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VTRNA2-1 is a polymorphically imprinted locus. The proportion of individuals with a maternally imprinted VTRNA2-1 locus is consistently approximately 75% in populations of European origin, with the remaining circa 25% having a non-methylated VTRNA2-1 locus. Recently, VTRNA2-1 hypermethylation at birth was suggested to be a precursor of paediatric acute lymphoblastic leukaemia with biomarker potential. The results presented by Ghantous et al. [1] allow for an alternative interpretation to what the authors discussed, and we argue that the observed methylation difference at birth is due to an uneven distribution of imprinted and non-methylated individuals among the cases and controls, with all individuals presenting normative physiological VTRNA2-1 methylation levels. In addition, the notable interindividual variation arising from the polymorphic imprinting in VTRNA2-1 methylation levels calls into question the validity of VTRNA2-1 methylation as a biomarker.

Background Ageing displays clear sexual dimorphism, evident in both morbidity and mortality. Ageing is also associated with changes in DNA methylation, but very little focus has been on the sex chromosomes, potential biological contributors to the observed sexual dimorphism. Here, we sought to identify DNA methylation changes associated with ageing in the Y and X chromosomes, by utilizing datasets available in data repositories, comprising in total of 1240 males and 1191 females, aged 14–92 years. Results In total, we identified 46 age-associated CpG sites in the male Y, 1327 age-associated CpG sites in the male X, and 325 age-associated CpG sites in the female X. The X chromosomal age-associated CpGs showed significant overlap between females and males, with 122 CpGs identified as age-associated in both sexes. Age-associated X chromosomal CpGs in both sexes were enriched in CpG islands and depleted from gene bodies and showed no strong trend towards hypermethylation nor hypomethylation. In contrast, the Y chromosomal age-associated CpGs were enriched in gene bodies, and showed a clear trend towards hypermethylation with age. Conclusions Significant overlap in X chromosomal age-associated CpGs identified in males and females and their shared features suggest that despite the uneven chromosomal dosage, differences in ageing-associated DNA methylation changes in the X chromosome are unlikely to be a major contributor of sex dimorphism in ageing. While age-associated CpGs showed good replication across datasets in the present study, only a limited set of previously reported age-associated CpGs were replicated. One contributor to the limited overlap are differences in the age range of individuals included in each data set. Further study is needed to identify biologically significant age-associated CpGs in the sex chromosomes.

In humans, the nc886 locus is a polymorphically imprinted metastable epiallele. Periconceptional conditions have an effect on the methylation status of nc886, and further, this methylation status is associated with health outcomes in later life, in line with the Developmental Origins of Health and Disease (DOHaD) hypothesis. Animal models would offer opportunities to study the associations between periconceptional conditions, nc886 methylation status and metabolic phenotypes further. Thus, we set out to investigate the methylation pattern of the nc886 locus in non-human mammals. We obtained DNA methylation data from the data repository GEO for mammals, whose nc886 gene included all three major parts of nc886 and had sequency similarity of over 80% with the human nc886. Our final sample set consisted of DNA methylation data from humans, chimpanzees, bonobos, gorillas, orangutangs, baboons, macaques, vervets, marmosets and guinea pigs. In human data sets the methylation pattern of nc886 locus followed the expected bimodal distribution, indicative of polymorphic imprinting. In great apes, we identified a unimodal DNA methylation pattern with 50% methylation level in all individuals and in all subspecies. In Old World monkeys, the between individual variation was greater and methylation on average was close to 60%. In guinea pigs the region around the nc886 homologue was non-methylated. Results obtained from the sequence comparison of the CTCF binding sites flanking the nc886 gene support the results on the DNA methylation data. Our results indicate that unlike in humans, nc886 is not a polymorphically imprinted metastable epiallele in non-human primates or in guinea pigs, thus implying that animal models are not applicable for nc886 research. The obtained data suggests that the nc886 region may be classically imprinted in great apes, and potentially also in Old World monkeys, but not in guinea pigs.

Preterm birth (PTB) is associated with increased risk of type 2 diabetes and neurocognitive impairment later in life. We analyzed for the first time the associations of PTB with blood miRNA levels in adulthood. We also investigated the relationship of PTB associated miRNAs and adulthood phenotypes previously linked with premature birth. Blood MicroRNA profiling, genome-wide gene expression analysis, computer-based cognitive testing battery (CANTAB) and serum NMR metabolomics were performed for Young Finns Study subjects (aged 34–49 years, full-term n = 682, preterm n = 84). Preterm birth (vs. full-term) was associated with adulthood levels of hsa-miR-29b-3p in a fully adjusted regression model (p = 1.90 × 10 –4 , FDR = 0.046). The levels of hsa-miR-29b-3p were down-regulated in subjects with PTB with appropriate birthweight for gestational age (p = 0.002, fold change [FC] = − 1.20) and specifically in PTB subjects with small birthweight for gestational age (p = 0.095, FC = − 1.39) in comparison to individuals born full term. Hsa-miR-29b-3p levels correlated with the expressions of its target-mRNAs BCL11A and CS and the gene set analysis results indicated a target-mRNA driven association between hsa-miR-29b-3p levels and Alzheimer's disease , Parkinson's disease , Insulin signaling and Regulation of Actin Cytoskeleton pathway expression. The level of hsa-miR-29b-3p was directly associated with visual processing and sustained attention in CANTAB test and inversely associated with serum levels of VLDL subclass component and triglyceride levels. In conlcusion, adult blood levels of hsa-miR-29b-3p were lower in subjects born preterm. Hsa-miR-29b-3p associated with cognitive function and may be linked with adulthood morbidities in subjects born preterm, possibly through regulation of gene sets related to neurodegenerative diseases and insulin signaling as well as VLDL and triglyceride metabolism.

Human endogenous retroviruses (HERV) are relics of ancient retroviral infections in our genome. Most of them have lost their coding capacity, but proviral RNA or protein have been observed in several disease states (e.g. in inflammatory and autoimmune diseases and malignancies). However, their clinical significance as well as their mechanisms of action have still remained elusive. As human aging is associated with several biological characteristics of these diseases, we now analyzed the aging-associated expression of the individual proviruses of two HERV families, HERV-K (91 proviruses) and HERV-W (213 proviruses) using genome-wide RNA-sequencing (RNA-seq). RNA was purified from blood cells derived from healthy young individuals (n = 7) and from nonagenarians (n = 7). The data indicated that in the case of HERV-K (HML-2) 33 proviruses had a detectable expression but in only 3 of those the expression levels were significantly different between the young and old individuals. In the HERV-W family expression was observed in 45 loci and only in one case the young/old difference was significant. However, applying hierarchical clustering on the HERV expression data resulted in the formation of two distinct clusters, one containing the young individuals and another the nonagenarians. This suggests, that even though the aging-associated differences in the expression levels of individual proviruses are minor, there seems to be some underlying aging-related pattern. These data indicate that aging does not have a strong effect on the expression of individual HERV proviruses, but instead several proviruses are affected moderately, leading to age-dependent expression profiles.

We analysed whole blood genome-wide expression data to identify gene co-expression modules shared by early traits of osteoporosis and atherosclerosis. Gene expression was profiled for the Young Finns Study participants. Bone mineral density and content were measured as early traits of osteoporosis. Carotid and bulbus intima media thickness were measured as early traits of atherosclerosis. Joint association of the modules, identified with weighted co-expression analysis, with early traits of the diseases was tested with multivariate analysis. Among the six modules significantly correlated with early traits of both the diseases, two had significant (adjusted p-values (p.adj) < 0.05) and another two had suggestively significant (p.adj < 0.25) joint association with the two diseases after adjusting for age, sex, body mass index, smoking habit, alcohol consumption, and physical activity. The three most significant member genes from the significant modules were NOSIP, GXYLT2, and TRIM63 (p.adj ≤ 0.18). Genes in the modules were enriched with biological processes that have separately been found to be involved in either bone metabolism or atherosclerosis. The gene modules and their most significant member genes identified in this study support the osteoporosis-atherosclerosis comorbidity hypothesis and can provide new joint biomarkers for both diseases and their dual prevention.

Evidence is accumulating on the connection of early adversities and harsh family environment with epigenetic ageing. We investigated whether early psychosocial resilience is associated with epigenetic ageing in adulthood. We used the population‐based Young Finns data (n = 1593). Early psychosocial resilience was assessed in 1980–1989 across five broad domains: (1) index of psychological strength (self‐esteem at home/in general/at school, perceived possibilities to influence at home, internal life control), (2) index of social satisfaction (perceived support from family/friends and life satisfaction), (3) index of leisure time activities (hobbies and physical fitness), (4) index of responsible health behaviors (infrequent smoking or alcohol consumption), and (5) index of school career (school grades and adaptation). Epigenetic ages were calculated for blood samples from 2011, and the analyses were performed with variables describing age deviation (AgeDevHannum, AgeDevHorvath, AgeDevPheno, AgeDevGrim) and DunedinPACE. Covariates included early family environment, polygenic risk scores for schizophrenia and major depression, adulthood education, and adulthood health behaviors. All of the early resilience indexes were associated with lower levels of epigenetic ageing in adulthood, most consistently with AgeDevGrim and DunedinPACE. The associations of psychological strength and social satisfaction, in particular, seemed to be non‐linear. In a smaller subsample (n = 289), high early resilience was related to lower AgeDevGrim over a 25‐year follow‐up in those who had high “baseline” levels of AgeDevGrim. In conclusion, early resilience seems to associate with lower level of epigenetic ageing in adulthood. Our results tentatively suggest that early resilience may increase “equality in epigenetic ageing” in a general population. Various domains of early psychosocial resilience were associated with lower epigenetic ageing in the population‐based sample of the Young Finns Study. Our results tentatively suggest that early resilience may increase “equality in epigenetic ageing” in a general population.

Background Sleep disturbances are known to have adverse effects on health, but knowledge on the effect of sleep disturbances on epigenetic ageing is limited. We investigated (1) whether symptoms of insomnia, obstructive sleep apnoea, sleep deprivation, and circadian rhythm lateness are associated with epigenetic ageing, and (2) whether years spent in shift work moderates these associations. Methods We used the population-based Young Finns data ( n  = 1618). Epigenetic clocks such as AgeDev Hannum , AgeDev Horvath , AgeDev Pheno , AgeDev Grim , and DunedinPACE were utilized to measure epigenetic ageing. Sleep was evaluated using various validated self-report questionnaires. Covariates included sex, array type, smoking status, health behaviours, socioeconomic factors, and cardiovascular health factors. Results Among the various sleep measures, obstructive sleep apnoea symptoms were most consistently linked to accelerated epigenetic ageing, as measured by AgeDev Grim and DunedinPACE. Insomnia, sleep deprivation, and years spent in shift work were not associated with epigenetic ageing after adjusting for health-related or socioeconomic covariates. Additionally, we found interactions between years spent in shift work and sleep disturbances when accounting for epigenetic ageing. Among those with little to no history of shift work, both insomnia and sleep deprivation were associated with more accelerated epigenetic ageing in AgeDev Grim when compared to long-term shift workers. However, the pace of epigenetic ageing (measured with DunedinPACE) appears to be higher in those with both sleep deprivation and longer history of shift work. Conclusions Among various sleep measures, symptoms of obstructive sleep apnoea appear to be most consistently associated with accelerated epigenetic ageing even after adjusting for various health-related and socioeconomic factors. Shift work seems to have a crucial role in the relationship between sleep disturbances and epigenetic ageing in working-age adults.

Aging and gender have a strong influence on the functional capacity of the immune system. In general, the immune response in females is stronger than that in males, but there is scant information about the effect of aging on the gender difference in the immune response. To address this question, we performed a transcriptomic analysis of peripheral blood mononuclear cells derived from elderly individuals (nonagenarians, n = 146) and young controls (aged 19-30 years, n = 30). When compared to young controls, we found 339 and 248 genes that were differentially expressed (p<0.05, fold change >1.5 or <-1.5) in nonagenarian females and males, respectively, 180 of these genes were changed in both genders. An analysis of the affected signaling pathways revealed a clear gender bias: there were 48 pathways that were significantly changed in females, while only 29 were changed in males. There were 24 pathways that were shared between both genders. Our results indicate that female nonagenarians have weaker T cell defenses and a more prominent pro-inflammatory response as compared to males. In males significantly fewer pathways were affected, two of which are known to be regulated by estrogen. These data show that the effects of aging on the human immune system are significantly different in males and females.

The increased paternal age at conception (PAC) has been associated with autism spectrum disorder (ASD), schizophrenia and other neurodevelopmental disorders, thus raising questions that imply, potential health concerns in the offspring. As opposed to female oogonia, the male germ cells undergo hundreds of cell divisions during the fertile years. Thus, the advanced paternal age is associated with increase of point mutations in the male spermatogonia DNA, implying that this could be the major driving mechanism behind the paternal age effect observed in the offspring. In addition to replication errors, DNA replication fidelity and inefficient DNA repair machinery in the spermatogonia also contribute to the mutagenic load. Our study population consisted of 38 nonagenarians, participants in the Vitality 90+ Study, born in the year 1920 (women n = 25, men n = 13), for whom the parental birth dates were available. The gene expression profile of the study subjects was determined with HumanHT-12 v4 Expression BeadChip from peripheral blood mononuclear cells. We used Spearman's rank correlation to look for the associations of gene expression with paternal age at conception. Associated transcripts were further analyzed with GOrilla and IPA to determine enriched cellular processes and pathways. PAC was associated with the expression levels of 648 transcripts in nonagenarian subjects. These transcripts belonged to the process of mitochondrial translational termination and the canonical pathway of Mitochondrial dysfunction, more specifically of Oxidative phosphorylation. The observed systematic down-regulation of several mitochondrial respiratory chain components implies compromised function in oxidative phosphorylation and thus in the production of chemical energy.