Article

Genetics Meets Environment: Evaluating Gene-Environment Interactions in Neurologic Diseases

Toronto Western Hospital, University of Toronto, Ontario, Canada.
Seminars in Neurology (Impact Factor: 1.78). 11/2011; 31(5):553-61. DOI: 10.1055/s-0031-1299793
Source: PubMed

ABSTRACT The vast majority of disease is due to complex relationships between genetic and environmental factors. Single genetic or environmental causes are rare. Unfortunately, this presents major challenges for assessing disease risk in individuals. Further complicating the situation is the fact that there are many ways in which genetic and environmental determinants can combine to cause disease. This review explores the concepts of gene-environment interaction to provide a basic understanding of the principles of interactions and approaches to studying them. Collaborations between genetics and environmental experts will be crucial to understand the complex relationships.

0 Followers
 · 
84 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Essential metals are crucial for the maintenance of cell homeostasis. Among the 23 elements that have known physiological functions in humans, 12 are metals, including iron (Fe) and manganese (Mn). Nevertheless, excessive exposure to these metals may lead to pathological conditions, including neurodegeneration. Similarly, exposure to metals that do not have known biological functions, such as mercury (Hg), also present great health concerns. This reviews focuses on the neurodegenerative mechanisms and effects of Fe, Mn and Hg. Oxidative stress (OS), particularly in mitochondria, is a common feature of Fe, Mn and Hg toxicity. However, the primary molecular targets triggering OS are distinct. Free cationic iron is a potent pro-oxidant and can initiate a set of reactions that form extremely reactive products, such as OH•. Mn can oxidize dopamine (DA), generating reactive species and also affect mitochondrial function, leading to accumulation of metabolites and culminating with OS. Cationic Hg forms have strong affinity for nucleophiles, such as -SH and -SeH. Therefore, they target critical thiol- and selenol-molecules with antioxidant properties. Finally, we address the main sources of exposure to these metals, their transport mechanisms into the brain, and therapeutic modalities to mitigate their neurotoxic effects. Keywords: Manganese; iron; mercury; oxidative stress; glutathione.
    Neurochemistry International 12/2012; 62(5). DOI:10.1016/j.neuint.2012.12.006 · 2.65 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Methylmercury (MeHg) is an environmental toxicant that leads to long-lasting neurological and developmental deficits in animals and humans. Although the molecular mechanisms mediating MeHg-induced neurotoxicity are not completely understood, several lines of evidence indicate that oxidative stress represents a critical event related to the neurotoxic effects elicited by this toxicant. The objective of this review is to summarize and discuss data from experimental and epidemiological studies that have been important in clarifying the molecular events which mediate MeHg-induced oxidative damage and, consequently, toxicity. Although unanswered questions remain, the electrophilic properties of MeHg and its ability to oxidize thiols have been reported to play decisive roles to the oxidative consequences observed after MeHg exposure. However, a close examination of the relationship between low levels of MeHg necessary to induce oxidative stress and the high amounts of sulfhydryl-containing antioxidants in mammalian cells (e.g., glutathione) have led to the hypothesis that nucleophilic groups with extremely high affinities for MeHg (e.g., selenols) might represent primary targets in MeHg-induced oxidative stress. Indeed, the inhibition of antioxidant selenoproteins during MeHg poisoning in experimental animals has corroborated this hypothesis. The levels of different reactive species (superoxide anion, hydrogen peroxide and nitric oxide) have been reported to be increased in MeHg-exposed systems, and the mechanisms concerning these increments seem to involve a complex sequence of cascading molecular events, such as mitochondrial dysfunction, excitotoxicity, intracellular calcium dyshomeostasis and decreased antioxidant capacity. This review also discusses potential therapeutic strategies to counteract MeHg-induced toxicity and oxidative stress, emphasizing the use of organic selenocompounds, which generally present higher affinity for MeHg when compared to the classically studied agents.
    Toxicology and Applied Pharmacology 05/2011; 256(3):405-17. DOI:10.1016/j.taap.2011.05.001 · 3.63 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The most common diseases affecting middle-aged and elderly subjects in industrialized countries are multigenetic and lifestyle related. Several attempts have been made to study interactions between genes and lifestyle factors, but most such studies lack the power to examine interactions between several genes and several lifestyle components. The primary objective of the EpiHealth cohort study is to provide a resource to study interactions between several genotypes and lifestyle factors in a large cohort (the aim is 300,000 individuals) derived from the Swedish population in the age range of 45-75 years regarding development of common degenerative disorders, such as cardiovascular diseases, cancer, dementia, joint pain, obstructive lung disease, depression, and osteoporotic fractures. The study consists of three parts. First, a collection of data on lifestyle factors by self-assessment using an internet-based questionnaire. Second, a visit to a test center where blood samples are collected and physiological parameters recorded. Third, the sample is followed for occurrence of outcomes using nationwide medical registers. This overview presents the study design and some baseline characteristics from the first year of data collection in the EpiHealth study.
    European Journal of Epidemiology 02/2013; 28(2). DOI:10.1007/s10654-013-9787-x · 5.15 Impact Factor