Telomere length (TL) has emerged as a promising replicative cellular aging marker that reflects both genetic and non-genetic influences. Quantitative PCR (qPCR) TL measurement has been favored as a cost-effective method that can be easily implemented, especially in population studies with limited quantities of source material. However, several recent reports have revealed inconsistencies in telomere length measurements when applying different DNA extraction methods to the same source material. In this study we tested three DNA extraction methods on saliva samples from 48 participants of the National Growth and Health Study (NGHS) collected with DNA Genotek’s Oragene kit. The chosen extraction kits represent three distinct approaches to genomic DNA extraction from lysed cells and we employed two different operators to carry out all assays on the same samples. We measured DNA yield and quality and calculated the between-operator agreement of qPCR TL measurements (intraclass correlation, ICC). Our analyses showed that while both QIAamp and Agencourt DNAdvance had higher agreement between the 2 operators (ICC=0.937, CI [0.891, 0.965] and ICC=0.95, CI [0.911, 0.972] respectively), compared to PrepIT kit (ICC=0.809, CI [0.678, 0.889]), QIAamp extracted DNA samples were notably degraded. Using generalizability theory, we found that the participant-by-extraction-method interaction explained about 10% of total variation in TL, suggesting that TL differences across methods are somewhat participant-specific. Therefore, our results suggest that the among the three DNA extraction methods tested, Agencourt (magnetic bead purification) is the preferred kit, and we also strongly recommend against combining different extraction methods within a study population.
Objective. The study objective was to compare leukocyte telomere length (LTL) among patients with systemic lupus erythematosus (SLE) diagnosed in childhood versus adulthood.Methods. Data are from the Black Women's Experiences Living with Lupus (BeWELL) study. Multivariable linear regression analyses that examined childhood diagnosis of SLE (diagnosed before 18 years of age), age, and their interaction in relationship to LTL were conducted, adjusting for a range of demographic, socioeconomic, and health-related covariates.Results. The total analytic sample size was 415. Forty participants (9.6%) were diagnosed in childhood. There was no main effect of childhood diagnosis on LTL (b = 0.007; 95% confidence interval [CI]: −0.089 to 0.103). However, the interaction between age and childhood diagnosis was significant (b = −0.008; 95% CI: −0.016 to −0.001), indicating a steeper inverse association between age and LTL among those diagnosed in childhood compared with those diagnosed in adulthood. This interaction remained statistically significant (P = 0.024) after controlling for disease duration measured dichotomously (less than 10 years vs. 10 years or more); it was marginally significant (P = 0.083) when controlling for disease duration measured continuously.Conclusion. This cross-sectional analysis suggests that Black women with childhood-onset SLE may undergo accelerated LTL shortening compared with their adult-onset counterparts. This relationship persisted even after controlling for differences in SLE damage and disease duration. These findings inform research on immunosenescence mechanisms of SLE.Participants were recruited from the Georgians Organized Against Lupus cohort, which was supported by the US Centers for Disease Control and Prevention under cooperative agreements U01DP005119 and U01DP006488.
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