Association of PON1 and APOA5 gene polymorphisms in a cohort of Indian patients having coronary artery disease with and without type 2 diabetes.

Type 2 diabetes mellitus (T2DM) is a major cause of coronary artery disease (CAD) and is responsible for a great deal of morbidity and mortality in Asian Indians. Several gene polymorphisms have been associated with CAD and T2DM in different ethnic groups. This study will give an insight about the association of two selected candidate gene polymorphisms; paraoxonase1 (PON1) Q192R and apolipoprotein A5 (APOA5) -1131T>C were assessed in a cohort of South Indian patients having CAD with and without T2DM. Polymerase chain reaction-based genotyping of PON1 Q192R (rs662) and APOA5-1131T>C (rs662799) polymorphism was carried out in 520 individuals, including 250 CAD patients (160 with T2DM and 90 without T2DM), 150 T2DM patients with no identified CAD, and 120 normal healthy sex- and age-matched individuals as controls. The PON1 192RR genotype and R allele frequency were elevated in both CAD and T2DM patients when compared with controls; however, only CAD patients with T2DM showed a statistical significance (p=0.023; OR=1.49; 95% CI: 1.04-2.12) when compared with controls. The APOA5-1131CC genotype and C allele also showed a significant association between the CAD+T2DM patients when compared with CAD without T2DM and healthy controls (p=0.012; OR=1.71; 95% CI: 1.0-2.67). An additive interaction between the PON1 RR and APOA5 TC genotypes was identified between the T2DM and CAD patients (p=0.028 and 0.0382, respectively). PON1 and APOA5 polymorphisms may serve as biomarkers in the South Indian population to identify T2DM patients who are at risk of developing CAD.

The relationship of ACE and CETP gene polymorphisms with cardiovascular disease in a cohort of Asian Indian patients with and those without type 2 diabetes.

INTRODUCTION: Hypertension and dyslipidemia have been associated with cardiovascular disease (CVD). We investigated the association of candidate gene polymorphisms in angiotensin-converting enzyme (ACE) and cholesterol ester transfer protein (CETP) genes in a cohort of Asian Indian patients with and those without type 2 diabetes. METHODS: PCR-based genotyping of insertion/deletion (I/D) polymorphism of ACE (rs4646994) and -629C>A of CETP (rs1800775) was carried out in 520 individuals, of whom 160 had CVD+type 2 diabetes mellitus (T2DM), 90 were CVD patients without T2DM, 150 had T2DM with no cardiovascular complications, and 120 were age- and sex-matched healthy controls. RESULTS: With respect to the ACE gene I/D polymorphism, there was a higher percentage of D/D genotype in CVD+T2DM patients, but it was not statistically significant, while the CETP -629A allele was significantly associated with CVD+T2DM patients (P=.000007; odds ratio=0.46; 95% confidence interval=0.32-0.65) as compared with the normal controls and not with CVD alone. Additive interactions between the AA+I/I genotypes, AC+I/D genotypes, and AC+D/D were identified between the patients and the controls with P values of .0052, .0009, and .0078, respectively. CONCLUSIONS: Our study suggests that candidate gene polymorphism -629C>A of CETP may serve as a susceptibility biomarker for CVD in T2DM patients. Analyzing the combined effect of both ACE and CETP genotypes would enhance the sensitivity and specificity of CVD risk estimation in the T2DM patients in our population.

Association of methylene tetrahydrofolate reductase C677T genotype with type 2 diabetes mellitus patients with and without renal complications.

Diabetes is gradually getting the status of a global epidemic, with India projected as the capital of type 2 diabetes mellitus (T2DM). Nephropathy is an important complication of diabetes and a major cause of end-stage renal disease. Studies from different parts of the world have given controversial results regarding the association of methylene tetrahydrofolate reductase (MTHFR) gene variation with T2DM and diabetic nephropathy (DN). This case-control study assessed the association of MTHFR C677T mutation in T2DM and DN cases. Genotyping of MTHFR was carried out for 236 T2DM cases with diabetes diagnosed for >8 years, having either normoalbuminuria (n=100) or established DN (n=136). One hundred age- and sex-matched healthy individuals with normal blood sugars and no family history of T2DM were selected as controls. This first report from India gives a highly significant odds ratio of 4.0423 (95% confidence interval=1.8753-8.7133), indicating that the MTHFR 677T allele confers a fourfold risk of developing DM in our population. The frequency of the T allele in both the DM and DN groups was similar (i.e., 0.16 and 0.11, respectively), showing no association with the initiation or progression of DN. Individuals with a family history of diabetes or with risk factors such as obesity, hypertension, and impaired glucose tolerance should be screened for MTHFR C677T mutation and may be prescribed folic acid, vitamin B6, and vitamin B12 to assess if this helps in delaying the onset of diabetes.

Regulation of IGF2 transcript and protein expression by altered methylation in breast cancer.

PURPOSE: Breast Cancer is one of the leading causes of cancer deaths among women worldwide. The role of epigenetics as a distinct mechanism to alter gene expression in a tissue-specific manner has emerged as an important mechanism in the pathophysiology of cancer. Present study was carried out to assess the role of methylation in regulating transcription and protein expression of Insulin-like growth factor 2 (IGF2), an oncogene with parental imprinting. METHODS: Paraffin-embedded archival breast tumor and adjacent normal tissue samples were used for carrying out PCR-based methylation assay, genomic PCR, immunohistochemistry and Real-Time Reverse transcriptase PCR. RESULTS: A significant loss of methylation in exon 9 CpG cluster of IGF2 in breast tumor tissues was observed when compared to normal tissue (P < 0.0001). Expression of IGF2 by immunohistochemistry exhibited a mean twofold increase correlating with the hypomethylation of this specific CpG. Real-Time RT PCR showed increased transcripts in the tumor tissue supporting the IHC and methylation results. A total of 33% of tumor samples heterozygous for the ApaI IGF2 polymorphism exhibited biallelic IGF2 expression due to loss of imprinting; this was not seen in any of the normal breast tissues. CONCLUSIONS: Altered methylation of exonic CpG plays an important role in the enhanced transcription/expression of IGF2 in breast tumors. Methylation analysis of exon 9 CpG can be used as a biomarker for upregulation of IGF2 in breast tumor tissue and maybe developed as a diagnostic test in future.

Assessment of genetic damage in inflammatory, precancerous, and cancerous pathologies of the esophagus using the comet assay.

The last few decades of cancer research indicate that DNA damage is a prerequisite for development of malignancies. An increase in damage points to reduced repair capacity and risk for progression. We have used the comet assay to assess DNA damage in individuals with various disorders of the upper gastrointestinal (GI) tract in a cohort of patients from South India. After thorough clinical, endoscopic, and histopathological evaluation, patients were categorized into cancers, precancers, inflammatory pathologies, and controls. Results from the comet assay performed on esophageal tissue cells and blood from the same patients showed good correlation of damage in the paired samples; subsequent assays were performed in blood. There was more DNA damage in cancers when compared with controls. A significant increase in damage in cancers (37%) and precancers (30.7%) when compared with the inflammatory pathologies (15.6%) and controls (10.03%) was noted. The interindividual variation observed was independent of confounding factors such as tobacco and alcohol. We suggest that the damage seen in the esophageal tissue is likely to be disease-related, whereas that seen in blood may be a reflection of disease. Individuals with greater damage may be prone to disease progression and the comet assay can be used as a cost-effective biomonitoring tool to assess damage and identify these individuals at risk for a progressive pathology, even to malignancy.