Genetic Variants at the 9p21.3 Locus Are Associated with Risk for Non-Compressible Artery Disease: Results from the ARTPER Study.

Peripheral artery disease (PAD) and non-compressible artery disease (NCAD) constitute predictors of subclinical atherosclerosis easily assessed through the ankle brachial index (ABI). Although both diseases show substantial genetic influences, few genetic association studies have focused on the ABI and PAD, and none have focused on NCAD. To overcome these limitations, we assessed the role of several candidate genes on the ABI, both in its continuous distribution and in the clinical manifestations associated to its extreme values: PAD and NCAD. We examined 13 candidate genomic regions in 1606 participants from the ARTPER study, a prospective population-based cohort, with the ABI assessed through ultrasonography. Association analyses were conducted independently for individuals with PAD (ABI < 0.9) or with NCAD (ABI > 1.4) vs. healthy participants. After including potential covariates and correction for multiple testing, minor alleles in the genetic markers rs10757278 and rs1333049, both in the 9p21.3 region, were significantly associated with a decreased risk of NCAD. Associations with the ABI showed limited support to these results. No significant associations were detected for PAD. The locus 9p21.3 constitutes the first genetic locus associated with NCAD, an assessment of subclinical atherosclerosis feasible for implementation in primary healthcare settings that has been systematically neglected from genetic studies.

Sex-Specific Protective Effects of APOE ε2 on Cognitive Performance.

Apolipoprotein E (APOE) has an important role in the multiple trajectories of cognitive aging. However, environmental variables and other genes mediate the impact of APOE on cognition. Our main objective was to analyze the effect of APOE genotype on cognition and its interactions and relationships with sex, age, lipid profile, C-reactive protein, and Brain-derived neurotrophic factor (BDNF) genotype in a sample of 648 healthy participants over 50 years of age with a comprehensive neuropsychological assessment. Our results showed that APOE ε2 carriers performed better in the Verbal Memory (p = .002) and Fluency Domains (p = .001). When we studied the effect of sex, we observed that the beneficial effect of APOE ε2 on the normalized values of these cognitive domains occurred only in females (ß = 0.735; 95% confidence interval, 0.396-1.074; p = 3.167·10-5 and ß = 0.568; 95% confidence interval, 0.276-0.861; p = 1.853·10-4, respectively). Similarly, the sex-specific effects of APOE ε2 were further observed on lipidic and inflammation biomarkers. In the whole sample, APOE ε2 carriers showed significantly lower levels of total cholesterol, low-density lipoprotein cholesterol, and C-reactive protein. These differences were found only among females. Furthermore, total cholesterol and low-density lipoprotein cholesterol mediated the protective effect of APOE ε2 on cognition in the whole sample and total cholesterol in females, providing candidate physiological mechanisms for the observed genetic effects. Our results show that the neuroprotective role of APOE ε2 in cognition varies with sex and that the lipidic profile partially mediates this protection. Age-related cognitive and functional decline is a continuous biological process with different cognitive trajectories (1). Complex interactions between heritability, environmental influence, and cognitive functions in aging have been highlighted (2). In particular, genetic differences explain around 15%-25% of the variance in life expectancy (3). Therefore, the identification of susceptibility genes and their biological effects on cognitive aging is required to establish interindividual differences in this process and promote early personalized interventions to delay cognitive decline and minimize the financial burden of aging in the health care system.

Impact of the COMT Val108/158 Met and DAT genotypes on prefrontal function in healthy subjects.

Two limiting factors of dopamine activity are the catechol-o-methyltransferase (COMT) and the dopamine transporter (DAT), which terminate dopamine activity by degradation and uptake, respectively. Genetic variants of COMT and DAT have been related to the enzymatic activity and protein availability, respectively. The Met allele of the COMT Val108/158 Met polymorphism has been associated to lower enzymatic activity and the 9-repeat allele of the DAT 40 base-pair (bp) variable number of tandem repeat (VNTR) polymorphism has been related to lower protein availability. Genotypes for COMT and DAT were determined in a sample of 75 healthy subjects, who underwent functional magnetic resonance imaging (fMRI) while performing an N-back task. To further assess the effects of the genotypes on cognition, subjects were administered the Wisconsin Card Sorting Test (WCST) and the Continuous Performance Test (CPT). Analysis of fMRI data revealed an additive effect of these two genes on brain activation in an N-back task, with subjects homozygous for the Val and the 9-repeat alleles showing the highest activation for the same level of performance. Moreover, the Val allele was related to higher number of perseverative errors on the WCST and with a higher number of commission errors on the CPT. The 10-repeat allele was associated with faster reaction times but also with a higher number of commission errors. Our results support a role of the COMT Val108/158 Met and the DAT 40 bp VNTR in both brain activation and cognition.