Presence of coronary artery disease in diabetic and non diabetic South Asian immigrants

Introduction South Asian Immigrants (SAIs) are the second fastest growing Asian immigrant population in the US, and at a higher risk of type 2 diabetes (diabetes) and coronary artery disease (CAD) than the general US population. Objectives: We sought to determine in SAIs the; 1) the prevalence of CAD risk factors in diabetics and non-diabetics; and b) the high possibility of CAD in diabetic SAIs. We also assessed the prevalence of sub-clinical CAD in both diabetics and non-diabetics SAIs using common carotid artery Intima-media thickness (CIMT) as a surrogate marker for atherosclerosis. Methods In a cross-sectional study design, 213 first generation SAIs were recruited and based on the history, and fasting glucose levels were divided into two subgroups; 35 diabetics and 178 non-diabetics. 12-hour fasting blood samples were collected for glucose and total cholesterol levels. Exercise Tolerance Test (ETT) was performed to determine the possibility of CAD. Results Both diabetics and non-diabetics SAIs in general, share a significant burden of CAD risk factors. The prevalence of hypertension (p = 0.003), total cholesterol ≥ 200 mg/dl (p < 0.0001) and family history of diabetes (p < 0.0001) was significantly was significantly higher in diabetics compared to non-diabetics. Of the 22/29 diabetic participants without known history of CAD, 45% had positive ETT (p < 0.001). Similarly, 63.1% of diabetics and 51.8 % of non-diabetics were positive for sub-clinical CAD using CIMT as a marker. Conclusion The susceptibility to diabetes amongst SAIs promotes an adverse CAD risk, as evident by this small study. Further research, including larger longitudinal prospective studies, is required to validate the current small study findings with investigation of the temporal association.

APOA1 gene polymorphisms in the South Asian immigrant population in the United States.

BACKGROUND: Coronary artery disease (CAD) is a leading cause of death in the United States. South Asian immigrants (SAIs) from the Indian subcontinent living in the US are disproportionately at higher risk of CAD than other immigrant populations. Unique genetic factors may predispose SAIs to increased risk of developing CAD when adopting a Western lifestyle including a higher-fat diet, more sedentary behavior and additional gene-environment interactions. SAIs are known to have low levels of the protective high density lipoprotein (HDL) and an altered function for Apo-lipoprotein A-1 (ApoA1), the main protein component of HDL cholesterol. One gene that may be genetically distinctive in this population is APOA1 which codes for ApoA-1 protein, a potentially important contributing factor in the development of CAD. MATERIALS AND METHODS: DNA sequencing was performed to determine the status of the seven single-nucleotide polymorphisms (SNPs) in the APOA1 gene from 94 unrelated SAI adults. Genotypes, allelic frequencies, and intragenic linkage disequilibrium of the APOA1 SNPs were calculated. RESULTS: Several polymorphisms and patterns were common among persons of south Asian ethnicity. Frequencies for SNPs T655C, T756C and T1001C were found to be different than those reported in European Caucasian individuals. Linkage disequilibrium was found to be present between most (13 of 15) SNP pairings indicating common inheritance patterns. CONCLUSIONS: SAIs showed variability in the sequence of the APOA1 gene and linkage disequilibrium for most SNPS. This pattern of APOA1 SNPs may contribute to decreased levels of HDL cholesterol reported in SAIs, leading to an increased risk for developing CAD in this population.

Can novel Apo A-I polymorphisms be responsible for low HDL in South Asian immigrants.

Coronary artery disease (CAD) is the leading cause of death in the world. Even though its rates have decreased worldwide over the past 30 years, event rates are still high in South Asians. South Asians are known to have low high-density lipoprotein (HDL) levels. The objective of this study was to identify Apolipoprotein A-I (Apo A-I) polymorphisms, the main protein component of HDL and explore its association with low HDL levels in South Asians. A pilot study on 30 South Asians was conducted and 12-h fasting samples for C-reactive protein, total cholesterol, HDL, low-density lipoprotein (LDL), triglycerides, Lipoprotein (a), Insulin, glucose levels, DNA extraction, and sequencing of Apo A-I gene were done. DNA sequencing revealed six novel Apo A-I single nucleotide polymorphisms (SNPs) in South Asians, one of which (rs 35293760, C938T) was significantly associated with low (<40 mg/dl) HDL levels (P = 0.004). The association was also seen with total cholesterol (P = 0.026) and LDL levels (P = 0.032). This pilot work has highlighted some of the gene-environment associations that could be responsible for low HDL and may be excess CAD in South Asians. Further larger studies are required to explore and uncover these associations that could be responsible for excess CAD risk in South Asians.