The brain-derived neurotrophic factor (BDNF) gene Val66Met polymorphism affects memory performance in older adults

Objective: Memory impairment is an important contributor to the reduction in quality of life experienced by older adults, and genetic risk factors seem to contribute to variance in age-related cognitive decline. Brain-derived neurotrophic factor (BDNF) is an important nerve growth factor linked with development and neural plasticity. The Val66Met polymorphism in the BDNF gene has been associated with impaired episodic memory in adults, but whether this functional variant plays a role in cognitive aging remains unclear. The purpose of this study was to investigate the effects of the BDNF Val66Met polymorphism on memory performance in a sample of elderly adults. Methods: Eighty-seven subjects aged > 55 years were recruited using a community-based convenience sampling strategy in Porto Alegre, Brazil. The logical memory subset of the Wechsler Memory Scale-Revised was used to assess immediate verbal recall (IVR), delayed verbal recall (DVR), and memory retention rate. Results: BDNF Met allele carriers had lower DVR scores (p = 0.004) and a decline in memory retention (p = 0.017) when compared to Val/Val homozygotes. However, we found no significant differences in IVR between the two groups (p = 0.088). Conclusion: These results support the hypothesis of the BDNF Val66Met polymorphism as a risk factor associated with cognitive impairment, corroborating previous findings in young and older adults.

Efectos del polimorfismo Val108/158Met del gen dopaminérgico Catecol-O-metiltransferasa COMT en las funciones ejecutivas de preescolares / Effects of dopamine gene polymorphism Val108/158Met Catechol-O-methyltransferase COMT in executive functions in preschool

El nivel de Dopamina en la Corteza Prefrontal se ha relacionado al desempeño de las Funciones Ejecutivas (FE). El objetivo de este estudio es explorar el efecto del polimorfismo funcional del gen COMT (Val/Val,Val/Met y Met/Met) en las FE de preescolares. Se utilizó la Batería Neuropsicológica de Funciones Ejecutivas para niños, y se extrajo el ADN genómico según metodología estándar (N=248) de 3 a 6 años de edad (M=4.6). Se estudiaron las frecuencias genotípicas del gen COMT y se realizó un análisis de varianza (ANOVA one-way) estableciendo diferencias significativas con una p<0.05. Los niños con el polimorfismo de baja actividad Met/Met puntúan significativamente mejor en relación a los niños con polimorfismo Val/Val en pruebas que requieren de Inhibición y los niños con el polimorfismo de alta actividad Val/Val resultan con un mejor rendimiento en pruebas relacionadas a MT, Planeación y Abstracción que los niños con polimorfismo Met/Met y Val/Met. Estos resultados parecen reflejar el papel de la enzima COMT como regulador de DA y que tanto el hipermetabolismo como el hipometabolismo tiene implicaciones importantes en las FE.

The level of DA in the prefrontal cortex has been related to the performance on executive functions (EF). The objective of this study was to explore the effect of the COMT polymorphism (Val/Val, Val/Met, Met/Met) in the performance of EF in a population of preschool children. All subjects were evaluated with a Neuropsychological Battery and genomic DNA was extracted according to standard methodology (N=248) from 3 to 6 years of age (M=4.6). We studied genotypic frequencies of the COMT gene and an analysis of variance (one-way ANOVA) with post hoc analysis, establishing significant differences at p<0.05. In Children with a low activity polymorphism Met/Met scored significantly better in relation to the children with polymorphism Val/Val in tests requiring inhibition and children with high activity polymorphism Val/Val had better performance on tests related to working memory, planning and abstraction that children with polymorphism Met/Met and Val/Met. These results seem to reflect the role of COMT enzyme as a regulator of DA and that both hypermetabolism and hypometabolism has important implications for the EF.

Age-dependent dichotomous effect of superoxide dismutase Ala16Val polymorphism on oxidized LDL levels

We investigated the association between superoxide dismutase (SOD) Ala16Val polymorphism and the levels of oxidized LDL lipoprotein-C (ox-LDL-C) in two age-different Greek cohorts. Four hundred fifteen middle-aged (n=147 females: 43.2+/-13 years, n=268 males: 43.3+/-14 years) Caucasian Greek subjects consisted the middle aged cohort. One hundred seventy five elderly (n=88 females: 79.9+/-4 years; n=87 males: 80.6+/-4 years) were selected from the elderly cohort. Genotype data were obtained for all of them. Multiple linear regression analysis, stratified by gender and adjusted for age, smoking habits and body mass index as covariates, showed higher ox-LDL-C levels for the middle aged men with the Val/Val genotype, compared to the other allele (Ala/Ala and Ala/Val) carriers (65.9+/-25.7 vs. 55.7+/-20.5 mg/dl; standardized beta coefficient=0.192, P=0.012). On the contrary, elderly women with the Val/Val genotype occurred with lower ox-LDL-C levels compared to the Ala/Ala or Ala/Val genotype (74.2+/-22.1 vs. 86.5+/-26.6 mg/dl; standardized beta coefficient= -0.269, P=0.015). The same trend was also recorded in elderly men, however without reaching statistical significance (standardized b coefficient= -0.187, P=0.077). Moreover, elderly men and women with the Ala/Ala or Ala/Val genotype presented higher triglycerides levels compared to Val/Val (women: 145.2+/-68.7 vs. 114.3+/-34.3 mg/dl, P= 0.027; men: 147.8+/-72.4 vs. 103.7 +/-38.0 mg/dl, P=0.002). Additionally, middle aged men with the Val/Val genotype had higher HDL-C levels compared to the Ala allele carriers. The results suggest that SOD Ala16Val polymorphism is an age-dependent modulator of ox-LDL-C levels in middle-aged men and elderly women.

Association of Leu125Val polymorphism of platelet endothelial cell adhesion molecule-1 (PECAM-1) gene & soluble level of PECAM-1 with coronary artery disease in Asian Indians.

BACKGROUND & OBJECTIVES: Platelet endothelial cell adhesion molecule-1 (PECAM-1) plays a key role in the transendothelial migration of circulating leukocytes (diapedesis) during vascular inflammation. We hypothesized that genetic variation and the level of soluble PECAM-1 could be associated with the development of atherosclerosis and conducted a study on gene polymorphisms of PECAM-1 and soluble PECAM-1 levels in Asian Indian patients with coronary artery disease (CAD) in Singapore. METHODS: Of the 137 angiographically confirmed patients (> or =70% stenosis) of CAD and 110 controls in Asian Indian population, two single nucleotide polymorphisms (SNPs) of PECAM-1 gene, C+373G (Leu125Val) at exon 3 and G+1688A (Ser563Asn) at exon 8 were analyzed by polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) strategy. In addition, plasma soluble PECAM-1, P-selection and lipid profile were measured. Chi- square test and student t test were adopted to compare categorical and continuous variables, respectively. RESULTS: A significant decrease in C allele frequency but increase in G allele frequency of the Leu125Val (C/G) polymorphism were observed in CAD patients as compared with controls (0.54/0.46 vs 0.663/0.337 respectively, P=0.008). Alteration in genotype distributions (CC, CG and GG) of the Leu125Val polymorphism between CAD patients and controls (P=0.009) was also significant. A similar trend was observed on the allele frequencies (G/A) and genotype distributions of Ser563Asn (G/A) polymorphism, though the difference did not reach significance. On the other hand, plasma level of soluble PECAM-1 (sPECAM-1) was markedly elevated in CAD patients (P=0.006), and associated with soluble P-selectin and lipid profiles. INTERPRETATION & CONCLUSION: Our study showed that Leu125Val polymorphism of PECAM-1 gene and elevated soluble PECAM-1 were related to severe coronary artery stenosis in CAD patients of Asian Indian origin in Singapore. Our data also suggest that PECAM-1 plays an important role in the development of atherosclerosis.

Effects of Val34Leu and Val35Leu polymorphism on the enzyme activity of the coagulation factor XIII-A

Change in fibrin stabilizing activity of factor XIII A subunit (FXIII-A) caused by a specific mutation, Val34Leu, is recently implicated to incidences of pathophysiology of thrombosis. In an effort to understand the effect of Val34Leu on enhanced catalytic role of FXIII-A, wild type human factor XIII A (HFXIII-A) and mutant HFXIII-A: HFXIII-A (V34L), HFXIII-A (V35L) and HFXIII-A (V34L/V35L) cDNA were expressed in E.coli system where the purified recombinant FXIII-A (rFXIII-A) showed a similar specific transglutaminase activity comparable to the human native FXIII-A from platelet. Using these rFXIII-A mutants, the activation kinetics by thrombin and the enzymatic properties of the activated rFXIII-A were characterized. rFXIII-A (V34L) and rFXIII-A (V34L/V35L) mutants were activated by thrombin much faster than those of wild type rFXIII-A and V35L variant. However, the activated rFXIII-A and mutants showed the identical catalytic efficiency as measured by in vitro assay. These results suggest that ready activation caused by a specific mutation of neighboring thrombin cleavage site(s) in the activation peptide of FXIII-A like V34L resulted in the real-time amount of the activated factor XIII-A that could influence the outcome of fibrin stabilization in vivo such as alpha2- plasmin inhibitor crosslinking to fibrin, a reaction known to be dependent on the initial concentration of active factor-XIII-A.

No Association of Factor XIII Val34Leu Polymorphism with Primary Intracerebral Hemorrhage and Healthy Controls in Korean Population

The polymorphism in the factor XIII A-subunit gene (FXIII Val34Leu) has been recognized as a risk factor for primary intracerebral hemorrhage (PICH). In addition, FXIII Val34Leu has a significant ethnic heterogeneity. FXIII Val34Leu was detected in 41.7-54.8% of the Westerners, but in 2.5% of the Asians. We aimed to evaluate the prevalence of FXIII Val34Leu in patients with PICH and in healthy controls among Koreans. We recruited 58 in-patients with PICH, defined by brain computed tomography or magnetic resonance imaging, and 48 controls matched for age, sex, and risk factors for cerebrovascular diseases. Genomic DNA was extracted from blood. A 183-bp fragment of exon 2/intron B of the factor XIII Asubunit gene was amplified by polymerase chain reaction (PCR). The factor XIII genotype was determined through a single-stranded conformational polymorphism. Fifty-eight patients and 48 controls showed the same band patterns on SSCP. In addition, we directly sequenced six random-selected DNA segments using DNA auto-sequencer. In conclusion, the results of this study suggest that FXIII Val34Leu be absent or rare both in patients with PICH and in healthy controls among Koreans.