Recent Consanguinity and Outbred Autozygosity Are Associated With Increased Risk of Late-Onset Alzheimer’s Disease

Prior work in late-onset Alzheimer’s disease (LOAD) has resulted in discrepant findings as to whether recent consanguinity and outbred autozygosity are associated with LOAD risk. In the current study, we tested the association between consanguinity and outbred autozygosity with LOAD in the largest such analysis to date, in which 20 LOAD GWAS datasets were retrieved through public databases. Our analyses were restricted to eight distinct ethnic groups: African–Caribbean, Ashkenazi–Jewish European, European–Caribbean, French–Canadian, Finnish European, North-Western European, South-Eastern European, and Yoruba African for a total of 21,492 unrelated subjects (11,196 LOAD and 10,296 controls). Recent consanguinity determination was performed using FSuite v1.0.3, according to subjects’ ancestral background. The level of autozygosity in the outbred population was assessed by calculating inbreeding estimates based on the proportion (FROH) and the number (NROH) of runs of homozygosity (ROHs). We analyzed all eight ethnic groups using a fixed-effect meta-analysis, which showed a significant association of recent consanguinity with LOAD (N = 21,481; OR = 1.262, P = 3.6 × 10–4), independently of APOE∗4 (N = 21,468, OR = 1.237, P = 0.002), and years of education (N = 9,257; OR = 1.274, P = 0.020). Autozygosity in the outbred population was also associated with an increased risk of LOAD, both for FROH (N = 20,237; OR = 1.204, P = 0.030) and NROH metrics (N = 20,237; OR = 1.019, P = 0.006), independently of APOE∗4 [(FROH, N = 20,225; OR = 1.222, P = 0.029) (NROH, N = 20,225; OR = 1.019, P = 0.007)]. By leveraging the Alzheimer’s Disease Sequencing Project (ADSP) whole-exome sequencing (WES) data, we determined that LOAD subjects do not show an enrichment of rare, risk-enhancing minor homozygote variants compared to the control population. A two-stage recessive GWAS using ADSP data from 201 consanguineous subjects in the discovery phase followed by validation in 10,469 subjects led to the identification of RPH3AL p.A303V (rs117190076) as a rare minor homozygote variant increasing the risk of LOAD [discovery: Genotype Relative Risk (GRR) = 46, P = 2.16 × 10–6; validation: GRR = 1.9, P = 8.0 × 10–4]. These results confirm that recent consanguinity and autozygosity in the outbred population increase risk for LOAD. Subsequent work, with increased samples sizes of consanguineous subjects, should accelerate the discovery of non-additive genetic effects in LOAD.

Pharmacogenetic profiling for oxaliplatin-based adjuvant chemotherapy (CT) benefit in stage II-III colon cancer (CC) patients: A GEMCAD study.

3618 Background: Identifying molecular biomarkers for tumour recurrence is critical in successfully selecting early-stage CC patients who are more likely to benefit from adjuvant CT. We tested whether single nucleotide polymorphisms (SNP) within genes involved in biological pathways of interest for CC progression and treatment resistance would predict the risk of recurrence in stage II-III CC patients treated with oxaliplatin and fluoropyrimidines-based adjuvant CT. Methods: Genomic DNA was extracted from formalin-fixed paraffin-embedded samples from 202 surgically treated high-risk stage II (29.7%) and stage III (70.29%) CC patients receiving adjuvant CT (25.24% FOLFOX, 74.75% XELOX) from January 2004 to December 2008. Minimum follow-up was 36 months. Genotyping was performed for 62 SNPs in 31 genes using the MassARRAY (SEQUENOM) technology. Our results were validated in an independent cohort of 177 stage II-III CC. Results: After a median follow-up of 51.4 months (7-96), 63 patients (31.18%) had experienced a relapse and 31 (15.34%) had died. Three-year disease-free survival (DFS) and overall survival (OS) were 72.2% (+/-0.032) and 89.1% (+/-0.022), respectively. Multivariate analysis showed that the risk of recurrence for patients with the E-selectine rs3917412 G>A G/G genotype was higher than for those with any A allele genotype [relative risk (RR): 2.02, 95% confidence interval (CI): 1.09-3.73, p=0.024]. In haplotype analysis, patients harboring the E-selectine rs3917412 G>A G/G and methylentetrahydrofolate reductase (MTHFR) rs1801133 C>T T/T haplotype had a higher risk of developing tumor recurrence compared to the E-selectine rs3917412 G>A any A and/or MTHFR rs1801133 C>T any C haplotype (RR: 3.39, 95% CI, 1.51-7.62, p=0.003). The ability to predict recurrence of this combined analysis was independently validated in the second cohort (RR: 3.75, 95% CI, 1.32-10.68, p=0.013). Conclusions: E-selectine and MTHFR SNPs were found to be independent prognostic markers for stage II-III CC patients, suggesting that this combined analysis provides additional prognostic information to that offered by clinicopathologic variables.

MDM2 SNP309 Is Associated With Poor Outcome in B-Cell Chronic Lymphocytic Leukemia

Purpose A single nucleotide polymorphism (SNP) at position 309 in the promoter region of MDM2 leading to increased expression of MDM2 and attenuated function of p53 has been negatively associated with onset and outcome of disease in solid tumors. Because inactivation of p53 by deletion and/or mutations also impacts on the clinical course of B-cell chronic lymphocytic leukemia (B-CLL), we assessed the role of the SNP309 genotype in B-CLL. Patients and Methods The frequency of SNP309 T/T, T/G, or G/G genotypes and the p53 status (wild type, mutated, or deleted) were assessed and correlated with clinical outcome in 140 B-CLL patients and a second independent cohort. In addition, the correlation of the MDM2 SNP309 genotype with the MDM2 protein expression level in B-CLL cells was evaluated by immunoblotting. Results A significant negative association of the SNP309 T/G and G/G genotypes with overall survival was seen (T/G genotype, relative risk = 3.7; 95% CI, 1.2 to 11.5; P = .02; G/G genotype, relative risk = 9.1; 95% CI, 2.4 to 35.1; P = .001), but no correlation with incidence or onset of B-CLL was observed. The influence of the heterozygous SNP309 T/G genotype on treatment-free survival depended on the p53 status but not on the CD38, Zap-70, or IgVH mutational status or Rai stage of B-CLL patients. The unfavorable SNP309 T/G and G/G genotypes were associated with a gene-dosage–dependent increase of MDM2 expression. Conclusion The MDM2 SNP309 genotype influencing MDM2 expression levels was identified as an additional independent risk factor in B-CLL. Targeting MDM2-p53 interactions might emerge as a successful treatment strategy for B-CLL.

Factor V Q506 (Resistance to Activated Protein C) and Prognosis after Acute Coronary Syndrome

SummaryFactor V:Q506 causing resistance to activated protein C (APC-resistance), is a risk factor for venous thrombosis. Some studies have indicated an association with arterial disease, especially in women. We investigated the prevalence of the FV:Q506 allele prospectively in 295 patients with acute coronary syndrome. Mortality and myocardial infarction rate were evaluated after 30 days and after 2 years. The FV:Q506 allele was found in 38 patients. In a Cox proportional hazards model, smokers carrying FV:Q506 had a higher risk of infarction or death within 30 days, compared to non-smokers with a normal genotype (relative risk 2.9 [95% CI 1.2-7.0]). The difference remained significant after 2 years (relative risk 2.8 [95% CI 1.2-6.5]). The effect of the FV:Q506 allele on clinical outcome in acute coronary syndrome has not previously been described. Our results demonstrate a gene-environment interaction between smoking and the FV:Q506 allele, with an increased risk of early complications after an acute ischemic event.