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Effects of Preanalytical Factors on the Molecular Size of Cell-Free DNA in Blood

¹ Department of Chemical Pathology and² Accident and Emergency Medicine Academic Unit, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong Special Administrative Region, China

^aaddress correspondence to this author at: Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong Special Administrative Region, China; fax 852-2194-6171, e-mail loym@cuhk.edu.hk

The first 300 words of the full text of this article appear below.

Recently, plasma DNA analysis has been increasingly explored for different clinical diagnostic purposes. Previous studies have shown that the concentration of plasma DNA is increased in patients with neoplastic diseases (1), pregnancy-related complications (2)(3), trauma(4), and certain autoimmune diseases (5). In addition to quantitative analysis, qualitative changes in plasma DNA have also been investigated in different physiologic and pathologic conditions. In this regard, our group has shown that fetal DNA is shorter than the maternal counterpart in the plasma of pregnant women (6), and this has allowed the enrichment of fetal DNA from maternal plasma by size fractionation (7). It has also been shown that plasma DNA fragments are longer in patients suffering from a variety of neoplastic diseases (8). In addition, circulating Epstein–Barr virus DNA molecules in patients with nasopharyngeal carcinoma have been found to consist mainly of short DNA fragments <180 bp in size (9). Because the samples collected from patients and healthy controls in these studies were usually collected at different time points and under different conditions, it is important to ensure that the observed variations in the sizes of plasma DNA are the result of biological changes rather than artifacts attributable to differences in sample handling. Therefore, in this study, we investigated the effects of several preanalytical factors, including clotting, delayed separation of blood cells from plasma, freezing–thawing, and storage, on the integrity of circulating cell-free DNA.

We recruited 27 healthy volunteers for modules 1 to 4 of the study. Venous blood (30 mL) was collected from each volunteer into eight tubes containing EDTA and one plain tube. The samples serving as references were processed immediately after collection. Plasma was separated from the blood cells by centrifugation at . . . [Full Text of this Article]

Module 1.

Module 2.

Module 3.

Module 4.

Module 5.

The following articles in journals at HighWire Press have cited this article:

				K.C. A. Chan, S. F. Leung, S. W. Yeung, A. T.C. Chan, and Y.M. D. Lo Quantitative Analysis of the Transrenal Excretion of Circulating EBV DNA in Nasopharyngeal Carcinoma Patients Clin. Cancer Res., August 1, 2008; 14(15): 4809 - 4813. [Abstract] [Full Text] [PDF]

				M. L. Gulley and W. Tang Laboratory Assays for Epstein-Barr Virus-Related Disease J. Mol. Diagn., July 1, 2008; 10(4): 279 - 292. [Abstract] [Full Text] [PDF]

				K.C. A. Chan, S.-F. Leung, S.-W. Yeung, A. T.C. Chan, and Y.M. D. Lo Persistent Aberrations in Circulating DNA Integrity after Radiotherapy Are Associated with Poor Prognosis in Nasopharyngeal Carcinoma Patients Clin. Cancer Res., July 1, 2008; 14(13): 4141 - 4145. [Abstract] [Full Text] [PDF]