[Show abstract][Hide abstract] ABSTRACT: Recent genome-wide association scans (GWAS) and replication studies have expanded the list of validated type 2 diabetes (T2DM) susceptibility loci. We replicated T2DM association of 19 SNPs from 15 candidate loci in Lebanese Arabs.
Case-control association study, comprising 995 T2DM patients and 1076 control participants. We genotyped by the allelic discrimination method 19 SNPs in/near ADAM30, NOTCH2, THADA, TMEFF2, COL8A1, ADAMTS9-AS2, WFS1, JAZF1, SLC30A8, KCNQ1, LOC387761, ALX4, TSPAN8, FTO, and HNF1.
Allele frequencies of the tested SNPs were comparable with those of Caucasians. COL8A1 rs792837 (P=2.9×10(-9)), KCNQ1 rs2237892 (P=1.8×10(-18)) and rs2237895 (P=0.002), ALX4 rs729287 (Pc=7.5×10(-5)), and HNF1 rs4430796 (P=0.003) were significantly associated with T2DM, with similar effect sizes to those of Europeans. While FTO rs8050136 and rs17817449, ADAMTS9 rs4607103, and WFS1 rs10010131 were initially associated with T2DM, this was lost upon multiple testing correction. The remaining variants were not associated with T2DM, possibly resulting from insufficient power to detect smaller allele effects.
In addition to previous findings on the association of IGF2BP2, CDKAL1, TCF7L2 variants with T2DM among Lebanese, here we extend these by validating the association of five additional loci with T2DM in Lebanese Arabs.
Full-text · Article · Sep 2013 · Diabetes research and clinical practice
[Show abstract][Hide abstract] ABSTRACT: Recent genome-wide association studies and replication analyses have reported the association of variants of the exostosin-2 (EXT2) gene and risk of type 2 diabetes mellitus (T2DM) in some populations, but not in others. This study investigated the associations of EXT2 variants rs1113132, rs3740878 and rs11037909 with T2DM in a Lebanese Arab population.
This case-control study involved 995 T2DM patients and 1076 control subjects. Genotyping was done by the allelic exclusion method.
While minor allele frequencies (MAFs) of rs11037909 (P=0.028) and rs3740878 (P=0.048), but not rs1113132 (P=0.841), were higher in patients, this was lost after correcting for multiple testing. Apart from EXT2 rs1113132, which was marginally associated with T2DM in the additive model (P=0.054), but not after adjustment for covariates, none of the tested EXT2 SNPs were associated with T2DM in any of the genetic models tested. However, variable associations of EXT2 variants with T2DM were noted according to BMI status. While the three tested EXT2 variants were not associated with T2DM in obese subjects, rs1113132 and rs11037909, but not rs3740878, were associated with T2DM in non-obese subjects. Meta-analysis revealed a significant association of rs11037909 and a marginal association of rs3740878 with T2DM in the fixed model. Using a common (GTA) haplotype as reference, three-locus (rs1113132/rs11037909/rs3740878) haplotype analysis demonstrated no association between any of the EXT2 haplotypes with T2DM, not even before correcting for multiple testing.
This study demonstrated no association of rs1113132, rs3740878 and rs11037909 EXT2 variants with T2DM.
[Show abstract][Hide abstract] ABSTRACT: We tested the association of TCF7L2 variants with type 2 diabetes (T2DM) in 691 Lebanese people and 919 controls. rs7901695, rs4506565, rs7903146, rs12243326, rs7895340, and rs12255372 minor allele frequencies were higher in T2DM. Haplotype analysis (rs7901695-rs4506565-rs7903146-rs12243326-rs7895340-rs11196205-rs12255372) identified positively- (2122112, 2222222) and negatively- (1111111) T2DM-associated haplotypes. TCF7L2 is a common T2DM candidate gene in Lebanese people.
No preview · Article · Oct 2012 · Diabetes research and clinical practice
[Show abstract][Hide abstract] ABSTRACT: Background:
While several type 2 diabetes mellitus (T2DM) susceptibility loci identified through genome-wide association studies (GWAS) have been replicated in many populations, their association in Arabs has not been reported. For this reason, the present study looked at the contribution of ENNP1 (rs1044498), IGF2BP2 (rs1470579), KCNJ11 (rs5219), MLXIPL (rs7800944), PPARγ (rs1801282), SLC30A8 (rs13266634) and TCF7L2 (rs7903146) SNPs to the risk of T2DM in Lebanese and Tunisian Arabs.
Study subjects (case/controls) were Lebanese (751/918) and Tunisians (1470/838). Genotyping was carried out by the allelic discrimination method.
In Lebanese and Tunisians, neither ENNP1 nor MLXIPL was associated with T2DM, whereas TCF7L2 was significantly associated with an increased risk of T2DM in both the Lebanese [P < 0.001; OR (95% CI): 1.38 (1.20-1.59)] and Tunisians [P < 0.001; OR (95% CI): 1.36 (1.18-1.56)]. Differential associations of IGF2BP2, KCNJ11, PPARγ and SLC30A8 with T2DM were noted in the two populations. IGF2BP2 [P = 1.3 × 10(-5); OR (95% CI): 1.66 (1.42-1.94)] and PPARγ [P = 0.005; OR (95% CI): 1.41 (1.10-1.80)] were associated with T2DM in the Lebanese, but not Tunisians, while KCNJ11 [P = 8.0 × 10(-4); OR (95% CI): 1.27 (1.09-1.47)] and SLC30A8 [P = 1.6 × 10(-5); OR (95% CI): 1.37 (1.15-1.62)] were associated with T2DM in the Tunisians, but not Lebanese, after adjusting for gender and body mass index.
T2DM susceptibility loci SNPs identified through GWAS showed differential associations with T2DM in two Arab populations, thus further confirming the ethnic contributions of these variants to T2DM susceptibility.
Full-text · Article · Jun 2012 · Diabetes & Metabolism
[Show abstract][Hide abstract] ABSTRACT: Several genome-wide association studies and replication analyses have identified common variation at the insulin-like binding protein 2 (IGF2BP2) gene to be associated with type 2 diabetes (T2DM). The aim of this study was to replicate in a Lebanese Arab population identified associations of IGF2BP2 variants rs4402960 and rs1470579 with T2DM.
This case-control study involved 544 T2DM patients and 606 control subjects. Genotyping was done by the allelic exclusion method.
T allele of rs440960 (P=6.5 × 10(-6)) and C allele of rs1470579 (P=5.3 × 10(-4)) were significantly associated with T2DM; both SNPs were in strong LD (D'=0.83, r(2)=0.58). While both IGF2BP2 SNPs were significantly associated with T2DM under additive and recessive models, only rs4402960 remained significantly associated with T2DM under the dominant model. Taking the common rs4402960/rs1470579 GA haplotype as reference, multivariate analysis confirmed the positive association of TC (P=0.009; OR, 1.43; 95%CI, 1.09-1.87), and TA (P<0.001; OR=5.49; 95%CI=2.09-14.39) haplotypes with increased T2DM risk. These differences remained significant after applying the Bonferroni correction for multiple testing.
We validate that IGF2BP2 susceptibility variants rs4402960 and rs1470579 associate with T2DM in Lebanese Arabs.
Full-text · Article · Jan 2012 · Diabetes research and clinical practice
[Show abstract][Hide abstract] ABSTRACT: Methylenetetrahydrofolate reductase (MTHFR) gene variants and hyperhomocysteinemia have been implicated in the pathogenesis of diabetic nephropathy (DN) in various ethnic groups. We investigated the association of C677T and A1298C MTHFR gene variants and altered homocysteine concentrations in Lebanese and Bahraini type 2 diabetes (T2DM) DN patients.
Bahraini subjects comprised 224 DN patients and 328 T2DM patients with normal urine albumin [diabetes without nephropathy (DWN)]. Lebanese subjects comprised 252 DN and 309 DWN patients. C677T and A1298C genotypes were determined by PCR-restriction fragment length polymorphism (RFLP) analysis, and homocysteine was measured by ELISA.
A1298C allele and genotype distribution were comparable between DN and DWN patients in both communities. However, there was enrichment of the 677T allele, together with C/T and T/T genotypes in Lebanese but not Bahraini DN patients, thereby conferring DN susceptibility [odds ratio (OR) (95% CI)=2.43 (1.89-3.11) and OR (95% CI)=1.15 (0.83-1.61), respectively; heterogeneity Q=12.53, p=0.0004)].
The contribution of C677T single nucleotide polymorphism to increased risk of DN (presumably by increasing homocysteine concentrations) must be evaluated in the context of the ethnic background.
No preview · Article · Aug 2010 · Clinical Chemistry and Laboratory Medicine
[Show abstract][Hide abstract] ABSTRACT: Factor V G1691A (FV-Leiden) and prothrombin (PRT) G20210A single nucleotide polymorphisms (SNPs) were associated with venous thrombosis among Caucasians. We assessed the contribution of both SNPs to the genetic susceptibility of deep venous thrombosis (DVT) among Lebanese and Tunisian patients. Subjects comprised 198 DVT patients and 540 healthy controls from Lebanon and 126 Tunisian DVT patients and 197 control subjects; FV-Leiden (MnlI) and PRT G20210A (HindIII) genotyping was done by PCR-RFLP. While the prevalence of FV-Leiden mutant A allele and the G/A and A/A genotypes were significantly higher among DVT patients from Lebanon and Tunisia, the association of PRT G20210A with DVT was pronounced among Lebanese but not Tunisian patients. The prevalence of PRT G20210A mutant A allele (P < 0.001 vs. P = 181) and G/A genotype (P < 0.001 vs. P = 0.994) was significantly higher among Lebanese but not Tunisians, respectively. While FV-Leiden was a common genetic risk factor for DVT in both communities, the contribution of PRT G20210A to the genetic susceptibility of DVT differed among Lebanese and Tunisians, which underscores the need to determine prothrombotic gene polymorphisms associated with DVT among Arab and Mediterranean basin communities.
Full-text · Article · Aug 2006 · American Journal of Hematology
[Show abstract][Hide abstract] ABSTRACT: Factor V G1691A (FV-Leiden) and prothrombin (PRT) G20210A single nucleotide polymorphisms (SNPs) are major inherited risk factors of venous thromboembolism. In view of the heterogeneity in their world distribution and lack of sufficient information about their distribution among Arabs, we addressed the prevalence of both SNPs in 4 distinct Arab populations (Lebanon, Tunisia, Bahrain, and Saudi Arabia).
Study subjects comprised 698 Lebanese, 313 Tunisian, 194 Bahraini, and 149 Saudi Arabian healthy subjects; genotyping was done by PCR-RFLP using Mnl I and Hind III for FV-Leiden and PRT G20210A, respectively.
The prevalence of the mutant A alleles of FV-Leiden and PRT G20210A were significantly higher among Lebanese (0.0788 and 0.0136) and Tunisians (0.0351 and 0.0128), as compared to Bahraini (0.0155 and 0.0052) and Saudi (0.0101 and 0.000) subjects. Higher frequency of the FV-Leiden G/A and A/A genotypes were seen in Lebanon (13.8 and 1.0%), followed by Tunisia (5.8 and 0.6%), Bahrain (3.1 and 0.0%) and Saudi Arabia ((2.0 and 0.0%). All PRT G20210A positive cases were in the heterozygote (G/A) state, and these comprised 3.6% for Lebanon, 2.6% for Tunisia, 1.0% for Bahrain. The carrier rate of FV-Leiden was significantly higher among Lebanese compared to the other populations (p < 0.001), while the difference in the prevalence of FV-Leiden between the other populations was not statistically different. With the exception of Lebanese-Saudi (p = 0.038), the prevalence of PRT G20210A was similar among the study communities. Furthermore, the overall average genetic differentiation between populations (estimated with the F(ST)) was 0.0022 for FV-Leiden and 0.005 for PRT G20210A.
These results further confirm the heterogeneity in FV-Leiden and PRT G20210A distribution among Arabs, and recommend potential institution of prophylactic measures for carriers of either or both SNPs.
Full-text · Article · Jan 2006 · Journal of Thrombosis and Thrombolysis
[Show abstract][Hide abstract] ABSTRACT: The association of the single nucleotide polymorphisms (SNPs) G1691A in coagulation factor V (FV)-Leiden and G20210A in prothrombin (PRT) genes with type 2 diabetes mellitus (T2DM) were analyzed in 112 T2DM patients (58 males, 54 females; mean age 55.24 +/- 13.5 years) and 249 healthy control subjects (118 males, 131 females; mean age 53.03 +/- 13.8 years). No association was found for FV-Leiden with T2DM, as the frequency of the G/G (82.1% vs. 85.5%), G/A (17.0% vs. 14.1%), and A/A (0.9% vs. 0.4%) genotypes was not different between patients and controls, respectively (P = 0.644). Similarly, lack of association of PRT G20210A with T2DM was seen among the population studied, and the frequency of the G/G (92.9% vs. 97.2%), G/A (6.3% vs. 2.8%), and A/A (0.9% vs. 0.0%) genotypes was similar among patients and controls, respectively (P = 0.094). Neither FV-Leiden nor PRT G20210A was associated with, and no evidence for interactions between these mutations was seen in, T2DM.
Full-text · Article · Sep 2005 · American Journal of Hematology