Biology subjects

Demanelis, K.

Publications and source records attributed to Demanelis, K..

3 recordsLinked to original sources

bioRxiv2019

Determinants of telomere length across human tissues

Telomere shortening is a hallmark of aging. Telomere length (TL) in blood cells has been studied extensively as a biomarker of human aging and disease; however, little is known regarding variability in TL in non-blood, disease-relevant tissue types. Here we characterize variability in TL measurements for 6,391 tissue samples, representing >20 tissue types and 952 individuals from the Genotype-Tissue Expression (GTEx) Project. We describe differences across tissue types, positive correlation among tissue types, and associations with age and ancestry. We show that genetic variation impacts TL in multiple tissue types, and that TL can mediate the effect of age on gene expression. Our results provide the foundational knowledge regarding TL in healthy tissues that is needed to interpret epidemiological studies of TL and human health.\n\nONE SENTENCE SUMMARYTelomere length varies by tissue type but is generally correlated among tissue types (positively) and with age (negatively).

genetics↗

bioRxiv2019

Genetically Increased Telomere Length and Aging-related Physical and Cognitive Traits in the UK Biobank

BackgroundTelomere length (TL) shortens over time in most human cell types and is a potential biomarker aging. However, the causal impact of TL on physical and cognitive phenotypes that decline with age has not been extensively examined. Using a Mendelian randomization (MR) approach, we utilized genetically increased TL (GI-TL) to estimate the impact of TL on aging-related traits among UK Biobank (UKB) participants. MethodsWe manually curated >50 aging-related traits from UKB and restricted to unrelated participants of British ancestry (n=337,522). We estimated GI-TL as a linear combination of nine TL-associated SNPs, each weighted by its previously-reported association with leukocyte TL. Regression models were used to assess the associations between GI-TL and each trait. We obtained MR estimates using the two-sample inverse variance weighted (IVW) approach. ResultsWe identified 5 age-related traits associated with GI-TL (Bonferroni-corrected threshold p<0.001): pulse pressure (PP) (p=5.2x10-14), systolic blood pressure (SBP) (p=2.9x10-15), diastolic blood pressure (DBP) (p=5.5x10-6), forced expiratory volume (FEV1) (p= p=0.0001), and forced vital capacity (FVC) (p=3.8x10-6). Under MR assumptions, one standard deviation increase in TL ([~]1200 base pairs) increased PP, SBP, and DBP by 1.5, 2.3, and 0.8 mmHg, respectively, while FEV1 and FVC increased by 34.7 and 52.2 mL, respectively. The observed associations appear unlikely to be due to selection bias based on analyses including inverse probability weights and analyses of simulated data. ConclusionsThese findings suggest that longer TL increases pulmonary function and blood pressure traits. Further research is necessary to evaluate TL in cardiovascular and pulmonary age-related decline. KEY MESSAGESO_LITelomere length (TL) is a potential biomarker and cause of aging, however, the causal relationship between TL and aging-related traits has not been thoroughly examined using a Mendelian randomization (MR) approach. C_LIO_LIWe evaluated genetically increased TL (GI-TL) and its association with over 50 aging-related traits in the UK Biobank cohort using regression models and MR approaches. C_LIO_LIPulmonary function (FEV1 and FVC) and blood pressure (SBP, DBP, and PP) traits were positively associated with GI-TL in the expected and unexpected direction, respectively. C_LIO_LIUsing inverse probability weights to account for the non-representativeness of the UKB, our observed associations for GI-TL with blood pressure traits and pulmonary function persisted. C_LIO_LIUsing simulated data to examine study selection as a potential source of collider bias, we concluded that selection bias was unlikely to explain the observed associations. C_LI

epidemiology↗

bioRxiv2018

The contribution of parent-to-offspring transmission of telomeres to the heritability of telomere length in humans

Leukocyte telomere length (LTL) is a heritable trait with two potential sources of heritability (h2): inherited variation in non-telomeric regions (e.g., SNPs that influence telomere maintenance) and variability in the lengths of telomeres in gametes that produce offspring zygotes (i.e., \"direct\" inheritance). Prior studies of LTL h2 have not attempted to disentangle these two sources. Here, we use a novel approach for detecting the direct inheritance of telomeres by studying the association between identity-by-descent (IBD) sharing at chromosome ends and phenotypic similarity in LTL. We measured genome-wide SNPs and LTL for a sample of 5,069 Bangladeshi adults with substantial relatedness. For each of the 7,254 relative pairs identified, we used SNPs near the telomeres to estimate the number of chromosome ends shared IBD, a proxy for the number of telomeres shared IBD (Tshared). We then estimated the association between Tshared and the squared pairwise difference in LTL (({Delta}LTL)2) within various classes of relatives (siblings, avuncular, cousins, and distant), adjusting for overall genetic relatedness ({phi}). The association between Tshared and ({Delta}LTL)2 was inverse among all relative pair types. In a meta-analysis including all relative pairs ({phi} >0.05), the association between Tshared and ({Delta}LTL)2 (P=0.002) was stronger than the association between {phi} and ({Delta}LTL)2 (P=0.45). Our results provide strong evidence that telomere length (TL) in parental germ cells impacts TL in offspring cells and contributes to LTL h2 despite telomere \"reprogramming\" during embryonic development. Applying our method to larger studies will enable robust estimation of LTL h2 attributable to direction transmission.

genetics↗