Lam W K Jacky, Gai Wanxia, Sun Kun, Wong Raymond S M, Chan Rebecca W Y, Jiang Peiyong, Chan Natalie P H, Hui Winnie W I, Chan Anthony W H, Szeto Cheuk-Chun, Ng Siew C, Law Man-Fai, Chan K C Allen, Chiu Rossa W K, Lo Y M Dennis
Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China.
Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China.
Clin Chem. 2017 Oct;63(10):1614-1623. doi: 10.1373/clinchem.2017.272401. Epub 2017 Aug 7.
There is much interest in the tissue of origin of circulating DNA in plasma. Data generated using DNA methylation markers have suggested that hematopoietic cells of white cell lineages are important contributors to the circulating DNA pool. However, it is not known whether cells of the erythroid lineage would also release DNA into the plasma.
Using high-resolution methylation profiles of erythroblasts and other tissue types, 3 genomic loci were found to be hypomethylated in erythroblasts but hypermethylated in other cell types. We developed digital PCR assays for measuring erythroid DNA using the differentially methylated region for each locus.
Based on the methylation marker in the ferrochelatase gene, erythroid DNA represented a median of 30.1% of the plasma DNA of healthy subjects. In subjects with anemia of different etiologies, quantitative analysis of circulating erythroid DNA could reflect the erythropoietic activity in the bone marrow. For patients with reduced erythropoietic activity, as exemplified by aplastic anemia, the percentage of circulating erythroid DNA was decreased. For patients with increased but ineffective erythropoiesis, as exemplified by β-thalassemia major, the percentage was increased. In addition, the plasma concentration of erythroid DNA was found to correlate with treatment response in aplastic anemia and iron deficiency anemia. Plasma DNA analysis using digital PCR assays targeting the other 2 differentially methylated regions showed similar findings.
Erythroid DNA is a hitherto unrecognized major component of the circulating DNA pool and is a noninvasive biomarker for differential diagnosis and monitoring of anemia.
血浆中循环DNA的组织来源备受关注。使用DNA甲基化标记生成的数据表明，白细胞谱系的造血细胞是循环DNA池的重要贡献者。然而，尚不清楚红系谱系的细胞是否也会将DNA释放到血浆中。
利用成红细胞和其他组织类型的高分辨率甲基化图谱，发现3个基因组位点在成红细胞中低甲基化，但在其他细胞类型中高甲基化。我们开发了数字PCR检测方法，利用每个位点的差异甲基化区域来测量红系DNA。
基于亚铁螯合酶基因中的甲基化标记，红系DNA在健康受试者血浆DNA中所占比例的中位数为30.1%。在不同病因的贫血患者中，循环红系DNA的定量分析可以反映骨髓中的红细胞生成活性。对于红细胞生成活性降低的患者，如再生障碍性贫血患者，循环红系DNA的百分比降低。对于红细胞生成增加但无效的患者，如重型β地中海贫血患者，该百分比增加。此外，还发现红系DNA的血浆浓度与再生障碍性贫血和缺铁性贫血的治疗反应相关。使用针对其他2个差异甲基化区域的数字PCR检测方法进行血浆DNA分析也得到了类似的结果。
红系DNA是循环DNA池中迄今未被认识的主要成分，是用于贫血鉴别诊断和监测的非侵入性生物标志物。
