The receptor for advanced glycation end-products (RAGE) has been implicated in several pathophysiological processes relevant to Alzheimer’s disease (AD), including transport and synaptotoxicity of AD-associated amyloid β (Aβ) peptides. A recent Chinese study (Li et al. in J Neural Transm 117:97–104, 2010) suggested an association between the 82S allele of the functional single nucleotide polymorphism (SNP) G82S (rs2070600) in the RAGE-encoding gene AGER and risk of AD. The present study aimed to investigate associations between AGER, AD diagnosis, cognitive scores and cerebrospinal fluid AD biomarkers in a European cohort of 316 neurochemically verified AD cases and 579 controls. Aside from G82S, three additional tag SNPs were analyzed to cover the common genetic variation in AGER. The 82S allele was associated with increased risk of AD (Pc = 0.04, OR = 2.0, 95% CI 1.2–3.4). There was no genetic interaction between AGER 82S and APOE ε4 in producing increased risk of AD (P = 0.4), and none of the AGER SNPs showed association with Aβ42, T-tau, P-tau181 or mini-mental state examination scores. The data speak for a weak, but significant effect of AGER on risk of AD.

Alzheimer's disease (AD) is characterized by protein aggregates, i.e. senile plaques and neurofibrillary tangles. The ubiquitin-proteasome system has been proposed a role in proteolytic removal of these protein aggregates. Ubiquitin carboxy-terminal hydrolase L1 (UCHL1) is a de-ubiquitinating enzyme with important functions in recycling of ubiquitin. The S18Y polymorphism of the UCHL1 gene confers protection against Parkinson's disease. In this study, the genotype and allele frequencies of the UCHL1 S18Y polymorphism were investigated in 452 AD patients and 234 control subjects, recruited from four memory clinics in Sweden. Using a binary logistic regression model including UCHL1 allele A and APOE ε4 allele positivity, age and sex as covariates with AD diagnosis as dependent variable, an adjusted OR of 0.82 ([95% CI 0.55-1.24], P = 0.35) was obtained for a positive UCHL1 allele A carrier status. The present study thus do not support a protective effect of the UCHL1 S18Y polymorphism against AD.

Kinesin is a microtubule-associated motor protein that transports Alzheimer-associated amyloid precursor protein (APP) in neurons. In animal models, impaired kinesin-mediated APP transport seems to enhance formation of the neurotoxic 42 amino acid fragment of ß-amyloid (Aß42). In man, one study suggests that a polymorphism (rs8702, 56,836G>C) in the kinesin light chain 1 gene (KNS2) may affect the risk of Alzheimer's disease (AD). To further assess KNS2 as a susceptibility gene for AD we analyzed 802 patients with sporadic AD and 286 controls, 134 longitudinally followed patients with mild cognitive impairment (MCI) and 39 cognitively stable controls for the rs8702 polymorphism. The rs8702 polymorphism did not influence risk of AD (p=0.46). However, rs8702 interacted with APOE ε4 carrier status in AD (p=0.006) and influenced cerebrospinal fluid levels of hyperphosphorylated tau in MCI patients who converted to AD during follow-up (p=0.018). These findings support earlier indications that genetic variability in the KNS2 gene may play a role during early stages of AD pathogenesis.

We found GSK3B gene variants associated with cognitive function and CSF biomarkers T-tau and Aβ42. To our knowledge, this is the first time GSK3B has been associated with cognitive function or CSF biomarkers reflecting neuronal degeneration (T-tau) and brain amyloid load (Aβ42). The regulation of GSK3B needs to be investigated further, to fully understand how these GSK3B gene variants are involved in AD pathogenesis.

Mannan-Binding lectin (MBL) is a serum lectin and an important constituent of the innate immune system. Processes linked to the innate immune response have previously been implicated in Alzheimer's disease (AD). MBL is associated with blood vessels in the brain and AD patients demonstrate lower MBL levels in the cerebrospinal fluid compared to controls. We investigated six single nucleotide polymorphisms, linked to MBL deficiency, in the corresponding MBL2 gene in AD patients and controls. Two MBL2 haplotypes, LXP and LYQ, were significantly associated with AD risk (OR = 1.6, p = 0.01 and OR = 1.5, p = 0.02, respectively). The present study is the first investigating MBL2 genotypes and haplotypes in relation to AD. Our findings support that the MBL2 gene impact the disease risk.