Analytical Validation of Relative Average Telomere Length Measurement in a Clinical Laboratory Environment

Abstract

Background Average telomere length in whole blood has become a biomarker of aging, disease, and mortality risk across a broad range of clinical conditions. The most common method of telomere length measurement for large patient sample sets is based on quantitative PCR (qPCR). For laboratory-developed tests to be performed on clinical samples, they must undergo a rigorous analytical validation, currently regulated under CLIA. Methods Whole blood samples from 40 donors were used in the analytical validation of methods for relative average telomere length (rATL) measurement. Three technical replicate DNA samples were extracted from each whole blood sample and placed in three independent wells on a sample plate. Each of these sample plates was assayed 12 times during the validation process. The study was conducted over a 20-day period, once in the morning and once in the evening, using 3 different operators. Results Our process of rATL measurement beginning with DNA extraction followed by qPCR-based assay resulted in repeatability and reproducibility CV of <5% and amplification efficiencies near 100%. The validated assay was used to establish a reference interval derived from 2 cohorts of individuals: (a) San Francisco Bay area (n = 504) and (b) a US cross-sectional, demographic population (n = 357). Conclusions We present advances in the establishment of a highly reproducible analytically validated process for determining rATLs in a CLIA laboratory environment.

Genetic and clinical determinants of telomere length

“…All LTL experiments were conducted at Marshfield Clinic Research Institute using a modified qPCR technique as described in Blauwkamp et al. 30 This technique expresses LTL as a ratio of telomere repeat number relative to a single copy gene (i.e., RNAseP). All LTL assays were run in quadruplicate and standardized by quantifying against a standard curve present on each assay plate.…”