The complex facilitates histone deacetylation and downstream gene silencing from the methylated CpG site.

Histone methylation can result in either gene activation or repression, depending on the specific lysine or arginine that is modified.11 Another family of enzymes, the histone demethylases, such as lysine-specific demethylase 1 (LSD1), are capable of removing this methyl Inhibitors,research,lifescience,medical group from the lysine residues of histone and nonhistone proteins.12 A hallmark of non-Mendelian disease, discordance of monozygotic (MZ) twins, has traditionally been attributed to differential environmental factors activating a disease state in one of the genetically predisposed cotwins13; however, very few of these factors have been identified. Alternately, MZ twin discordance may be due to the partial stability of epigenetic factors, as diseaserelevant epigenetic dissimilarity can accumulate Inhibitors,research,lifescience,medical quite readily between cotwins.5,14,15 Another non-Mendelian peculiarity,

sexual dimorphism, is the differential susceptibility to a disease between males and females. It is observed in many psychiatric Silmitasertib in vivo conditions, such as Alzheimer’s disease, schizophrenia, alcoholism, and mood and anxiety disorders.16 Although the exact mechanism by which they predispose or protect from a disease is currently unknown, Inhibitors,research,lifescience,medical there is a great deal of evidence that sex hormones exert control of gene expression via epigenetic modifications; thus it is hypothesized that sexual dimorphism in many disease states may be the result of sex hormone-induced differences in the epigenetic status of key genes.17,18 Furthermore, the degree of risk for acquiring certain complex diseases may depend Inhibitors,research,lifescience,medical on the sex of the affected parent, as in schizophrenia,19 Alzheimer’s disease (AD),20 autism,21 and bipolar disorder (BD).22 Genomic imprinting, an epigenetic mechanism in which differential epigenetic modification of genes occurs depending on their parental origin,23 is Inhibitors,research,lifescience,medical thought to be the source of such parent-of-origin

effects. Diseases affecting cell growth, development, and behavior may result from disruption of the normal imprinting pattern.24 MTMR9 In the epigenetic model of complex disease, it is assumed that a primary epigenetic disruption takes place during the maturation of the germline, and this pre-epimutation increases an organism’s risk of acquiring a disease. The pre-epimutation may be tolerated and it may not be sufficient to cause the disease itself, but with time, perhaps even decades, small misregulations add up until a threshold is crossed and the individual experiences phenotypic changes that meet diagnostic criteria for a clinical disorder. The age of disease onset may depend on the effects of tissue differentiation, stochastic factors, hormones, and likely some external environmental factors (nutrition, infections, medications, addictions, etc).