76 Of the CpG-rich regions analyzed, the majority were unmethylated, and it appears possible that very small alterations in methylation level could accumulate over time, ultimately affecting gene regulatory functions and causing disease. Age-related alteration of methylation status is a global phenomenon, not necessarily limited to particular disease susceptibility genes. Another study examined the methylation changes in 807 arbitrarily selected genes from two cohorts from Utah and Iceland, taking Inhibitors,research,lifescience,medical DNA samples at two timepoints from each subject,

spaced either 11 or 16 years apart. In these two populations, they observed time-dependent changes in global DNA methylation within the same individual, with 8% to 10% of individuals in showing changes that were greater than 20 percent; both gains and losses of methylation were detected.77 Similarly, the Boston Normative Aging Inhibitors,research,lifescience,medical Study measured DNA methylation in the blood of 718 elderly subjects (55 to 92 years of age) over a span of 8 years. A progressive

loss of DNA methylation in repetitive elements was found, particularly in Alu repeats, and this LY294002 linear decline highly correlated with Inhibitors,research,lifescience,medical time since the first measurement.78 A seemingly innocuous early-life epigenetic change in some critical gene involved in AD etiology, for example, the amyloid precursor protein (APP) locus, could potentially become pathologic when subjected to epigenetic drift as the subject ages. Although the molecular Inhibitors,research,lifescience,medical mechanisms leading to early-life methylation disturbances have not yet been identified, the possibility of early epimutation

and epigenetic drift should not be ignored as an etiological candidate Inhibitors,research,lifescience,medical for LOAD. Autism spectrum disorders Autism and related developmental disorders, such as Asperger’s and Rett syndromes, fall under the broader class of autism spectrum disorders (ASD), where “spectrum” reflects the observed continuum of severity or impairment experienced. These disorders become apparent in young children and persist into adulthood, with deficits in social cognition regarded as the most characteristic feature of ASD, leading to restrictions in social communication.79 While Idoxuridine autism itself is believed to have a particularly strong inherited basis relative to other developmental psychiatric syndromes,80 DNA sequence factors in the etiology of ASD are still largely unknown.81 Evidence supports a contribution of imprinted genes in ASD, as well as paternal transmission (reviewed in ref 82), and perhaps the combination of this information and the lack of identified genetic markers will stimulate future epigenetic and epigenomic studies of ASD.