A functional polymorphism in the lymphotoxin-alpha gene is associated with carotid artery wall thickness: the Diabetes Heart Study

Review of the Diabetes Heart Study (DHS) family of studies: a comprehensively examined sample for genetic and epidemiological studies of type 2 diabetes and its complications

The Diabetes Heart Study (DHS) is a genetic and epidemiological study of 1,443 European American and African American participants from 564 families with multiple cases of type 2 diabetes. Initially, participants were comprehensively examined for measures of subclinical cardiovascular disease (CVD) including computed tomography measurement of vascular calcified plaque, ultrasound imaging of carotid artery wall thickness, and electrocardiographic intervals. Subsequent studies have investigated the relationship between bone mineral density and vascular calcification, measures of adiposity, and biomarkers. Ongoing studies are carrying out an extensive evaluation of cerebrovascular disease using magnetic resonance imaging and cognitive assessment. A second, parallel study, the African American DHS, has expanded the sample of African Americans to investigate marked racial differences in subclinical CVD between European Americans and African Americans. Studies in development will evaluate the impact of social stress during the lifecourse on CVD risk, and the prevalence of gastroparesis in this diabetes enriched sample. In addition, the ongoing high mortality rate in DHS participants provides novel insights into the increased risks for type 2 diabetes affected individuals. A comprehensive genetic analysis of the sample is underway using the genome-wide association study (GWAS) approach. Data from this GWAS survey will complement prior family-based linkage data in the analysis of genetic contributors to the wide range of traits in the sample. To our knowledge the DHS family of studies has created the most comprehensively examined sample of individuals with type 2 diabetes yet available, and represents a unique resource for the study people with type 2 diabetes. The aim of this review is to provide a collective overview of the major results from the DHS family of studies, and relate them to the larger body of biomedical investigations of diabetes and its complications.

A study of the TNF/LTA/LTB locus and susceptibility to severe malaria in highland papuan children and adults

BACKGROUND

Severe malaria (SM) syndromes caused by Plasmodium falciparum infection result in major morbidity and mortality each year. However, only a fraction of P. falciparum infections develop into SM, implicating host genetic factors as important determinants of disease outcome. Previous studies indicate that tumour necrosis factor (TNF) and lymphotoxin alpha (LTα) may be important for the development of cerebral malaria (CM) and other SM syndromes.

METHODS

An extensive analysis was conducted of single nucleotide polymorphisms (SNPs) in the TNF, LTA and LTB genes in highland Papuan children and adults, a population historically unexposed to malaria that has migrated to a malaria endemic region. Generated P-values for SNPs spanning the LTA/TNF/LTB locus were corrected for multiple testing of all the SNPs and haplotype blocks within the region tested through 10,000 permutations. A global P-value of < 0.05 was considered statistically significant.

RESULTS

No associations between SNPs in the TNF/LTA/LTB locus and susceptibility to SM in highland Papuan children and adults were found.

CONCLUSIONS

These results support the notion that unique selective pressure on the TNF/LTA/LTB locus in different populations has influenced the contribution of the gene products from this region to SM susceptibility.

Galectin-2 3279TT variant protects against the lymphotoxin-alpha 252GG genotype associated ischaemic stroke

OBJECTIVE

The galectin-2 protein is presumed to play a regulatory role in the intracellular trafficking of the lymphotoxin-alpha (LTA) cytokine. LTA is a pro-inflammatory factor, its 252GG homozygote variant is considered as a susceptibility factor for arteriosclerosis and cardiovascular diseases. By contrast, the galectin-2-encoding gene LGALS2 3279TT homozygote variant has been demonstrated to exert protection against myocardial infarction by reducing the transcriptional level of galectin-2, thereby leading to a reduced extracellular secretion of LTA.

METHODS

In the present study, we examined whether the LGALS2 3279TT homozygote variant alone can influence the prevalence of ischaemic stroke, and whether it can interact somehow with the disadvantageous LTA 252GG homozygote variant. Genetic and clinical data of 385 ischemic stroke patients and 303 stroke and neuroimaging alteration-free controls were analysed.

RESULTS

The combination of the LGALS2 3279TT and LTA 252GG homozygote was significantly less frequent in the ischemic stroke group (1.56%) than in the controls (5.94%, p<0.00187; overall stroke group: crude OR: 0.25, 95% CI: 0.1-0.64; adjusted OR: 0.03, 95% CI: 0.025-0.71).

CONCLUSIONS

This finding suggests a gene-gene interaction.

Noninvasive measures of cardiovascular changes in diabetes mellitus

PURPOSE OF REVIEW

Advances in noninvasive medical technology have led to more aggressive pursuit of cardiovascular disease detection in patients with diabetes mellitus. Studies measuring carotid intima-media thickness, arterial stiffness and coronary artery calcification have documented early markers of cardiovascular disease. Such markers have gained popularity for research and clinical use. This paper reviews recent studies using noninvasive technology for detection and monitoring of cardiovascular disease as it pertains to diabetes patients.

RECENT FINDINGS

Studies published in the review period have utilized noninvasive techniques to monitor subclinical cardiovascular disease in diabetes patients, including carotid intima-media thickness to evaluate carotid atherosclerosis, pulse wave velocity and pulse wave analysis to measure arterial stiffness, electron beam computed tomography to evaluate coronary artery calcification, and magnetic resonance imaging to study cardiovascular plaque. These techniques have shown promising results and will have useful application for diabetes patients in the future.

SUMMARY

Noninvasive testing is being redefined to include new techniques for detection and monitoring of cardiovascular changes. In the appropriate clinical setting, these tests offer novel approaches to monitoring - each with its own benefits and caveats. Further refinement of techniques will lead to increased applicability and improved ability for early detection of subclinical cardiovascular disease.