Association of VEGFA variants with altered VEGF secretion and type 2 diabetes: A case-control study.

BACKGROUND: Vascular endothelial growth factor (VEGF) contributes to type 2 diabetes (T2DM) pathogenesis, and genetic variations in VEGFA gene were suggested to influence VEGF secretion and T2DM pathogenesis. AIM: To evaluate the association of specific VEGFA variants with altered VEGF levels, and with T2DM among Tunisians. SUBJECTS AND METHODS: A retrospective case-control study, performed on 815 T2DM patients, and 805 healthy controls. VEGF levels were measured by ELISA, genotyping of VEGFA variants was done by allelic exclusion method (real-time PCR). RESULTS: MAF of rs1570360, rs2010963, rs25648, rs833068, rs3025036, and rs3025039 were significantly different between T2DM cases and controls. Increased T2DM risk was associated with rs699947, rs1570360, and rs3025020, while reduced T2DM risk was seen with rs1547651, rs2010963, rs25648, rs3025036, and rs3025039 genotypes, thus assigning T2DM susceptibility and protection, respectively. Reduced VEGF levels were associated with rs833061, rs2010963, and rs3025039 heterozygosity and rs3025036 major allele homozygosity in T2DM cases, while increased VEGF levels were seen in rs833070 homozygous major allele genotype. Both rs699947 and rs1570360 positively, while rs2010963 and rs3025036 negatively correlated with fasting glucose. In addition, rs699947 positively correlated with LDL-cholesterol, and rs3025039 positively correlated with diabetes duration, but negatively with HbA1c and serum triglycerides. Haploview analysis identified Block 1 containing 8 loci, and Block 2 with the remaining 3 loci. Haplotypes ACTGCCGG and AACGGCGA (Block 1) were negatively associated with T2DM, while haplotype CCC was positively and haplotype CGC (Block 2) were negatively associated with T2DM. CONCLUSION: This study confirms the contribution of altered VEGF secretion, resulting from genetic variation in VEGFA gene into T2DM pathogenesis, hence supporting role for VEGFA as T2DM candidate locus.

Differential association of ESR1 and ESR2 gene variants with the risk of breast cancer and associated features: A case-control study.

BACKGROUND: Estrogen is key to breast cancer pathogenesis, and acts by binding its receptor (ER), which exists as ERα and ERß, encoded by ESR1 and ESR2 genes, respectively. Studies that investigated the association of ESR1 and ESR2 variants with breast cancer yielded mixed outcome, and ethnic contribution was proposed. We evaluated the association between ESR1 and ESR2 variants and breast cancer and associated features in Tunisian women. METHODS: Retrospective case-control study involving 207 female breast cancer patients, and 284 control women. Genotyping was done by real-time PCR. RESULTS: Minor allele frequencies (MAF) of tagging SNPs rs2234693 and rs3798577 (ESR1) were significantly higher, while MAF of rs1256049 (ESR2) was significantly lower in breast cancer patients vs. CONTROLS: Patients carrying rs3798577 genotypes had higher risk, while rs1256049 genotype carriers had reduced risk of breast cancer. The association of ESR1 and ESR2 gene variants with breast cancer depended on ER and Her-2 status. ESR1 rs3798577 and ESR2 rs1256049 were associated with breast cancer in ER-positive cases, and ESR1 rs2234693, and rs3798577 were associated with breast cancer in Her-2-negative cases, while the association of ESR2 rs1256049 with breast cancer was seen in Her-2 positive cases. Haploview analysis identified 4-locus ESR1 haplotypes that were positively (CGTT, TACC, and TACT), and negatively (CGTC) associated with breast cancer. No ESR2 haplotypes associated with breast cancer were identified. CONCLUSION: ESR1 alleles and genotypes, and specific 3-locus ESR1 haplotypes are related with increased breast cancer susceptibility in Tunisian women. However, ESR2 variant and specific 1-locus ESR1 haplotype have a protective effect.

Differential association of DENND1A genetic variants with polycystic ovary syndrome in Tunisian but not Bahraini Arab women.

BACKGROUND AND AIM: Polycystic ovary syndrome (PCOS) is a common endocrine disorder, and results from interaction between modifiable and non-modifiable factors, including genetic predisposition. Previous genome-wide association studies and meta-analysis identified DENND1A as PCOS susceptibility locus in some, but not all populations. We investigated whether the association of DENND1A gene variants with PCOS was similar between Tunisian and Bahraini Arab women. SUBJECTS AND METHODS: This was retrospective case-control study. Study subjects comprised 320 women with PCOS, and 446 age-and ethnically-matched control women. Genotyping of DENND1A rs10818854, rs2479106, and rs10986105 variants was done by real-time PCR. RESULTS: Minor allele frequency of rs10818854 and rs10986105 DENND1A variants were significantly higher among women with PCOS. Setting homozygous wild-type genotype carrier as reference, rs10818854 and rs10986105 were associated with increased risk of PCOS, which persisted after controlling for key covariates, while reduced PCOS risk was seen with only rs2479106 under the additive model. This assigned PCOS susceptibility and protective nature to these genotypes, respectively. Both rs10818854 and rs10986105 were positively associated with HOMA-IR and AMH in women with PCOS. Haploview analysis revealed limited linkage disequilibrium between the tested DENND1A variants. Extensive diversity in haplotypes assignment was seen, with most haplotypes (99.5%) captured by 5 haplotypes. Taking GAT haplotype as reference, AAG, and GAG haplotypes were positively, while GAT haplotype was negatively associated with PCOS. CONCLUSION: The association of DENND1A rs10818854 and rs10986105 variants with PCOS in Tunisian but not Bahraini women confirms the dependence of this association on the ethnic/racial origin of study subjects.