Association Of PPAR-γ2, ApM-1 And PGC-1 With Type 2 Diabetes Mellitus In Korean And Han Chinese In Yanbian

OBJECTIVE Type 2 diabetes mellitus (T2DM) is a common polygenichereditary disease characterized as chronic hyperglycemia due to insulin resistance orsecretion decreases. It is also called complex disease. Hereditary factors play animportant role in the pathogenesis of T2DM. Both multiple minor genes andenvironment factors are responsible for the development of the disease. The purpose ofthis paper is to explore the risk factors and hereditary features of T2DM in Korean andHan ethnic nationality of Yanbian area in China, via the determination of the singlenucleotide polymorphisms (SNPs) of candidate genes of T2DM, the proxisomeproliferators activated receptor-γ, (PPAR-γ2), the adiopentin (αpM-1) and theperoxisome proliferator-activated receptor-γcoactivatorl (PGC-1), furthermore toanalyze their haplotypes and allele linkage disequilibrium.METHODS Part 1: A frequency matched case-control study was used base onthe epidemiological survey of T2DM in urban community population of Yanbian area inChina. 222 T2DM patients were taken randomly as case-group and 1747 as first-degreerelatives. Compared with case-group, 458 people having normal glucose tolerance wereselected as control-group and 2261 as first-degree relatives. The natural condition,living habit, patient history, symptoms, physical symptom, twenty items laboratoryexamination and genealogy atlas of all the persons tested were carried out. Falconer wasapplied to estimate heretability, and Li-Mantel-Gsrt to determine segregation ratio. Thehigh risk factors of T2DM were analyzed by unconditional univariate and multivariateLogistic regression. Part 2: The locations of genes of PPAR-γ2,αpM-1 and PGC-1were screened in Human SNPView of NCBI database and MapHap database using bioinformation methods. The 30 allele sites in this study were selected based on thehaplotype and haplotype tag SNP (htSNP) constructed in the database, as well asreported pappers. The genetic polymorphisms were determined by polymerase chainreaction-single strand conformational polymorphism (PCR-SSCP) and DNA sequencing.Case-contrast analysis was used to investigate the association between genepolymorphisms and gene frequencies in 269 T2DM patients (103 Korean and 156Chinese) and in 221 control subjects (108 Korean and 113 Chinese). The haplotype andlinkage disequilibrium of SNPs were analyzed using the SHEsis software on line(http://202.120.7.14/) in order to screen the risk factors of T2DM. Part 3: The SNPstransmission disequilibrium test (TDT) of 8 common sites of PPAR-γ2,αpM-1 andPGC-1 was conducted in the nuclear families of T2DM patients by using AssistantVersion 10.11 software (BioData, Ltd) in order to analyze the linkage between SNPsand T2DM.RESULTS Part 1: The prevalence rates of the T2DM first-degree relatives were5.09% and 4.82% respectively in Yanbian Korean and Han ethnic nationalities,significantly higher than those in control-group, which were 1.64% and 0.89% (P＜0.001). Prevalence relative risks (RR) were respectively raised 3.10 and 4.82 times.Among them, the first-degree relatives prevalence rate in Korean femalepatients(12.39%) was significantly higher than that in Korean male, Han ethnicnationality (4.67%, 4.85% and 4.80% respectively, P＜0.05). The first-degree relativesRR in Korean female patients were 2.6 times more than that in other relationships.Statistical results indicated the prevalence rate of T2DM was not significantly differentbetween Korean and Han ethnic nationality (P=0.809, 0.056). It illustrated nonationality difference in Yanbian, but having an evidently hereditary tendency. Totalprevalence rate of T2DM was 39.6% in Yanbian. Prevalence rate of Korean and Hanethnic nationalities were 39.4% and 51.6% respectively. Han ethnic nationality washigher than Korean nationality, but no significant difference. The first-degree relatives prevalence rate in Korean female (76.4%) was significantly higher than that in male(37.2%, P＜0.001). It pointed out that the first-degree relatives' prevalence rate ofT2DM in Korean female had a hereditary liability than other people. The segregationratio of T2DM in Korean and Han ethnic nationality in Yanbian were 0.21 and 0.15,which were lower than 0.25, and not meet the features of single gene inheritance disease,and support the character of polygenic diseases. Family history of T2DM, hypertension,waist-to-hip ratio (WHR), intaking of sweet food were the major risk factors of T2DM.Part 2:15 gene polymorphisms were found from PPAR-γ2,αpM-1 and PGC-1 byPCR-SSCP and DNA sequencing. They were Pro12Ala and C161T (His477His) inPPAR-γ2; -11391 G＞A, -11377C＞G, -11156 insCA, T45G (Glyl5Gly), +276C＞A,+349A＞G, R221S and H241P inαpM-1; Thr394Thr, IVS2+52C＞A, Gly482Ser(G＞A),Thr528Thr(G＞A), Ser577Leu (C＞T) in PGC-1. Whereas, 15 SNPs were not detected inthis study. They were Pro115Gln, Gln438Gln, Ser457Ser, Leu481Leu, IVS2+40C＞T,-11426G＞A, -11043C＞T, +162G＞A(Gly54Val), +1711C＞T, +1795 A＞G, +1833 C＞A,Ser74Leu, Leu 410 Iso, Leu 438 Ser and Ser577Leu. The rare genes were -11391G＞A(A frequency 0.009), Ler475SerC＞T (T frequency 0.0013), R221SC＞A (A frequency0.003), H241P A＞C (C frequency 0.0015). The results meet the Hardy-Weinberg law.The genotype frequency and allele frequency of Pro12Ala in PPAR-γ2 in Han T2DMand NGT groups were PP: 0.954 and 0.960; PA: 0.046 and 0.040; A frequency 0.023and 0.020. However, those in Korean T2DM and NGT groups were PP: 0.948 and 0.955;PA: 0.052 and 0.045; A frequency 0.026 and 0.022. No difference was found betweenT2DM and NGT groups. The genotype frequency and allele frequency of 5 SNPs inαpM-1 in T2DM and NGT groups were G in -11377C＞G: 0.237 and 0.225; I in-11156insCA: 0.132 and 0.158; G in T45G: 0.294 and 0.389; T in +276G＞T: 0.294 and0.289; G in +349A＞G: 0.324 and 0.389. There was no difference. We also failed to findthe difference in the genes IVS2+52C＞A, Thr394Thr, Gly482Ser(G＞A) and Thr528Thr(G＞A) in PGC-1 between Han and Korean. The combined genotypes CC-GA-PA, CA-GA-PP, CA-GG-PP, CC-GG-PP and CC-AA-PP in IVS2+52C＞A and Gly482Ser ofPGC-1 as well as in Prol2Ala of PPAR-γ2 appeared in high frequency (over 5%).Part 3: The 8 SNPs(-11377C＞G, -11156 insCA, Gly15Gly (T45G), +276C＞A,+349A＞G, IVS2+52 C＞A, Gly482Ser and Thr528Thr from PPAR-γ2, apM-1 andPGC-1 were not associated with T2DM in Han and Korean as showed in TDT.CONCLUSION (1) The major risk factors of T2DM in Yanbian area are family history,hypertension, WHR and intaking of sweet food. The hereditary character of T2DM ispolygenic. (2) 15 SNPs: Prol2Ala, C161T, -11391G＞A, -11377C＞G, -11156insCA, T45G(Gly15Gly), +276C＞A, +349A＞G, R221S, H241P, Thr394Thr, IVS2+52C＞A,Gly482Ser(G＞A), Thr528Thr(G＞A) and Ser577Leu(C＞T) in PPAR-γ2, apM-1 andPGC-1 related with T2DM were detected in Han and Korean in Yanbian of China. (3)There were no differences in genotype frequency and allele frequency of 15 SNPsabove between Han and Korean nationalities in Yanbian of China. (4) Thepolymorphisms of IVS2+52C＞A and Gly482Ser in PGC-1, C161T in PPAR-γ2 wereassociated with T2DM, possibly by interfering with lipid metabolism. (5) Thegenotypes C161T, -11377C＞G, -11156InsCA, T45G, +276C＞A, +349A＞G. IVS2+52C＞A and Gly482Ser(G＞A) in PPAR-γ2, apM-1 and PGC-1 were not associated withT2DM in Yanbian Han and Korean patients.