Salivary Telomere Length Research Articles

Simultaneous determination of salivary telomere length and mitochondrial DNA copy number in adolescent endurance athletes

Simultaneous determination of salivary telomere length and mitochondrial DNA copy number in adolescent endurance athletes

Telomere Length is Associated with the Prevalence, Persistence, and Incidence of Sarcopenia

Telomere length (TL) shortening has been identified as a marker of aging and associated with adverse health outcomes, but evidence of its association with sarcopenia is inconclusive. Estimate the cross-sectional and prospective associations between TL and sarcopenia. We used data from Waves 3 and 4 (2017, 2021) of the Study on Global Aging and Adult Health in Mexico (SAGE-Mexico). The cross-sectional sample consisted of 1,738 adults aged 50 and older, and the longitudinal sample consisted of 1,437. Relative TL was determined by real-time quantitative polymerase chain reaction (qPCR) on DNA extracted from saliva samples and quantified as the telomere/single-copy gene (T/S) ratio. Sarcopenia was defined according to the European Working Group on Sarcopenia in Older People (EWGSOP2). The mean salivary TL was 1.50 T/S units (95% CI: 1.49-1.52). The baseline prevalence of sarcopenia was 13.3% (95% CI: 9.8-16.8%). The incidence and persistence of sarcopenia were 6.8% (95% CI: 5.0-9.5%) and 7.0% (95% CI: 5.1-9.6%), respectively. The results showed that a one standard deviation decrease in TL was cross-sectionally associated with higher odds of sarcopenia (OR = 1.31; 95% CI: 1.03-1.67) and prospectively with a higher incidence (RRR = 1.55; 95% CI: 1.06-2.25) and persistence (RRR = 1.50; 95% CI: 1.01-2.24) of sarcopenia. Older adults with shorter TL had higher rates of incident and persistent sarcopenia. Implementation of interventions to delay the decline of TL in older adults is warranted. Further translational studies are needed to elucidate the effects of exercise or diet on DNA repair in the telomeric region and their associations with sarcopenia.

The long and the short of it: Salivary telomere length as a candidate biomarker for hypertension and age-related changes in blood pressure.

Hypertension becomes more prevalent with increasing age. Telomere length (TL) has been proposed as a candidate biomarker and can be accessibly extracted from saliva. However, clarity is needed to evaluate the suitability of using TL as a predictor in such instances. This study investigated salivary TL in a cohort of older adults from the 2008 Health and Retirement Study (n = 3329; F: 58%, mean age: 69.4, SD: 10.3 years) to examine any associations with blood pressure (BP). A Bayesian robust regression model was fit using weakly informative priors to predict the effects of TL with age, sex, systolic BP (SBP), diastolic BP (DBP), and treatment status. There were small effects of treatment (β: -0.07, 95% CrI [-0.33, 0.19], pd: 71.91%) and sex (β: -0.10, 95% CrI [-0.27, 0.07], pd: >86.78%). Population effects showed a reduction of 0.01 log2 units in TL with each year of advancing age (95% CrI [-0.01, -0.00]). Conditional posterior predictions suggest that females, and treated individuals, experience greater change in TL with increasing age. Bayes R2 was ~2%. TL declines with increasing age, differs between sexes, and appears to be influenced by antihypertensive drugs. Overall, all effects were weak. The data do not currently support the suitability of salivary TL as a biomarker to predict or understand any age-related changes in BP.

Characteristics of salivary telomere length shortening in preterm infants.

To examine the association between gestational age, telomere length (TL) and rate of shortening in newborns. Genomic DNA was isolated from buccal samples of 39 term infants at birth and one year and 32 preterm infants at birth, term-adjusted age (40 weeks post-conception) and age one-year corrected for gestational duration. Telomere length was measured by quantitative real-time PCR. Demographic and clinical data were collected during clinic or research visits and from hospital records. Socioeconomic status was estimated using the deprivation category (DEPCAT) scores derived from the Carstairs score of the subject's postal code. At birth, preterm infants had longer telomeres than infants born at term. However, there was no difference in telomere length between preterm infants and term infants at one year of age, implying that the rate of telomere shortening was greater in pre-term than term infants. Interestingly, TL at age 40 weeks post-conception in preterm infants was significantly longer than term infant TL at birth, suggesting that time since conception is not the only factor that affects rate of shortening. Several factors, including sex, fetal growth restriction, maternal age, maternal booking body mass index (BMI), mother education level and DEPCAT score, also differed between the preterm and term groups. Preterm infants have longer telomeres than term infants at birth. In the studied cohort, the rate of telomere shortening was greater in the premature group compared with the term infants. This finding agrees with previous studies using cord blood, suggesting that the longer TL in premature infants detected at birth do not persist and demonstrating that use of saliva DNA is acceptable for studies of telomere dynamics in infants. However, that the TL at age 40 weeks post-conception in preterm is longer than term infants at birth suggests that biological factors other than time since conception also affect rate of shortening.

Salivary telomere length and the risks of prediabetes and diabetes among middle-aged and older adults: findings from the Health and Retirement Study.

To assess the association of telomere length (TL) with prediabetes/diabetes and to explore the potential factors affecting TL among individuals with prediabetes/diabetes by weight status. This study included 3,379 eligible adults (aged 45-85years, males: 42%) from the US Health and Retirement Study in 2008. TL was assayed using quantitative PCR of saliva (T/S ratio). Linear and nonlinear associations between TL and prediabetes/diabetes were assessed using the logistic regression and restricted cubic spline model, respectively, adjusting for TL-plate numbers, age, sex, race, body mass index, lifestyles, diabetes medications, and cardiometabolic parameters (blood pressure, C-reactive protein, and total cholesterol). Multiple linear regression was used for testing any factors associated with TL. Among 3,379 participants, 868 (25.7%) had prediabetes with a mean TL of 1.34 ± 0.37 (T/S ratio) and 858 (25.4%) had diabetes with a mean TL of 1.36 ± 0.43 (T/S ratio). Neither linear nor nonlinear association of TL with prediabetes/diabetes was significant by weight status. Age was negatively associated with TL in both normal-weight (β = - 0.002, p = 0.025) and overweight/obese (β = - 0.002, p = 0.006) prediabetes, but non-significant in normal-weight and overweight/obese diabetes. BMI and cardiometabolic parameters were not associated with TL in prediabetes/diabetes by weight status. Salivary TL was not associated with prediabetes/diabetes among the US middle-aged and older adults. Further longitudinal studies are required to establish the link between TL and diabetes development and to identify potential factors affecting TL shortening, particularly in normal-weight diabetic patients.

How social/environmental determinants and inflammation affect salivary telomere length among middle-older adults in the health and retirement study

Social epidemiology posits that chronic stress from social determinants will lead to a prolonged inflammatory response that may induce accelerated aging as measured, for example, through telomere length (TL). In this paper, we hypothesize variables across demographic, health-related, and contextual/environmental domains influence the body’s stress response, increase inflammation (as measured through high-sensitivity C-reactive protein (hs-CRP)), and thereby lead to shortening of telomeres. This population-based research uses data from the 2008 Health and Retirement Study on participants ages ≤ 54–95 + years, estimating logistic regression and Cox proportional hazards models of variables (with and without confounders) across the domains on shortened TL. A mediation analysis is also conducted. Contrary to expectations, hs-CRP is not associated with risk of shortened TL. Rather, factors related to accessing health care, underlying conditions of frailty, and social inequality appear to predict risk of shorter TL, and models demonstrate considerable confounding. Further, hs-CRP is not a mediator for TL. Therefore, the social determinants of health examined do not appear to follow an inflammatory pathway for shortened TL. The finding of a relationship to social determinants affecting access to health care and medical conditions underscores the need to address social determinants alongside primary care when examining health inequities.

Social inequalities in accelerated aging among southern U.S. women: an analysis of the biosocial and behavioral pathways linking social determinants to telomere length

ABSTRACT Few studies have examined the biosocial pathways linking socioeconomic status (SES) to accelerated aging in a population-based sample of southern US women. Even fewer have examined the importance of chronic compared to perceived stress in linking SES to women’s salivary telomere length (STL). Using data from a probability-based sample of 156 US women and structural equation modeling, we examined three pathways – chronic stress exposure, stress appraisal, and coping behavior – linking SES to STL. SES was positively associated with STL (βTE = 0.16, p < .05). Everyday discrimination was negatively associated with STL (βDE = −0.21, p < .05), but perceived stress was positively associated with STL (βDE = 0.20, p < .05). Current smoking decreased STL (βDE = −0.19, p < .01). Perceived stress acted to suppress the negative relationship of chronic stress exposure on STL. Given the dearth of STL studies that include measures of both perceived and chronic stress, our study supports the importance of disentangling stress measures and a biosocial approach to the study of accelerated aging.

The correlation of salivary telomere length and single nucleotide polymorphisms of the ADIPOQ, SIRT1 and FOXO3A genes with lifestyle-related diseases in a Japanese population.

It has been reported that genetic factors are associated with risk factors and onset of lifestyle-related diseases, but this finding is still the subject of much debate. The aim of the present study was to investigate the correlation of genetic factors, including salivary telomere length and three single nucleotide polymorphisms (SNPs) that may influence lifestyle-related diseases, with lifestyle-related diseases themselves. In one year at a single facility, relative telomere length and SNPs were determined by using monochrome multiplex quantitative polymerase chain reaction and TaqMan SNP Genotyping Assays, respectively, and were compared with lifestyle-related diseases in 120 Japanese individuals near our university. In men and all participants, age was inversely correlated with relative telomere length with respective p values of 0.049 and 0.034. In men, the frequency of hypertension was significantly higher in the short relative telomere length group than in the long group with unadjusted p value of 0.039, and the difference in the frequency of hypertension between the two groups was of borderline statistical significance after adjustment for age (p = 0.057). Furthermore, in men and all participants, the sum of the number of affected lifestyle-related diseases, including hypertension, was significantly higher in the short relative telomere length group than in the long group, with p values of 0.004 and 0.029, respectively. For ADIPOQ rs1501299, men's ankle brachial index was higher in the T/T genotype than in the G/G and G/T genotypes, with p values of 0.001 and 0.000, respectively. For SIRT1 rs7895833, men's body mass index and waist circumference and all participants' brachial-ankle pulse wave velocity were higher in the A/G genotype than in the G/G genotype, with respective p values of 0.048, 0.032 and 0.035. For FOXO3A rs2802292, women's body temperature and all participants' saturation of peripheral oxygen were lower in the G/T genotype than in the T/T genotype, with respective p values of 0.039 and 0.032. However, relative telomere length was not associated with physiological or anthropometric measurements except for height in men (p = 0.016). ADIPOQ rs1501299 in men, but not the other two SNPs, was significantly associated with the sum of the number of affected lifestyle-related diseases (p = 0.013), by genotype. For each SNPs, there was no significant difference in the frequency of hypertension or relative telomere length by genotype. Relative telomere length and the three types of SNPs determined using saliva have been shown to be differentially associated with onset of and measured risk factors for lifestyle-related diseases consisting mainly of cardiovascular diseases and cancer.

Biopsychosocial Risk Profiles Among African American and Non-Hispanic White Adults: Findings From The Health and Retirement Study.

Compared to Whites, African Americans have elevated risk for earlier onset fatal and nonfatal chronic conditions and accelerated aging. Despite these persistent race disparities, the causes remain poorly understood. The purpose of this study was to define a biopsychosocial risk typology that might explain accelerated aging in African Americans. Analyses were based on the African American and White subsample of the Health and Retirement Study (N = 8269). Latent class analysis was used to identify risk types. Chronic health conditions, salivary telomere length (STL), emotional support from family, negative interaction with family, early life adversities, and discrimination were used as class indicators. Latent class multinomial logistic regression was used to identify racial and demographic differences in risk type membership. Three distinct risk types were identified: high risk, health risk, and psychosocial risk. African Americans were more likely than Whites to be assigned to the high-risk type characterized by chronic health conditions, shorter STL, strained social relationships and high psychosocial stress. African Americans were less likely than Whites to be assigned to the health risk type characterized by chronic health conditions, shorter STL, optimal social relationships, and low psychosocial stress. The biopsychosocial risk typology accounted for population heterogeneity, identified high-risk profiles, and modifiable factors within risk types that can inform current clinical interventions. The risk types also revealed different patterns of risk and resilience factors and shed light on the interplay between telomere length, stress exposure, chronic disease, and accelerated aging in African Americans.

Marital Quality and Salivary Telomere Length Among Older Men and Women in the United States.

Objective: The link between marital quality and cellular aging remains underexplored. This study examined how both positive and negative marital quality were associated with salivary telomere length among partnered adults in the United States over the age of 50°years. Methods: Data were from the 2008 Health and Retirement Study (N = 3203). Ordinary least squares regression was used to estimate the link between marital quality and telomere length. Results: While neither positive nor negative marital quality was significantly associated with telomere length among older women, positive and negative marital quality had an interacting effect on telomere length among men. Specifically, when negative marital quality was low, higher positive marital quality was associated with shorter telomere length, whereas when negative marital quality was high, higher positive marital quality was associated with longer telomere length. Discussion: The findings speak to the complex nature of intimate partnerships and the implications of these partnerships for cellular aging processes.

Association of sleep quality with telomere length, a marker of cellular aging: A retrospective cohort study of older adults in the United States

BackgroundSleep quality is a risk factor for age-related diseases, and although the underlying mechanisms remain unclear, the effects of poor sleep quality on telomere length (TL) may play a role. ObjectiveThe objective of the study was to evaluate the independent association between sleep quality and salivary TL in a large sample of older adults. DesignWe adopted a retrospective cohort design, and participants comprised 5,268 adults drawn from the Health and Retirement Study. We used the 2006 (baseline) and 2008 (follow-up) waves. Baseline sleep quality was assessed using 4 Likert scale questions (trouble falling asleep, waking up during the night, waking up too early and not being able to fall sleep again, and feeling well rested in the morning). The TL was assessed using the T/S ratio, a continuous variable. The associations between sleep quality and T/S were assessed using multivariable ordinary least squares regressions. All analyses were adjusted for demographics, lifestyle characteristics, psychosocial, and other factors. ResultsOverall, 16% reported never feeling well rested in the morning; 25.7% of respondents always had trouble waking during the night; and 12.8% always had trouble waking up too early in the morning. Respondents who never felt rested in the morning had significantly shorter TL than those who always felt rested in the morning (adjusted beta = -0.08, standard error = 0.03, P < .01). The composite sleep measure was not significantly associated with shorter TL. ConclusionsIn this cohort of older adults, not feeling well rested in the morning was significantly and inversely associated with TL; however, the composite measure of sleep quality was not significantly associated with TL. These findings suggest a potential connection between one of the measures of impaired sleep and reduction in TL, a marker of cellular aging that has been linked to multiple chronic conditions.

Association between telomere length and neighborhood characteristics by race and region in US midlife and older adults.

Disadvantaged neighborhoods are correlated with worse health outcomes, particularly among US Blacks. However, less is known about the link between neighborhood characteristics and biomarkers of cellular age, such as telomere length (TL), which may be implicated in racial health inequities. Moreover, this relationship may vary across US region given patterns of racial segregation across the US. Therefore, this study analyzed 2008 Health and Retirement Study data on 3,869 US-born white and Black adults >50 years old to examine race differences in the relationship between salivary TL and (1) neighborhood safety, cleanliness, and social cohesion and (2) interactions between neighborhood characteristics and US region. Neighborhood characteristics were not associated with TL in whites. However, significant associations were found among Blacks with variation by region. Blacks living in less clean neighborhoods in the Northeast (b=-0.03, SE=0.01, p<0.05), Midwest (b=-0.04, SE=0.01, p<0.01), and South (b=-0.05, SE=0.01, p<0.01) as well as those reporting less neighborhood safety and social cohesion in the Midwest (b=-0.03, SE=0.02, p<0.05 and b=-0.03, SE=0.01, p<0.05) and South (b=-0.03, SE=0.01, p<0.05 for both characteristics) had shorter TL than Blacks in the West. Therefore, exposure to neighborhood level historical discrimination and neglect may be detrimental to TL in Blacks. Future research should further examine how neighborhoods contribute to aging disparities.

Does salivary telomere length explain race/ethnic differences in aging?

ABSTRACT Telomere length (TL) is a biomarker that can be used to characterize variability in aging and may explain race/ethnic differences in aging. Yet, it remains unclear if TL is related to aging-associated health risks in multi-ethnic populations or if it explains race/ethnic differences in health. We examine whether salivary TL (STL) explains any of the race/ethnic variability in 15 indicators of high-risk biological, physical, and cognitive health among 4,074 White, Black, and Latinx older adults ages 54+ in the 2008 Health and Retirement Study. TL was assayed from saliva using quantitative PCR (T/S ratio). Decomposition analyses from logistic regression models show variation in STL does not account for any of the observed race/ethnic differences health. In age-adjusted, race-stratified models, STL was associated with HDL, total cholesterol, and lung function among Whites, but was not associated with any markers of health among Black or Latinx groups. In this diverse national sample of older adults, STL does not account for race/ethnic differences in late life health, is associated with relatively few indicators of health among Whites, and is not associated with indicators of health among Black or Latinx groups. STL may not be a useful biomarker for understanding racial/ethnic differences in population aging among older adults.

Sex differences in the association between salivary telomere length and multimorbidity within the US Health & Retirement Study.

BackgroundTelomere length is associated with several physical and mental health conditions, but whether it is a marker of multimorbidity is unclear. We investigated associations between telomere length and multimorbidity by sex.MethodsData from adults (N = 5,495) aged ≥50 years were taken from the US Health and Retirement Study (2008–14). Telomere length was measured in 2008 from salivary samples. The cross-sectional associations between telomere length and eight chronic health conditions were explored using logistic regression, adjusting for confounders and stratified by sex. Logistic, ordinal and multinomial regression models were calculated to explore relationships between telomere length and multimorbidity (using a binary variable and a sum of the number of health conditions) and the type of multimorbidity (no multimorbidity, physical multimorbidity, or multimorbidity including psychiatric problems). Using multilevel logistic regression, prospective relationships between telomere length and incident multimorbidity were also explored.ResultsIn cross-sectional analyses, longer telomeres were associated with reduced likelihood of lung disease and psychiatric problems among men, but not women. Longer telomeres were associated with lower risk of multimorbidity that included psychiatric problems among men (OR=0.521, 95% CI: 0.284 to 0.957), but not women (OR=1.188, 95% CI: 0.771 to 1.831). Prospective analyses suggested little association between telomere length and the onset of multimorbidity in men (OR=1.378, 95% CI: 0.931 to 2.038) nor women (OR=1.224, 95% CI: 0.825 to 1.815).ConclusionsAlthough telomere length does not appear to be a biomarker of overall multimorbidity, further exploration of the relationships is merited particularly for multimorbidity including psychiatric conditions among men.

Maternal stress and social support prospectively predict infant inflammation

Maternal stress has been suggested to be a risk factor for offspring health, while social support has been shown to be a protective factor for offspring functioning. Currently, research has yet to investigate how both of these factors may relate to infant inflammatory processes and associated biological aging in the first years of life. In 48 mother-infant dyads, we investigated whether maternal parenting stress and social support when infants were 12 and 18 months of age were cross-sectionally associated with infant salivary C-reactive protein (sCRP) during these times. In addition, we investigated whether parenting stress and social support were prospectively associated with later sCRP and changes in sCRP from 12 to 18 months of age, as well as whether those changes in sCRP were associated with subsequent infant salivary telomere length (sTL), a marker of biological aging. Analyses revealed that while there were no cross-sectional associations between maternal factors and infant sCRP, maternal parenting stress and social support when infants were 12 months of age predicted infant sCRP at 18 months of age. Further, maternal social support predicted changes in infant sCRP from 12 to 18 months of age. We observed a null association between infant sCRP and sTL. Implications for the ways that maternal mental health and social support may impact biological mechanisms related to disease processes in infants are discussed.

Stress and Salivary Telomere Length in the Second Half of Life: A Comparison of Life-course Models.

Previous research has explored the relationship between childhood and adulthood stressful life events (SLEs) and adult salivary telomere length (TL), but no research to date has tested different life-course models in which stress in adulthood may fully, partly, or not mediate the relationship between childhood stress and adult TL. To fill this gap, we elaborate over previous work by Puterman et al. (2016) and other standard models that do not account for the temporal order of stressors in childhood and adulthood, by using structural equation modeling (SEM) for a sample of 5,754 Health and Retirement Study (HRS) participants to compare the fit of three nested life-course models-social trajectory, early critical period, and cumulative risk. Results indicated that the social trajectory model, in which the association between childhood SLEs and TL in later adulthood is fully mediated by adulthood SLEs, fit the data better than the early critical period (no mediation) and cumulative risk (partial mediation) models. In the social trajectory model, childhood SLEs are related to TL in later life only through adulthood SLEs. The direct physiological effect of childhood SLEs on TL in later life would be overestimated if adulthood SLEs are overlooked.

Relational Victimization and Telomere Length in Adolescent Girls.

An emerging body of research suggests that telomere length (TL)-a measure of cellular aging-is inversely associated with experiences of childhood stress. Given the salience of peer relationships in childhood and adolescence, we tested whether relational victimization is a unique and specific predictor of salivary TL in girls. Results examining 122 girls (ages 9-15) revealed that greater relational victimization was related to shorter TL but that similar associations were not evident for other measures of social relationships nor accounted for by factors related to depression, life stress, or 5-HTTLPR genotype. The present findings suggest that relational victimization is uniquely associated with TL in adolescence, revealing a link between key aspects of social relationships and biological processes.

Validation of Minimally-Invasive Sample Collection Methods for Measurement of Telomere Length.

Objective: The discovery of telomere length (TL) as a biomarker of cellular aging and correlate of age-related disease has generated a new field of research in the biology of healthy aging. Although the most common method of sample collection for TL is venous blood draw, less-invasive DNA collection methods are becoming more widely used. However, how TL relates across tissues derived from these sample collection methods is poorly understood. The current study is the first to characterize the associations in TL across three sample collection methods: venous whole blood, finger prick dried blood spot and saliva.Methods: TL was measured in 24 healthy young adults using three modes of sample collection for each participant: venous whole blood, finger prick dried blood spot and saliva. Relative TL was measured using quantitative polymerase chain reaction.Results: TL in finger prick dried blood spots (DBS) washighly correlated with TL in whole blood (r = 0.84, p < 0.001). Salivary TL was also correlated with whole blood TL (r = 0.56, p = 0.005), but this association was not as strong as that of dried blood spot TL (Steiger’s Z = 2.12, p = 0.034). TL was longer in saliva than in whole blood or DBS (p’s < 0.001).Conclusions: These findings have important implications for future study design by supporting the validity of less-invasive methods that can be implemented with vulnerable populations or in the field. Further, these findings aid in interpreting the burgeoning area of biological aging research and may shed light on our understanding of inconsistencies in the empirical literature.

Infant HPA axis as a potential mechanism linking maternal mental health and infant telomere length

Maternal depression has been suggested to be an independent risk factor for both dysregulated hypothalamic-pituitary-adrenal axis (HPA) functioning and shorter telomere length in offspring. In contrast, research suggests that individual differences in mindfulness may act as a protective factor against one’s own telomere degradation. Currently, research has yet to investigate the association between longitudinal changes in maternal mental health (depressive symptoms and mindfulness) and salivary infant telomere length, and whether such changes might be mediated by alterations in infant cortisol response. In 48 mother-infant dyads, we investigated whether the changes in maternal mental health, when infants were 6–12 months of age, predicted change in infant cortisol reactivity and recovery over this period. We also investigated whether these changes in infant HPA functioning predicted subsequent infant salivary telomere length at 18 months of age. Furthermore, we investigated whether change in infant HPA functioning provided a potential pathway between changes in maternal mental health factors and infant salivary telomere length. Analyses revealed that increases in maternal depressive symptoms over that six-month period indirectly related to subsequent shorter infant telomere length through increased infant cortisol reactivity. Implications for the ways in which maternal mental health can impact offspring stress mechanisms related to aging and disease trajectories are discussed.

Father Loss and Child Telomere Length.

Father loss during childhood has negative health and behavioral consequences, but the biological consequences are unknown. Our goal was to examine how father loss (because of separation and/or divorce, death, or incarceration) is associated with cellular function as estimated by telomere length. Data come from the 9-year follow-up of the Fragile Families and Child Wellbeing Study, a birth cohort study of children in 20 large American cities (N = 2420). Principal measures are as follows: salivary telomere length (sTL), mother reports of father loss, and polymorphisms in genes related to serotonergic and dopaminergic signaling. At 9 years of age, children with father loss have significantly shorter telomeres (14% reduction). Paternal death has the largest association (16%), followed by incarceration (10%), and separation and/or divorce (6%). Changes in income partially mediate these associations (95% mediation for separation and/or divorce, 30% for incarceration, and 25% for death). Effects are 40% greater for boys and 90% greater for children with the most reactive alleles of the serotonin transporter genes when compared with those with the least reactive alleles. No differences were found by age at father loss or a child's race/ethnicity. Father loss has a significant association with children's sTL, with the death of a father showing the largest effect. Income loss explains most of the association between child sTL and separation and/or divorce but much less of the association with incarceration or death. This underscores the important role of fathers in the care and development of children and supplements evidence of the strong negative effects of parental incarceration.