Polymorphism at codon 469 of the intercellular adhesion molecule-1 gene is not associated with sporadic Alzheimer's disease

Association between polymorphism at codon 469 of the ICAM-1 gene and Henoch-Schönlein purpura in an Iranian cohort

Henoch-Schönlein purpura (HSP) is a common form of IgA1-mediated blood vessel inflammation affecting mainly children. Intercellular adhesion molecule-1 (ICAM-1) gene polymorphisms have been shown to be associated with HSP in different populations; in this study, we investigated its potential association and influence on the development of severe complications in Iranian HSP patients. Twenty-three patients diagnosed with IgAV/HSP according to the criteria of the American College of Rheumatology (ACR) with 53 age- and sex-matched control subjects were referred to us. Cases and controls were genotyped using Sanger sequencing. Based on our research data, we found an association between codon 469 K/E of the ICAM1 gene and risk of HSP. Our results revealed that KK genotype and allele K are more common in control than in the HSP group, therefore the subjects with KK genotype are protected against HSP. Our data also suggested that the genotype EE is associated with higher risk of HSP progression compared to KK genotype.

Untangling huge literature to disinter genetic underpinnings of Alzheimer's Disease: A systematic review and meta-analysis

Drug discovery for Alzheimer's Disease (AD) is channeled towards unravelling key disease specific drug targets/genes to predict promising therapeutic candidates. Though enormous literature on AD genetics is available, there exists dearth in data pertinent to drug targets and crucial pathological pathways intertwined in disease progression. Further, the research findings revealing genetic associations failed to demonstrate consistency across different studies. This scenario prompted us to initiate a systematic review and meta-analysis with an aim of unearthing significant genetic hallmarks of AD. Initially, a Boolean search strategy was developed to retrieve case-control studies from PubMed, Cochrane, ProQuest, Europe PMC, grey literature and HuGE navigator. Subsequently, certain inclusion and exclusion criteria were framed to shortlist the relevant studies. These studies were later critically appraised using New Castle Ottawa Scale and Q-Genie followed by data extraction. Later, meta-analysis was performed only for those Single Nucleotide Polymorphisms (SNPs) which were evaluated in at least two different ethnicities from two different reports. Among, 204,351 studies retrieved, 820 met our eligibility criteria and 117 were processed for systematic review after critical appraisal. Ultimately, meta-analysis was performed for 23 SNPs associated with 15 genes which revealed significant associations of rs3865444 (CD33), rs7561528 (BIN1) and rs1801133 (MTHFR) with AD risk.

Indices of low-grade chronic inflammation correlate with early cognitive deterioration in an elderly Greek population

Elevated serum levels of adhesion molecules (AM) reflect low-grade chronic inflammation and have been associated with several conditions of neuronal damage. The aim of the present study was the investigation of possible correlation between early cognitive decline and inflammatory processes in the elderly as indicated by plasma C-reactive protein (CRP) and AM levels. Thirty-seven subjects with dementia were selected from a community-dwelling, genetically isolated, geriatric population (above 60 years of age) based on the Mini Mental State Examination scale (MMSE) and the Diagnostic and Statistical Manual (DSM-IV) criteria. In parallel, a group of 33 age-matched healthy controls were selected from the same population. The levels of CRP (mg/l), sICAM-1 (ng/ml) and sVCAM-1 (ng/ml) were measured in the serum samples of both groups. Serum concentrations of all three molecules sICAM-1, sVCAM-1 and CRP were significantly higher in the dementia group when compared to controls (656.78 +/- 161.51 versus 467.05 +/- 231.26, p < 0.01; 631.64 +/- 149.76 versus 449.04 +/- 285.27, p < 0.01; 1.53 +/- 0.97 versus 0.7221 +/- 0.61, p < 0.01, respectively). Furthermore, a positive correlation was observed between the three molecules studied and the degree of severity of cognitive impairment. The findings of this study enhance the hypothesis of the presence of an underlying inflammatory process leading to cognitive deterioration and predisposing dementia in the elderly. The present work supports the evaluation of inflammatory molecules as early indicators of cognitive decline in elderly individuals.

Combinatorial Mismatch Scan (CMS) for loci associated with dementia in the Amish

BACKGROUND

Population heterogeneity may be a significant confounding factor hampering detection and verification of late onset Alzheimer's disease (LOAD) susceptibility genes. The Amish communities located in Indiana and Ohio are relatively isolated populations that may have increased power to detect disease susceptibility genes.

METHODS

We recently performed a genome scan of dementia in this population that detected several potential loci. However, analyses of these data are complicated by the highly consanguineous nature of these Amish pedigrees. Therefore we applied the Combinatorial Mismatch Scanning (CMS) method that compares identity by state (IBS) (under the presumption of identity by descent (IBD)) sharing in distantly related individuals from such populations where standard linkage and association analyses are difficult to implement. CMS compares allele sharing between individuals in affected and unaffected groups from founder populations. Comparisons between cases and controls were done using two Fisher's exact tests, one testing for excess in IBS allele frequency and the other testing for excess in IBS genotype frequency for 407 microsatellite markers.

RESULTS

In all, 13 dementia cases and 14 normal controls were identified who were not related at least through the grandparental generation. The examination of allele frequencies identified 24 markers (6%) nominally (p < or = 0.05) associated with dementia; the most interesting (empiric p < or = 0.005) markers were D3S1262, D5S211, and D19S1165. The examination of genotype frequencies identified 21 markers (5%) nominally (p < or = 0.05) associated with dementia; the most significant markers were both located on chromosome 5 (D5S1480 and D5S211). Notably, one of these markers (D5S211) demonstrated differences (empiric p < or = 0.005) under both tests.

CONCLUSION

Our results provide the initial groundwork for identifying genes involved in late-onset Alzheimer's disease within the Amish community. Genes identified within this isolated population will likely play a role in a subset of late-onset AD cases across more general populations. Regions highlighted by markers demonstrating suggestive allelic and/or genotypic differences will be the focus of more detailed examination to characterize their involvement in dementia.

CD14 receptor polymorphism and Alzheimer's disease risk

Activation of microglial cells is involved in the inflammatory component of Alzheimer's disease (AD), and it may be triggered by infectious pathogens. CD14, a receptor upregulated in activated microglia, plays a central role in innate immunity through recognition of bacterial lipopolysaccharide and initiation of inflammatory response. A polymorphism in the promoter region (-260) of the CD14 receptor has been found to be related to increased risk of bacterial infections and inflammatory diseases such as atherosclerosis. In a case-control study utilizing a clinically well-defined group of 310 sporadic AD patients and 310 control subjects, we investigated whether the CD14 (-260) polymorphism might be responsible for susceptibility to AD, and we also examined the combined gene effects between CD14 and APOE and several other proinflammatory cytokine genes. The current study does not demonstrate an association between CD14 (-260) polymorphism and AD, neither through an independent effect nor through interaction with APOE epsilon4 allele or interleukin (IL)-1A, IL-6, IL-8, tumor necrosis factor (TNF)-alpha, and intercellular adhesion molecule-1 polymorphisms.