), and its protein product has three isoforms, PPARγ1, PPAR-γ2 and PPARγ3, which are produced by mRNA alternative splicing of PPARγ [4, 20, 21]. Among them, the PPAR-γ2 isoform is expressed predominantly in the adipose tissue, where it plays an important role in regulating adipogenic differentiation and as a mediator of insulin sensitivity [20, 22,23,24,25]. The single nucleotide polymorphisms (SNPs) of the PPAR-γ2 gene have been shown to be associated with susceptibility to several metabolic disorders and many studies have shown a strong relationship between this gene and the occurrence of T2DM in many populations [9, 10, 26, 27]. The polymorphism rs1801282 (c.34C > G) on codon 12 of exon B of the PPAR-γ2 gene, which leads to the substitution of proline with alanine (Pro12Ala), was found to be associated with higher insulin sensitivity, lower body mass index (BMI), decreased risk of T2DM and diabetic nephropathy [28,29,30,31,32]. Several investigations have shown that there is an association between this polymorphism and increased risk of metabolic disorders in various populations. However, published results on the genetic associations of this SNP with NAFLD are controversial and inconclusive [33,34,35,36]. This study aimed to elucidate the association of Pro12Ala with increased risk of NAFLD in Iranian patients with type 2 diabetes mellitus as a common metabolic disorder.

Material and methods

Subjects

This case–control study was based on 290 individuals of Iranian ancestry. The patient group included 145 patients with biopsy-proven NAFLD with a history of type 2 diabetes attending the Shahid Rajaei Cardiovascular Medical and Research Center in Tehran, Iran. All patients were recruited by use of liver biopsy. Only patients with a negative history of alcohol consumption and other known causes of chronic liver disease (e.g. autoimmune hepatitis, viral hepatitis, use of hepatotoxic medications such as antibiotics, glucocorticoids, tamoxifen or other anti-neoplastic drugs) were analyzed [5, 37]. Patients with unavailable liver ultrasound examination were excluded from the study. The controls were 145 individuals representing a general population sample from the same geographical region who had normal abdominal ultrasonography. Participants were matched for sex and age and numbers of men and women were equal in both groups. All participants gave written informed consent, and this study conforms to the principles of the Declaration of Helsinki. Both patient and control subjects’ characteristics including gender and age are shown in Table 1.

Table 1 Characteristics of study population

Clinical and laboratory findings were collected for each NAFLD patient from the clinical charts, including fasting blood sugar (FBS), BMI, creatine (Cr), total serum cholesterol (TC), triglyceride (TG), low-density lipoproteins (LDL) cholesterol, high-density lipoproteins (HDL) cholesterol, hemoglobin A1c (HbA1c), and microalbumin.

DNA extraction and molecular genotyping

Genomic DNA was isolated from peripheral blood leukocytes using Bioneer’s DNA extraction kit (Bioneer, Daejeon, Korea). Pro12Ala (CCG-GCG) alleles were determined by PCR–restriction fragment length polymorphism (RFLP) analysis using Bs1I restriction enzyme.

Forward and reverse primer sequences were 5′- TGTCTTGACTCATGGGTGTATTC-3′ and 5′- ATCAGTGAAGGAACCGCTTT-3′, respectively. Each PCR was performed in a final volume of 25 μl, including 100 ng of genomic DNA, 0.5 μl of each primer (10 pmol), 0.5 μl of dNTP, 0.8 μl of MgCl2, 2.5 μl of 10x PCR buffer and 2 units of Taq polymerase. The PCR conditions were as follows: initial denaturation at 95 °C for 5 min, then 35 cycles of 95 °C for 30 s, annealing at 57 °C for 30 s, extension at 72 °C for 30 s. This was followed by final extension at 72 °C for 5 min. The 185 bp amplified fragment was digested by restriction endonuclease Bs1I (Fermentas). The restriction fragments were separated by electrophoresis on a 2% agarose gel. Gel was stained with ethidium bromide and photographed by UV photography.

Statistical analysis

The data were analyzed using the SPSS 12.0 statistical software (SPSS, Chicago, IL, USA). Using the χ2 test, genotype and allele frequencies in the NAFLD and control subjects were compared. Student’s t test was applied to detect differences between groups with various genotypes regarding other variables such as age, FBS TG, TC, LDL, HDL and HbA1c. Odds ratios (OR) and their 95% confidence intervals (CI) were calculated. The associations between Pro12Ala polymorphism in the PPAR­γ2 gene with NAFLD and clinical and biochemical variables were evaluated. Data are presented as mean ± standard deviation (SD) and P values of less than 0.05 were considered significant for all tests.

Results

Digestion of PCR amplifications of the PPAR­γ2 gene with Bs1I gave different patterns, as shown in Fig. 1.

Fig. 1
figure 1

RFLP detection of Pro12Ala polymorphism of PPAR­γ2 gene using gel electrophoresis. M: Ladder 50 bp, lane 1: GG genotype (Pro12Ala) (185 bp), lanes 2, 3, and 4: CC genotype (Pro12Pro) (162, 23 bp)

The allelic and genotypic frequencies of the Pro12Ala PPAR­γ2 gene SNPs in patient and control subjects are shown in Table 2. As presented, there is no statistically significant difference regarding the allelic and genotypic frequencies of Pro12Ala PPAR­γ2 gene SNPs between the NAFLD patients and healthy control subjects (P = 0.64 and χ2 = 0.21).

Table 2 Genotypic association of the Pro12Ala polymorphism with NAFLD

The results showed no significant difference between the Pro12Ala carriers and wild-type individuals in the biochemical variables including BMI, FBS, Cr, lipid profile (TG, TC, HDL-C, and LDL-C), HbA1c, and micro albumin levels (data not shown).

Discussion

In this study, the association of PPAR­γ2 gene SNP Pro12Ala and increased risk of NAFLD was evaluated in patients with type 2 diabetes mellitus. Our results demonstrate that the polymorphism rs1801282 (c.34C > G, Pro12Ala) in the PPAR­γ2 gene is not associated with increased susceptibility to NAFLD in the Iranian population. Therefore, SNP Pro12Ala cannot be a genetic marker of NAFLD in this population.

NAFLD is independently associated with T2DM, obesity and metabolic syndrome, and the accumulation of fatty acid in the liver impairs insulin sensitivity. It has been hypothesized that the genetic variations (SNPs) found in metabolic syndrome patients may be related to NAFLD [38,39,40,41]. PPARγ is involved in regulation of adipogenic differentiation, lipid metabolism, insulin sensitivity and hepatic steatosis [42]. Thus, PPARγ is a promising candidate gene for several metabolic syndromes including T2DM, obesity, and NAFLD. However, the effect of PPARγ gene SNPs on the pathogenesis of NAFLD has not been clearly documented. Therefore, investigating the relationship between Pro12Ala PPAR­γ2 gene SNPs and increased susceptibility to NAFLD is important.

According to our results, the Pro12Ala SNP does not induce NAFLD in the Iranian population. Since the PPAR­γ gene contains several polymorphisms, other genetic variations may affect expression of the related molecule and be associated with NAFLD, which needs to be evaluated by further investigations.

However, the associations of Pro12Ala polymorphism with NAFLD have been reported to be varied in different populations and ethnic groups. For example, Gupta et al. investigated the Pro12Ala variant in 98 NAFLD patients and 280 matched controls and found that the Pro12Ala polymorphism was significantly associated with NAFLD in an Indian population [16]. Gawrieh et al., by evaluation of an American population, demonstrated that the SNP was associated with histologically advanced NAFLD [43]. Yang et al. revealed that Pro/Pro genotype of Pro12Ala was an increased risk factor for the development of NAFLD in Chinese patients [44]. A meta-analysis also demonstrated that the Pro12Ala variation of PPAR­γ2 was associated with susceptibility to NAFLD in East Asians, but not in European populations [13]. Bhatt et al. in a study with 162 Asian NAFLD patients and 173 controls observed that Pro12Ala SNP not only was associated with NAFLD but also was associated with alkaline phosphatase, higher serum TG, and waist-hip ratio [45].

Although the mentioned investigations revealed that PPARγ gene polymorphism was significantly associated with NAFLD in some population, Dongiovanni et al. observed that the PPAR-γ2 Pro12Ala frequency was not significantly different between NAFLD patients and healthy controls, in a study enrolling 202 Italian patients and 346 matched controls [12]. Rey et al. also reported that the incidence of the Ala12 mutant in German patients with NAFLD was not significantly different from healthy controls, and no significant difference was observed in histological inflammation in NAFLD [46]. Cao et al. studied the effect of Pro12Ala PPAR­γ2 gene SNPs in Chinese patients with NAFLD, including 169 NAFLD patients and 699 healthy subjects. Their analysis showed that the allele frequency was not significantly different between the two groups (p > 0.05) [4]. Domenici et al. found that Pro12Ala polymorphism was not associated with clinical, laboratory and histological parameters in NAFLD patients [8]. In the study by Chen et al., no association was found between PPAR-γ2 Pro12Ala substitution and NAFLD, and no significant difference was observed between this polymorphism and physiological variables [2]. Results from the meta-analysis of Sahebkar et al. indicated that Pro12Ala variation of PPAR­γ2 was not associated with NAFLD risk [47].

Generally, it seems that there is a significant controversy regarding the roles of PPARγ gene polymorphism in NAFLD pathogenesis. These consistencies could be the result of the different ethnic structure, referral and ascertainment biases, inadequate sample size, lack of mediators’ adjustment, or publication bias.

A possible limitation of our study was the small sample size, so further larger studies are required for confirmation.

In conclusion, the results of this study showed that Pro12Ala polymorphism of the PPAR­γ2 gene is not associated with increased susceptibility to NAFLD in the Iranian population. However, more studies with a larger sample size are needed to confirm this.

Abbreviations

NAFLD:

Non-alcoholic fatty liver disease

PPARs:

Peroxisome proliferator-activated receptors

RFLP:

Restriction fragment length polymorphism

T2DM:

Type 2 diabetes mellitus

References

  1. Wood KL, Miller MH, Dillon JF. Systematic review of genetic association studies involving histologically confirmed non-alcoholic fatty liver disease. BMJ Open Gastroenterol. 2015;2(1):e000019.

    Article  PubMed  PubMed Central  Google Scholar 

  2. Chen S-H, Ying L, Wu C, Wang Q, Li Y-M. Pro12Ala substitution in the peroxisome proliferator-activated receptor gamma (PPARγ) gene and non-alcoholic fatty liver disease. Arch Biol Sci. 2013;65(3):809–14.

    Article  Google Scholar 

  3. Dongiovanni P, Valenti L. Peroxisome proliferator-activated receptor genetic polymorphisms and nonalcoholic fatty liver disease: any role in disease susceptibility?. PPAR Res. 2013;2013:452061.

  4. Cao C-Y, Li Y-Y, Zhou Y-J, Nie Y-Q, Y-JY W. The C-681G polymorphism of the PPAR-γ gene is associated with susceptibility to non-alcoholic fatty liver disease. Tohoku J Exp Med. 2012;227(4):253–62.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  5. Saremi L, Lotfipanah S, Mohammadi M, Hosseinzadeh H, Sayad A, Saltanatpour Z. Association of HFE gene mutations with nonalcoholic fatty liver disease in the Iranian population. Cell Mol Biol (Noisy-le-grand). 2016;62(12):123.

    CAS  Google Scholar 

  6. Stefan N, Haring HU. The metabolically benign and malignant fatty liver. Diabetes2011. 2011:60.

  7. LaBrecque DR, Abbas Z, Anania F, Ferenci P, Khan AG, Goh K-L, et al. World gastroenterology organisation global guidelines: nonalcoholic fatty liver disease and nonalcoholic steatohepatitis. J Clin Gastroenterol. 2014;48(6):467–73.

    Article  PubMed  Google Scholar 

  8. Domenici FA, Brochado MJF, Martinelli AdLC, Zucoloto S, da Cunha SFdC, Vannucchi H. Peroxisome proliferator-activated receptors alpha and gamma2 polymorphisms in nonalcoholic fatty liver disease: a study in Brazilian patients. Gene 2013;529(2):326–331.

  9. Skrypnik D, Ratajczak M, Karolkiewicz J, Madry E, Pupek-Musialik D, Hansdorfer-Korzon R, Walkowiak J, Jakubowski H, Bogda-nski P. Effects of endurance and endurance–strength exercise on biochemical parameters of liver function in women with abdominal obesity. Biomed Pharmacother. 2016;80:1–7.

    Article  CAS  PubMed  Google Scholar 

  10. Skrypnik K, Suliburska J, Skrypnik D, Pilarski L, Reguła J, Bogdański P. The genetic basis of obesity complications. Acta Sci Pol Technol Aliment. 2017;16(1):83–91.

    CAS  PubMed  Google Scholar 

  11. Tolman KG, Dalpiaz AS. Treatment of non-alcoholic fatty liver disease. Ther Clin Risk Manag. 2007;3(6):1153.

    CAS  PubMed  PubMed Central  Google Scholar 

  12. Dongiovanni P, Rametta R, Fracanzani AL, Benedan L, Borroni V, Maggioni P, et al. Lack of association between peroxisome proliferator-activated receptors alpha and gamma2 polymorphisms and progressive liver damage in patients with non-alcoholic fatty liver disease: a case control study. BMC Gastroenterol. 2010;10(1):102.

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  13. Lee YH, Bae S-C, Song GG. Meta-analysis of associations between the peroxisome proliferator-activated receptor-γ Pro12Ala polymorphism and susceptibility to nonalcoholic fatty liver disease, rheumatoid arthritis, and psoriatic arthritis. Genet Test Mol Biomarkers. 2014;18(5):341–8.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  14. Schwimmer JB, Celedon MA, Lavine JE, Salem R, Campbell N, Schork NJ, et al. Heritability of nonalcoholic fatty liver disease. Gastroenterology. 2009;136(5):1585–92.

    Article  PubMed  Google Scholar 

  15. Guerrero R, Vega GL, Grundy SM, Browning JD. Ethnic differences in hepatic steatosis: an insulin resistance paradox? Hepatology. 2009;49(3):791–801.

    Article  PubMed  Google Scholar 

  16. Gupta A, Chaudhory A, Pande C, Sakhuja P, Singh Y, Basir S, et al. Peroxisome proliferators-activated receptor γ2 Pro12Ala variant is associated with body mass index in non-alcoholic fatty liver disease patients. Hepatol Int. 2011;5(1):575–80.

    Article  Google Scholar 

  17. Semple RK, Chatterjee VKK, O’Rahilly S. PPARγ and human metabolic disease. J Clin Invest. 2006;116(3):581–9.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  18. Kallwitz ER, McLachlan A, Cotler SJ. Role of peroxisome proliferators-activated receptors in the pathogenesis and treatment of nonalcoholic fatty liver disease. World J Gastroenterol. 2008;14(1):22.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  19. Beaven SW, Tontonoz P. Nuclear receptors in lipid metabolism: targeting the heart of dyslipidemia. Annu Rev Med. 2006;57:313–29.

    Article  CAS  PubMed  Google Scholar 

  20. Motavallian A, Andalib S, Vaseghi G, Mirmohammad-Sadeghi H, Amini M. Association between PRO12ALA polymorphism of the PPAR-γ2 gene and type 2 diabetes mellitus in Iranian patients. Indian J Hum Genet. 2013;19(2):239.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  21. Tavares V, Hirata R, Rodrigues A, Monte O, Salles J, Scallissi N, et al. Effect of the peroxisome proliferator-activated receptor-gamma C161T polymorphism on lipid profile in Brazilian patients with type 2 diabetes mellitus. J Endocrinol Investig. 2005;28(2):129–36.

    Article  CAS  Google Scholar 

  22. Bhatt SP, Misra A, Sharma M, Luthra K, Guleria R, Pandey RM, et al. Ala/ala genotype of Pro12Ala polymorphism in the peroxisome proliferator-activated receptor-γ2 gene is associated with obesity and insulin resistance in Asian Indians. Diabetes Technol Ther. 2012;14(9):828–34.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  23. Priya SS, Sankaran R, Ramalingam S, Sairam T, Somasundaram L. Genotype phenotype correlation of genetic polymorphism of PPAR gamma gene and Therapeutic response to pioglitazone in type 2 diabetes mellitus-a pilot study. J Clin Diagn Res. 2016;10(2):FC11.

    CAS  PubMed  PubMed Central  Google Scholar 

  24. Auwerx J. PPARγ, the ultimate thrifty gene. Diabetologia. 1999;42(9):1033–49.

    Article  CAS  PubMed  Google Scholar 

  25. Stumvoll M, Häring H. The peroxisome proliferator-activated receptor-γ2 Pro12Ala polymorphism. Diabetes. 2002;51(8):2341–7.

    Article  CAS  PubMed  Google Scholar 

  26. Saremi L, Saremi M, Lotfipanah S, Imani S, Zhang T, Fu J. Relation between PPARGC1A gene polymorphisms with the increased risk of coronary artery disease among patients with type 2 diabetes mellitus in Iran. Gen Endocrinol. 2015;11(1):13–7.

    Google Scholar 

  27. Saremi L, Saremi M, Lotfipanah S, Imani S, Fu J, Zhang T. Correlation between HFE gene polymorphisms and increased risk of coronary artery disease among patients with type 2 diabetes in Iran. Turk J Med Sci. 2016 Apr 19;46(3):590–6.

    Article  CAS  PubMed  Google Scholar 

  28. Caramori ML, Canani LH, Costa LA, Gross JL. The human peroxisome proliferator-activated receptor γ2 (PPARγ2) Pro12Ala polymorphism is associated with decreased risk of diabetic nephropathy in patients with type 2 diabetes. Diabetes. 2003;52(12):3010–3.

    Article  CAS  PubMed  Google Scholar 

  29. Tönjes A, Scholz M, Loeffler M, Stumvoll M. Association of Pro12Ala polymorphism in peroxisome proliferator–activated receptor γ with pre-diabetic phenotypes. Diabetes Care. 2006;29(11):2489–97.

    Article  PubMed  CAS  Google Scholar 

  30. Hegele RA, Cao H, Harris SB, Zinman B, Hanley AJ, Anderson CM. Peroxisome proliferator-activated receptor-γ2 P12A and type 2 diabetes in Canadian Oji-Cree 1. J Clin Endocrinol Metab. 2000;85(5):2014–9.

    CAS  PubMed  Google Scholar 

  31. Deeb SS, Fajas L, Nemoto M, Pihlajamäki J, Mykkänen L, Kuusisto J, et al. A Pro12Ala substitution in PPARγ2 associated with decreased receptor activity, lower body mass index and improved insulin sensitivity. Nat Genet. 1998;20(3):284–7.

    Article  CAS  PubMed  Google Scholar 

  32. Mohammadi-Asl J, Soheil-Nezhad A, Saremi L, Rahim F. Association of PPARG gene polymorphism (Pro12Ala) with type 2 diabetes in the Iranian population. HealthMed. 2013;7(4):1329–33.

    Google Scholar 

  33. Butt C, Gladman D, Rahman P. PPAR-gamma gene polymorphisms and psoriatic arthritis. J Rheumatol. 2006;33(8):1631–3.

    CAS  PubMed  Google Scholar 

  34. El-Sohemy A, Cornelis MC, Park Y-W, Bae S-C. Catalase and PPARγ2 genotype and risk of rheumatoid arthritis in Koreans. Rheumatol Int. 2006;26(5):388–92.

    Article  CAS  PubMed  Google Scholar 

  35. Terauchi Y. PPARgamma and metabolic syndrome. Rinsho byori Jpn J Clin Pathol. 2007;55(5):447–51.

    CAS  Google Scholar 

  36. Pan X, Song X, Wang L, Li L, Ying B. Association of the Pro12Ala polymorphism in peroxisome proliferators activated receptor-gamma gene with rheumatoid arthritis in Sichuan Province of China. Zhonghua yi xue yi chuan xue za zhi= Zhonghua yixue yichuanxue zazhi= Chin J Med Genet. 2009;26(1):87–90.

    CAS  Google Scholar 

  37. Saremi I, Saremi M, Lotfipanah S, Imani S, Zhang T, Fu J. Relationship between ppaRGC1a gene polymoRphisms with the inCReased risk of CoRonaRy aRteRy disease amonG patients with type 2 diabetes mellitus in iRan. Acta Endocrinologica-Bucharest. 2015;11(1):13–7.

    Article  Google Scholar 

  38. Willner IR, Waters B, Patil SR, Reuben A, Morelli J, Riely CA. Ninety patients with nonalcoholic steatohepatitis: insulin resistance, familial tendency, and severity of disease. Am J Gastroenterol. 2001;96(10):2957–61.

    Article  CAS  PubMed  Google Scholar 

  39. de Alwis NMW, Day CP. Genetics of alcoholic liver disease and nonalcoholic fatty liver disease. Semin Liver Dis; 2007: Copyright© 2007 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA.; 2007. p. 044–54.

  40. Méndez-Sánchez N, Arrese M, Zamora-Valdés D, Uribe M. Current concepts in the pathogenesis of nonalcoholic fatty liver disease. Liver Int. 2007;27(4):423–33.

    Article  PubMed  CAS  Google Scholar 

  41. Skrypnik K, Bogdański P, Łoniewski I, Reguła J, Suliburska J. Effect of probiotic supplementation on liver function and lipid statuse in rats. Acta Sci Pol Technol Aliment. 2018;17(2):185–92.

    CAS  PubMed  Google Scholar 

  42. Lee YH, Rho YH, Choi SJ, Ji JD, Song GG. Association of TNF-alpha–308 G/a polymorphism with responsiveness to TNF-α-blockers in rheumatoid arthritis: a meta-analysis. Rheumatol Int. 2006;27(2):157–61.

    Article  CAS  PubMed  Google Scholar 

  43. Gawrieh S, Marion MC, Komorowski R, Wallace J, Charlton M, Kissebah A, et al. Genetic variation in the peroxisome proliferator activated receptor-gamma gene is associated with histologically advanced NAFLD. Dig Dis Sci. 2012;57(4):952–7.

    Article  CAS  PubMed  Google Scholar 

  44. Yang Z, Wen J, Li Q, Tao X, Ye Z, He M, et al. PPARG gene Pro12Ala variant contributes to the development of non-alcoholic fatty liver in middle-aged and older Chinese population. Mol Cell Endocrinol. 2012;348(1):255–9.

    Article  PubMed  CAS  Google Scholar 

  45. Bhatt SP, Nigam P, Misra A, Guleria R, Luthra K, Pandey RM, et al. Association of peroxisome proliferator activated receptor-γ gene with non-alcoholic fatty liver disease in Asian Indians residing in North India. Gene. 2013;512(1):143–7.

    Article  CAS  PubMed  Google Scholar 

  46. Rey JW, Noetel A, Hardt A, Canbay A, Alakus H, Zur Hausen A, et al. Pro12Ala polymorphism of the peroxisome proliferator-activated receptor gamma2 in patients with fatty liver diseases. World J Gastroenterol. 2010;16(46):5830–7.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  47. Sahebkar A. Does PPARγ2 gene Pro12Ala polymorphism affect nonalcoholic fatty liver disease risk? Evidence from a meta-analysis. DNA Cell Biol. 2013;32(4):188–98.

    Article  CAS  PubMed  Google Scholar 

Download references

Acknowledgments

We thank all participants for contributing to our study. Special thanks to the staff of the referral centers of Shahid Rajaei Cardiovascular Medical and Research Center in Tehran, Iran.

Funding

This work was supported by the Tehran University of Medical Sciences, Tehran, Iran.

Availability of data and materials

The dataset supporting the conclusions of this article is included within the article. Also, the DNA samples of studied subjects and molecular materials are available for sharing.

Author information

Authors and Affiliations

Authors

Contributions

LS and ZS were in charge of samples collection, experimental design and PCR. SL and MM contributed equally performed and designed experiments, analyzed data, and generated Figs. BJ and HH were in charge of idea and concept of the paper and also performed studies on healthy controls and subjects’ collected and paper writing. ZS and MF were assisted in supervision and generated figures and edited the manuscript. All authors read and approved the final manuscript.

Corresponding author

Correspondence to Zohreh Saltanatpour.

Ethics declarations

Ethics approval and consent to participate

Institutional Ethics committees of Islamic Azad University and Southwest Medical University approved the study. This study was conducted in accordance with the Declaration of Helsinki (1964). Informed consent was obtained from all study participants. All study participants registered in the analysis were recruited from Shahid Rajaei Cardiovascular Medical and Research Center in Tehran, Iran. The informed consent explains to patients that they have a right to leave the study at any time.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Saremi, L., Lotfipanah, S., Mohammadi, M. et al. The Pro12Ala polymorphism in the PPAR­γ2 gene is not associated with an increased risk of NAFLD in Iranian patients with type 2 diabetes mellitus. Cell Mol Biol Lett 24, 12 (2019). https://doi.org/10.1186/s11658-019-0138-0

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1186/s11658-019-0138-0

Keywords