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Validating quantitative PCR assays for cfDNA detection without DNA extraction in exercising SLE patients

2021; Nature Portfolio; Volume: 11; Issue: 1 Linguagem: Inglês

10.1038/s41598-021-92826-4

2045-2322

Elmo Neuberger, Alexandra Brahmer, Tobias Ehlert, Katrin Kluge, Keito F A Philippi, Simone Cosima Boedecker-Lips, Julia Weinmann‐Menke, Perikles Simon,

Lymphoma Diagnosis and Treatment

Abstract Circulating cell-free DNA (cfDNA) has been investigated as a screening tool for many diseases. To avoid expensive and time-consuming DNA isolation, direct quantification PCR assays can be established. However, rigorous validation is required to provide reliable data in the clinical and non-clinical context. Considering the International Organization for Standardization, as well as bioanalytical method validation guidelines, we provide a comprehensive procedure to validate assays for cfDNA quantification from blood plasma without DNA isolation. A 90 and 222 bp assay was validated to study the kinetics of cfDNA after exercise in patients with systemic lupus erythematosus (SLE). The assays showed ultra-low limit of quantification (LOQ) with 0.47 and 0.69 ng/ml, repeatability ≤ 11.6% (95% CI 8.1–20.3), and intermediate precision ≤ 12.1% (95% CI 9.2–17.7). Incurred sample reanalysis confirmed the precision of the procedure. The additional consideration of pre-analytical factors shows that centrifugation speed and temperature do not change cfDNA concentrations. In SLE patients cfDNA increases ~ twofold after a walking exercise, normalizing after 60 min of rest. The established assays allow reliable and cost-efficient quantification of cfDNA in minute amounts of plasma in the clinical setting. Additionally, the assay can be used as a tool to determine the impact of pre-analytical factors and validate cfDNA quantity and quality of isolated samples.