Telomeres are ribonucleoprotein structures at the end of all eukaryotic chromosomes that protect DNA from damage and preserve chromosome stability. Telomere length (TL) has been associated with various exposures, biological processes, and health outcomes. This article describes the monochrome multiplex quantitative polymerase chain reaction (MMqPCR) assay protocol routinely conducted in our laboratory for measuring relative mean TL from human DNA. There are several different PCR-based TL measurement methods, but the specific protocol for the MMqPCR method presented in this publication is repeatable, efficient, cost-effective, and suitable for population-based studies. This detailed protocol outlines all information necessary for investigators to establish this assay in their laboratory. In addition, this protocol provides specific steps to increase the reproducibility of TL measurement by this assay, defined by the intraclass correlation coefficient (ICC) across repeated measurements of the same sample. The ICC is a critical factor in evaluating expected power for a specific study population; as such, reporting cohort-specific ICCs for any TL assay is a necessary step to enhance the overall rigor of population-based studies of TL. Example results utilizing DNA samples extracted from peripheral blood mononuclear cells demonstrate the feasibility of generating highly repeatable TL data using this MMqPCR protocol.
Telomeres are ribonucleoprotein structures at the end of all eukaryotic chromosomes that protect DNA from damage and preserve chromosome stability. Telomere length (TL) has been associated with various exposures, biological processes, and health outcomes. This article describes the monochrome multiplex quantitative polymerase chain reaction (MMqPCR) assay protocol routinely conducted in our laboratory for measuring relative mean TL from human DNA. There are several different PCR-based TL measurement methods, but the specific protocol for the MMqPCR method presented in this publication is repeatable, efficient, cost-effective, and suitable for population-based studies. This detailed protocol outlines all information necessary for investigators to establish this assay in their laboratory. In addition, this protocol provides specific steps to increase the reproducibility of TL measurement by this assay, defined by the intraclass correlation coefficient (ICC) across repeated measurements of the same sample. The ICC is a critical factor in evaluating expected power for a specific study population; as such, reporting cohort-specific ICCs for any TL assay is a necessary step to enhance the overall rigor of population-based studies of TL. Example results utilizing DNA samples extracted from peripheral blood mononuclear cells demonstrate the feasibility of generating highly repeatable TL data using this MMqPCR protocol.
Access to efficient, culturally relevant, and validated measures of neurodevelopment in Low- and Middle-Income Countries (LMICs) remains a critical need. This study describes the validation and reliability of the Child Development Review (CDR), a parent report neurodevelopmental screening tool, for use in a cohort of Surinamese children aged 2–4 years. Complete data from 355 Surinamese children through the Caribbean Consortium for Research in Environmental and Occupational Health were utilized for validation. Convergent validity was assessed using a subset of 31 children with concurrently administered CDRs and Bayley Scales of Infant and Child Development Third Edition (BSID-III). Cronbach's alpha was used to assess subscale reliability. Cluster analyses were used to assess internal factor structure. Measures of convergent validity used Cohen's Kappa statistic and partial correlations between comparative CDR and BSID-III subscales. Cronbach's Alpha values were acceptable for all CDR subscales (range 0.63 - 0.79). CDR subscale responses clustered into two distinct groups, representing milestones that were or were not achieved. Patterns of change indicate increased milestone achievement with increased age. Partial correlations indicated that the social, fine motor, and language subscales of the CDR and BSID-III subscales were significantly correlated. However, Cohen's Kappa was only significant for the gross motor CDR and BSID-III subscales. The CDR has acceptable reliability, internal validity, and convergent validity. Use of the CDR should be considered as a screening tool for neurodevelopment in Suriname and may provide an efficient initial assessment of developmental delay in LMIC.
