Setting the Trajectory: Racial Disparities in Newborn Telomere Length

Telomeres normally shorten with age in somatic tissues and, in general, telomere length (TL) generally is correlated between different tissues, particularly in youth1-3 Aging and multiple other factors influence TL, including oxidative stress, DNA damage, DNA repair mechanisms, and genetic factors.4 TL also has been associated with both psychosocial stressors (exposure to violence, neighborhood disorder, racial discrimination), as well as chronic diseases (obesity, cardiovascular disease, diabetes).5-9 These diseases, associated with both early adversity and the aging process,10 have significantly higher rates in Blacks, particularly women, than in other races.11, 12 Racial differences in TL have been demonstrated in adults and adolescents,.13, 14 Baseline TL is longer in Blacks. TL attrition, an indicator of cellular aging predicted by initial TL, is also significantly greater in Blacks. This suggests that biological processes associated with aging may underlie persistent health disparities.6, 11, 13 Chae et al reported that racism was a significant predictor of shorter TL in Black adults, suggesting that not only do racial differences exist but that exposure to racism may contribute to part of the observed racial differences in TL.5 Thus, the determination of the earliest developmental time point at which racial differences in TL exist is salient.15 Shorter infant TL has been associated with a range of negative birth outcomes including preterm rupture of membranes, gestational diabetes, prenatal exposure to anti-retroviral therapy in HIV exposed infants, and maternal stressors during pregnancy.16-19 Studies have also demonstrated shorter placental TL of infants with intrauterine growth restriction (IUGR).20 Only one previous study, designed to examine cross tissue correlation of TL, presented any data on the association between race and TL at birth. 21 In this study, TL was not significantly different between Black and White infants. Although newborn TL was significantly associated with both maternal age and infant birth weight, analyses did not account for these associations or potential moderation of racial differences by gestational age or infant sex. Given consistent evidence of both sex differences in TL,22, 23 and racial differences in birth weight, these factors are likely critical covariates when examining racial differences in newborn TL. One study has demonstrated a significant correlation between TL from dried blood spots and whole blood obtained via venipuncture, suggesting that blood spot DNA is a practical alternative DNA source. 25 This study examined the feasibility of newborn blood spots as a source for newborn TL analyses, and explored racial differences in newborn TL in a prospective cohort of infants. Based on existing data in adults, we hypothesized that racial differences would be found, with Blacks having longer TL than Whites. Further, as our previous work and that of others has demonstrated sex differences, 7, 22, 23 we examined whether the sex of the infant moderated racial differences. The established evidence that the rate of TL attrition is proportional to baseline TL coupled with the increasing evidence linking TL to negative health outcomes, suggest that evaluation of racial differences in infant TL may provide novel insight into the early biological evidence of health disparities.