Age-related macular degeneration-susceptibility single nucleotide polymorphisms in a han chinese control population

Proteomic genotyping of SNP of Complement Factor H (CFH) Y402H and I62V using multiple reaction monitoring (MRM) assays

The single nucleotide polymorphisms (SNPs) of complement factor H (CFH) gene are well-known genetic risk factors for age-related macular degeneration (AMD). To identify whether the measurement of plasma protein concentrations of CFH variants using the multiple reaction monitoring (MRM) assay can determine the genotypes of CFH SNP rs1061170 and rs800292, 120 patients with AMD and 26 controls were included in this study. The number of cases were TT:TC:CC = 121:24:1 in CFH SNP Y402H and GG:AG:AA = 72:57:17 in CFH SNP I62V. Plasma concentrations of tryptic peptides were measured using the MRM assay, and tyrosine/histidine (Y/H) and valine/isoleucine (V/I) CFH variant protein ratios were obtained. To discriminate the genotypes by the plasma protein ratios, cut-off values were set for Y/H ratios (TT: > 4.428; TC: 1.00-4.428; CC: < 1.00) and V/I ratios (GG: > 1.09; AG: 0.0089-1.08; AA: < 0.0089). Correlation analysis revealed that the plasma CFH variant protein ratios and genotypes of CFH were exactly matched (100%) without overlap in the total patients and controls. The measurement of plasma protein CFH variants using the MRM assay can accurately identify the genotypes of CFH SNPs of Y402H and I62V.

MicroRNA binding mediated Functional sequence variant in 3'-UTR of DNA repair Gene XPC in Age-related Cataract

DNA oxidative damage repair is strongly involved in the pathogenesis of age-related cataract (ARC). The sequence variants of in coding region of DNA repair genes have been shown to be associated with ARC. It is known that single nucleotide polymorphisms (SNPs) in the 3′-terminal untranslated region (3′-UTR) can alter the gene expression by binding with microRNAs (miRNAs). We hypothesize that SNP(s) in miRNA binding site of certain DNA oxidative damage repair genes might associate with ARC risk. We examined 10 miRNA binding SNPs in 3′-UTR of 7 oxidative damage genes and revealed the XPC- rs2229090 C allele was associated with nuclear type of ARC (ARNC) risk in Chinese population. The individuals with the variant G allele (CG and GG) of XPC- rs2229090 had higher XPC mRNA expression compared to individuals carrying CC genotype. The in vitro assay showed that luciferase reporter gene expression can be down regulated by hsa-miR-589-5p in cells transfected with rs2229090 C allele compared to G allele. These results suggested that the C allele of XPC-2229090 increase the risk with ARNC. The mechanism underlying might be due to the stronger interation of the C allele with hsa-miR-589-5p, resulting in lower XPC expression and DNA repair capability than the individuals carring G allele in lens.

Polymorphisms in the microglial marker molecule CX3CR1 affect the blood volume of the human brain

AIM

CX3CR1, a G-protein-coupled receptor, is involved in various inflammatory processes. Two non-synonymous single nucleotide polymorphisms, V249I (rs3732379) and T280M (rs3732378), are located in the sixth and seventh transmembrane domains of the CX3CR1 protein, respectively. Previous studies have indicated significant associations between T280M and leukocyte functional characteristics, including adhesion, signaling, and chemotaxis, while the function of V249I is unclear. In the brain, microglia are the only proven and widely accepted CX3CR1-expressing cells. This study aimed to specify whether there were specific brain regions on which these two single nucleotide polymorphisms exert their biological impacts through their functional effects on microglia.

METHODS

Associations between the single nucleotide polymorphisms and brain characteristics, including gray and white matter volumes, white matter integrity, resting arterial blood volume, and cerebral blood flow, were evaluated among 1300 healthy Japanese individuals.

RESULTS

The major allele carriers (V249 and T280) were significantly associated with an increased total arterial blood volume of the whole brain, especially around the bilateral precuneus, left posterior cingulate cortex, and left posterior parietal cortex. There were no significant associations between the genotypes and other brain structural indicators.

CONCLUSION

This finding suggests that the CX3CR1 variants may affect arterial structures in the brain, possibly via interactions between microglia and brain microvascular endothelial cells.

MiR-2964a-5p binding site SNP regulates ATM expression contributing to age-related cataract risk

This study was to explore the involvement of DNA repair genes in the pathogenesis of age-related cataract (ARC). We genotyped nine single nucleotide polymorphisms (SNPs) of genes responsible to DNA double strand breaks (DSBs) in 804 ARC cases and 804 controls in a cohort of eye diseases in Chinese population and found that the ataxia telangiectasia mutated (ATM) gene-rs4585:G>T was significantly associated with ARC risk. An in vitro functional test found that miR-2964a-5p specifically down-regulated luciferase reporter expression and ATM expression in the cell lines transfected with rs4585 T allele compared to rs4585 G allele. The molecular assay on human tissue samples discovered that ATM expression was down-regulated in majority of ARC tissues and correlated with ATM genotypes. In addition, the Comet assay of cellular DNA damage of peripheral lymphocytes indicated that individuals carrying the G allele (GG/GT) of ATM-rs4585 had lower DNA breaks compared to individuals with TT genotype. These findings suggested that the SNP rs4585 in ATM might affect ARC risk through modulating the regulatory affinity of miR-2964a-5p. The reduced DSBs repair might be involved in ARC pathogenesis.

Functional SNP in 3'-UTR MicroRNA-Binding Site of ZNF350 Confers Risk for Age-Related Cataract

Many studies have suggested that individual susceptibility to age-related cataract (ARC) may be associated with DNA sequence polymorphisms affecting gene regulation. As DNA repair is implicated in ARC pathogenesis and single-nucleotide polymorphisms (SNPs) in the 3'-terminal untranslated region (3'-UTR) targeted by microRNAs (miRNAs) can alter the gene function, we hypothesize that the miRNA-binding SNPs (miRSNPs) in DNA double-strand break repair (DSBR) and nucleotide excision repair (NER) pathways might associate with ARC risk. We genotyped nine miRSNPs of eight genes in DSBR and NER pathways in Chinese population and found that ZNF350- rs2278414:G>A was significantly associated with ARC risk. Even though the Comet assay of cellular DNA damage indicated that all the subtypes of ARC patients had more DNA breaks in peripheral lymphocytes than the controls independent of rs2278414 genotypes, individuals carrying the variant A allele (AA and AG) had lower ZNF350 mRNA levels compared with individuals with GG genotype. Moreover, the in vitro experiment indicated that miR-21-3p and miR-150-5p specifically downregulated luciferase reporter expression in the cell lines transfected with rs2278414 A allele compared with rs2278414 G. These results suggested that the association of SNP rs2278414 with ARC might involve an altered miRNA regulation of ZNF350.

Association of CX3CR1 (V249I and T280M) polymorphisms with age-related macular degeneration: a meta-analysis

OBJECTIVE

Studies investigating the associations between CX3CR1 genetic polymorphisms and age-related macular degeneration (AMD) have reported controversial results. Therefore, this meta-analysis aims to clarify the effects of CX3CR1 T280M and V249I polymorphisms on AMD risk.

DESIGN

Meta-analysis.

PARTICIPANTS

Results from six studies were pooled in the meta-analysis.

METHODS

Relevant studies were selected through an extensive search of PubMed, EMBASE, and the Web of Science databases. Pooled odds ratio (OR) and 95% confidence interval (CI) were calculated using random-effects model.

RESULTS

Six studies with were included in this systematic review and meta-analysis. There was no significant association between CX3CR1 T280M polymorphism and risk of AMD under all genetic models (TT vs

CC/CT

OR = 1.57, 95% CI = 0.87-2.84; CC vs TT/CT: OR = 0.75, 95% CI = 0.54-1.06; TT vs CC: OR = 0.58, 95% CI = 0.30-1.144; CT vs CC: OR = 1.25, 95% CI = 0.91-1.70). The CX3CR1 V249I polymorphism also did not significantly affect the AMD risk (AA vs

GG/AG

OR = 1.23, 95% CI = 0.98-1.55; AG/AA vs GG: OR = 0.56, 95% CI = 0.29-1.07; AA vs GG: OR = 1.43, 95% CI = 0.97-2.09; AG vs GG: OR = 1.07, 95% CI = 0.85-1.36).

CONCLUSIONS

This meta-analysis suggested that CX3CR1 T280M and V249I polymorphisms may not be associated with an increased risk of AMD based on current published data. Given the limited sample size, the finding on CX3CR1 polymorphisms needs further investigation.

Genetic insights into age-related macular degeneration: controversies addressing risk, causality, and therapeutics

Age-related macular degeneration (AMD) is a common condition among the elderly population that leads to the progressive central vision loss and serious compromise of quality of life for its sufferers. It is also one of the few disorders for whom the investigation of its genetics has yielded rich insights into its diversity and causality and holds the promise of enabling clinicians to provide better risk assessments for individuals as well as to develop and selectively deploy new therapeutics to either prevent or slow the development of disease and lessen the threat of vision loss. The genetics of AMD began initially with the appreciation of familial aggregation and increase risk and expanded with the initial association of APOE variants with the disease. The first major breakthroughs came with family-based linkage studies of affected (and discordant) sibs, which identified a number of genetic loci and led to the targeted search of the 1q31 and 10q26 loci for associated variants. Three of the initial four reports for the CFH variant, Y402H, were based on regional candidate searches, as were the two initial reports of the ARMS2/HTRA1 locus variants. Case-control association studies initially also played a role in discovering the major genetic variants for AMD, and the success of those early studies have been used to fuel enthusiasm for the methodology for a number of diseases. Until 2010, all of the subsequent genetic variants associated with AMD came from candidate gene testing based on the complement factor pathway. In 2010, several large-scale genome-wide association studies (GWAS) identified genes that had not been previously identified. Much of this historical information is available in a number of recent reviews (Chen et al., 2010b; Deangelis et al., 2011; Fafowora and Gorin, 2012b; Francis and Klein, 2011; Kokotas et al., 2011). Large meta analysis of AMD GWAS has added new loci and variants to this collection (Chen et al., 2010a; Kopplin et al., 2010; Yu et al., 2011). This paper will focus on the ongoing controversies that are confronting AMD genetics at this time, rather than attempting to summarize this field, which has exploded in the past 5 years.