Association of Apo E gene polymorphism with HDL level in Tehranian population

Quantitative NMR-Based Lipoprotein Analysis Identifies Elevated HDL-4 and Triglycerides in the Serum of Alzheimer’s Disease Patients

Alzheimer’s disease (AD) is the most common form of dementia in the elderly and has been associated with changes in lipoprotein metabolism. We performed quantitative lipoprotein analysis in a local cohort of cognitively impaired elderly and control subjects using standardized nuclear magnetic resonance (NMR) spectroscopy. A commercially available quantitative NMR-based assay covering 112 lipoprotein main and subtype variables was used to investigate blood serum samples from a moderate cohort size of 161 persons (71 female, 90 male), including measures of quality control. Additionally, clinical metadata and cerebrospinal fluid AD biomarkers were collected and used for analysis. High-density lipoprotein (HDL) HDL-4 subfraction levels were mostly high in female individuals with mild cognitive impairment (MCI), followed by AD. Low-density lipoprotein (LDL) LDL-2 cholesterol was slightly elevated in male AD patients. HDL-2 apolipoprotein Apo-A1, HDL-2 phospholipids, and HDL-3 triglycerides were highly abundant in AD and MCI women compared to men. When considering clinical biomarkers (Aβ, tau), very low-density lipoprotein (VLDL) VLDL-1 and intermediate-density lipoprotein (IDL) triglycerides were substantially higher in AD compared to MCI. In addition, triglyceride levels correlated positively with dementia. Different lipoprotein serum patterns were identified for AD, MCI, and control subjects. Interestingly, HDL-4 and LDL-2 cholesterol parameters revealed strong gender-specific changes in the context of AD-driven dementia. As gender-based comparisons were based on smaller sub-groups with a low n-number, several statistical findings did not meet the significance threshold for multiple comparisons testing. Still, our finding suggests that serum HDL-4 parameters and various triglycerides correlate positively with AD pathology which could be a read-out of extended lipids traveling through the blood-brain barrier, supporting amyloid plaque formation processes. Thereof, we see herein a proof of concept that this quantitative NMR-based lipoprotein assay can generate important and highly interesting data for refined AD diagnosis and patient stratification, especially when larger cohorts are available.

Association of Apolipoprotein E gene polymorphism with the risk of T2DM and obesity among Egyptian subjects

BACKGROUND

Numerous reports investigated the involvement of apolipoprotein E (APOE) polymorphisms with elevated risk of type 2 diabetes mellitus (T2DM) and obesity. The principal objective of this study is to assess the contribution of APOE polymorphisms (rs429358 and rs7412) with the risk of T2DM and obesity.

SUBJECTS AND METHODS

This work was designed involving 400 participants [100 healthy controls, 100 T2DM patients, 100 obese patients, and 100 T2DM + obese patients]. Genomic deoxyribonucleic acid (DNA) of the APOE polymorphisms was characterized using the PCR-RFLP assay.

RESULTS

The common predominant genotype of the study population is the APOE Ɛ3/Ɛ3 [T2DM patients (46%), obese patients (52%), T2DM + obese patients (37%), and healthy controls (58%)]. The frequencies of the APOE Ɛ4/Ɛ4 genotype and the APOE*Ɛ4 allele were significantly elevated among T2DM patients (p-value < 0.05). Additionally, the frequencies of the APOE Ɛ2/Ɛ2 genotype and the APOE*Ɛ2 allele were significantly increased among obese patients (p-value < 0.05). Moreover, the frequencies of the APOE Ɛ2/Ɛ2 genotype, APOE*Ɛ2 allele, APOE Ɛ4/Ɛ4 genotype, and APOE*Ɛ4 allele were statistically significant among T2DM + obese patients (p-value < 0.05).

CONCLUSIONS

APOE*Ɛ2 and APOE*Ɛ4 alleles were considered as independent risk factor among T2DM + obese patients. Furthermore, the APOE*Ɛ2 allele was correlated with elevated risk of obesity, while the APOE*Ɛ4 allele was correlated with elevated risk of T2DM.

Genetic Identification for Non-Communicable Disease: Findings from 20 Years of the Tehran Lipid and Glucose Study

CONTEXT

Tehran Lipid and Glucose Study (TLGS), a longitudinal family based cohort study, is the oldest and largest longitudinal family based study in Iran, aimed at investigating effects of environmental, social and biological factors on the health of Tehranians over time. Considering the importance of genetic studies in this aspect, here we present a summary of the important genetic findings, and the potentiality of their contributions to future related projects.

EVIDENCE ACQUISITION

For all related studies during the past 20 years the search sources were all prominent search engines such as PubMed, Scopus, and Google Scholar with the most proper Medical Subject Headings (MeSH).

RESULTS

This review summarizes associations of 6 binary phenotypes and 17 quantitative traits with genetic markers in 26 genes. Of the 47 genetic markers, studied most were related to cardio metabolic risk factors. Results of heritability and linkage analysis were also collected and the highest heritability was found to be related to HDL-C (0.5).

CONCLUSION

Considering the opportunity provided by large-scale cohort studies to investigate molecular effects of genetic variants on causality and different omics' data, genetic studies conducted on TLGS population have had a remarkable success in identifying genetic variants that facilitating a unique genetic database on Iranian populations. The results of genome wide association studies in this population are currently facilitating investigations to define the Iranian genetic differences with other population.

The age effect on the association between the scavenger receptor class B type I (SR-BI) polymorphism and HDL-C level: Tehran Lipid and Glucose Study

INTRODUCTION

The scavenger receptor class B type I (SR-BI) is a key component in the reverse cholesterol transportation. The aim of this study was to assess the association between exon1 (G → A) polymorphism of SR-BI gene and lipid profiles among the Tehran Lipid and Glucose Study (TLGS) population.

MATERIALS AND METHODS

This cross-sectional study included 774 adults (322 males and 452 females) aged 20-70 years who were randomly selected from among TLGS population. Anthropometrical and biochemical variables for participants were measured. Selected SR-BI gene polymorphism was determined with restriction fragment length polymorphism, via Alu restriction enzyme.

RESULTS

Minor allele frequency for SR-BI polymorphism in the selected population was 0.159. Allele frequencies were in conformity with Hardy-Weinberg equilibrium. Association between (G → A) SR-BI polymorphism and high density lipoprotein cholesterol (HDL-C) and HDL3 was significant only after adjustment for age as a potential covariate (p = 0.046, 0.041, respectively); however, the results did not improve after adjustment for sex.

DISCUSSION

The result of this study confirms the role of age as a potential confounder which could modify the association between the SR-BI single nucleotide polymorphism and HDL-C level.

Haplotype analysis of Apo AI-CIII-AIV gene cluster and lipids level: Tehran Lipid and Glucose Study

Iranian populations show an increased tendency for abnormal lipid levels and high risk of Coronary artery disease. Considering the important role played by the ApoAI-CIII-AIV gene cluster in the regulation of the level and metabolism of lipids, this study aimed at elucidating the association between five single nucleotide polymorphisms on the Apo11q cluster gene and lipid levels. A cross-sectional study of 823 subjects (340 males and 483 females) from the Tehran lipid and glucose study (TLGS) was conducted. Levels of TG, Chol, HDL-C, Apo AI, Apo AIV, Apo B, and Apo CIII were measured, and the selected segments of the APOAI-CIII-AIV gene cluster were amplified by PCR and the polymorphisms were revealed by RFLP using restriction enzymes. The allele frequencies for each SNP between males and females were not significantly different. The distribution of Genotypes and alleles was in Hardy-Weinberg equilibrium except for Apo AI (+83C>T). The results showed a significant association between TG, HDL-C, HDL(2), Apo AI, and Apo B levels and the presence of some alleles in the polymorphisms studied. After haplotype analysis not only did the association between these variables and SNPs remain but also levels of Chol and LDL-C were added. This study demonstrates that the level of lipids such as TG, HDL-C, HDL(2), Apo AI, and Apo B, maybe regulated partly by genetic factors and their haplotype within the Apo11q gene cluster.

Association of CD36 gene variants and metabolic syndrome in Iranians

AIMS

The CD36 gene encodes for a membrane receptor that facilitates fatty-acid uptake and utilization. Genetic variants of the CD36 gene have been associated with metabolic syndrome (MetS). We aimed to evaluate the association between the rs10499859A>G and rs13246513C>T polymorphisms and MetS components.

METHODS

For this case-control study, 140 MetS and 187 normal subjects were randomly selected from the Tehran Lipid and Glucose Study participants. Biochemical and anthropometrical variables were measured. Genotyping for both single nucleotide polymorphisms (SNPs) was performed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

Case and control groups were not different in allele and genotype frequencies for these SNPs. However, the A and T alleles of these SNPs were significantly associated with elevated levels of high-density lipoprotein cholesterol (HDL-C) before age and sex adjustment (p=0.027 and 0.016, respectively). Association between the A allele and body mass index (BMI) was also significant after adjustment for MetS under the dominant model (p=0.009, β(2)=0.68).

CONCLUSIONS

Based on our results, these polymorphisms do affect HDL-C level and BMI (MetS components), although the effect may be slight and restricted specifically to an environment-genotype.