PICALM and CR1 Variants are not Associated with Sporadic Alzheimer's Disease in Chinese Patients

Department of Neurology and Institute of Neurology, Huashan Hospital, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Shanghai Medical College, Fudan University, Shanghai, China.
Journal of Alzheimer's disease: JAD (Impact Factor: 4.15). 02/2011; 25(1):111-7. DOI: 10.3233/JAD-2011-101917
Source: PubMed


Alzheimer's disease (AD) is the most common form of senile dementia, and the overall prevalence increases exponentially with age. It is well known that genetic variants may play an important role in the pathogenesis of this disorder. Recently, two independent large-scale genome-wide association studies (GWAS) identified 3 novel single nucleotide polymorphisms (SNPs) (rs11136000 within CLU, rs3851179 within PICALM and rs6656401 within CR1) that are associated with late-onset AD (LOAD), and these results have been replicated by other studies performed in the Caucasian population. Recently, an independent study failed to verify the association for the SNP within CLU in a Han Chinese population, indicating that there may be genetic heterogeneity in this association. In the present study, we studied the SNPs within PICALM and CR1 in 474 sporadic AD patients (SAD) and 591 unrelated age- and sex-matched healthy controls of Han Chinese descent. Our data revealed that the frequencies of both of these SNPs were not significantly difference between the SAD and control groups. Thus, the association between SNPs within PICALM, CR1, and SAD should be studied further in different ethnic groups.

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    • "c o m / l o ca t e / n e u a g i n g Furthermore, in 1 genome-wide association study (GWAS) carried out by Lambert et al. among subjects recruited from France, Finland, Belgium, Spain, and Italy, results demonstrated significant association between single nucleotide polymorphisms (SNPs) in CR1 and LOAD (Lambert et al., 2009). Since the first observation, numerous groups have examined the role of CR1 genetic variation with AD risk (Carrasquillo et al., 2010; Chen et al., 2012; Ferrari et al., 2012; Keenan et al., 2012; Li et al., 2011) , but the results have been equivocal, suggesting that there may be genetic heterogeneity in their association. In our pilot study of 254 LOAD patients and 357 healthy control subjects (Zhang et al., 2010), we have shown significant association of CR1 and LOAD risk with a 2.6 unadjusted odds ratio for carrying the risk allele of the SNP rs6656401. "
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    ABSTRACT: Complement receptor 1 (CR1) has been considered to play an important role in late-onset Alzheimer's disease (LOAD) pathogenesis. To explore the correlation between the CR1 gene and LOAD, a 2-step design study was conducted in our Northern Han Chinese population. We first sequenced the promoter, exons, the 5' and 3' untranslated regions and exon-intron boundaries of CR1 in a small sample (n = 100). This allowed us to identify a total of 22 variants. In addition, 6 missense variants within the CR1 gene were selected to be genotyped in a total of 2292 individuals. Only 2 SNPs (rs116806486, Thr→Ala; rs6691117, Ile→Val) were significantly associated with an increased risk of LOAD. After stratification by APOE ε4-carrying status, significance was observed in APOE ε4 non-carriers for rs116806486 and in APOE ε4 carriers for rs6691117. Logistic analysis revealed that the rs116806486 polymorphism remained associated with LOAD in a dominant model, whereas the rs6691117 polymorphism was associated with LOAD in additive and recessive models but not in a dominant model after adjusting for sex, age at onset, and APOE ε4 status. Examination of the haplotypes identified the risk of a 3-SNP (rs2274567, rs3737002, and rs6691117) haplotype "ATG" in CR1 was associated with an increased risk for LOAD. These findings provide the evidence that missense variants in the CR1 gene may be involved in LOAD pathologic process in Han Chinese.
    Full-text · Article · Sep 2013 · Neurobiology of aging
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    ABSTRACT: Classical population genetics shows that varying permutations of genes and risk factors permit or disallow the effects of causative agents, depending on circumstance. For example, genes and environment determine whether a fox kills black or white rabbits on snow or black ash covered islands. Risk promoting effects are different on each island, but obscured by meta-analysis or GWAS data from both islands, unless partitioned by different contributory factors. In Alzheimer's disease, the foxes appear to be herpes, borrelia or chlamydial infection, hypercholesterolemia, hyperhomocysteinaemia, diabetes, cerebral hypoperfusion, oestrogen depletion, or vitamin A deficiency, all of which promote beta-amyloid deposition in animal models—without the aid of gene variants. All relate to risk factors and subsets of susceptibility genes, which condition their effects. All are less prevalent in convents, where nuns appear less susceptible to the ravages of ageing. Antagonism of the antimicrobial properties of beta-amyloid by Abeta autoantibodies in the ageing population, likely generated by antibodies raised to beta-amyloid/pathogen protein homologues, may play a role in this scenario. These agents are treatable by diet and drugs, vitamin supplementation, pathogen detection and elimination, and autoantibody removal, although again, the beneficial effects of individual treatments may be tempered by genes and environment.
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    ABSTRACT: Recently, an international genome-wide association study (GWAS) additionally found rs597668 near EXOC3L2/BLOC1S3/MARK4 was a new genome-wide significance locus associated with late-onset Alzheimer's disease (LOAD) in Caucasians. Follow-up replication studies were conducted almost exclusively in Caucasians, and the effects of the risk locus in other populations are as yet unknown. This study investigated the GWAS-associated locus near EXOC3L2 in 1205 unrelated Northern Han Chinese subjects comprising 598 LOAD patients and 607 healthy controls matched for gender and age. The results showed no significant differences in the genotypic or allelic distributions of rs597668 polymorphism between LOAD cases and healthy controls (genotype: P=0.653; allele: P=0.603), even after stratification for apolipoprotein E (APOE) ɛ4 status and statistical adjustment for age, gender and APOE ɛ4 status. This study suggests that the rs597668 polymorphism near EXOC3L2 may not play a major role in the susceptibility to LOAD in the Northern Han Chinese population.
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