To test this hypothesis, we extracted genomic DNA from one peripheral blood and 25 bone marrow samples of AML patients with t(8;21) from the University Medical Centers Freiburg, Germany and Nijmegen, The Netherlands. All patients had provided ethic board approved informed consent. The blast count in the peripheral blood sample was 35% and in bone marrow samples 470% in the majority of samples (range: 25-90%). In addition, to explore the mutation status in a homogeneous blast population, we investigated two AML cell lines bearing t(8;21), Kasumi-1 and SKNO. We amplified a 268-bp fragment of AML1-ETO encompassing the entire coding region of the NHR4 domain (aa658-707) (Table 1, Figure 1) and applied bidirectional sequencing (GATC Biotech, Konstanz, Germany). However, we identified no mutations within the NHR4 coding genomic sequence of these AML patients or the two cell lines. With the limitations of a cohort of 26 patient samples, we conclude that mutations within the NHR4 domain of AML1-ETO are probably a very infrequent event in patients with t(8;21). Our results also support the idea that in vivo, other mechanisms than NHR4 mutations, for example, a dysfunctional SON protein might be a reason for hampered interaction of AML1-ETO and SON. Conflict of interestThe authors declare no conflict of interest. AcknowledgementsThis study was in part supported by a grant from the Deutsche Krebshilfe (108397 to BH). We thank Dong-Er Zhang, University of California, San Diego, USA for her very helpful comments with this study.

Essential hypertension (EH) is a chronic disease with clear epigenetic component. Inflammation and endothelial dysfunction have a great role in the development of persistent blood pressure elevation. The aim of this study was to explore an association between EH and DNA methylation in pro-inflammation cytokine gene interleukin-6 (IL-6) during the inflammatory process. We performed methylation analysis of peripheral blood DNA using bisulphite pyrosequencing technology between 96 EH patients and 96 age- and gender-matched healthy controls. The present results showed that three cytosine-phosphate-guanine (CpG) sites of IL-6 promoter CpG island had different lower methylation in EH group compared with controls, but only CpG2 (58.43±7.53 versus 62.34±9.65, P=0.004) and CpG3 (51.52±6.18 versus 57.45±8.29, P<0.001) had statistical difference. Logistic regression analysis found CpG3 hypomethylation was a risk factor of EH (odds ratio=1.111, adjusted P=0.004). In addition, we found hypermethylation of CpG1 (64.84±7.06 versus 61.84±8.61) and CpG2 (62.04±7.40 versus 59.30±9.57) in male compared with female. In male, we found hypomethylation of CpG2 (60.41±7.74 versus 64.28±6.36) and CpG3 (53.70±8.62 versus 57.78±7.87) of smoker versus non-smoker and hypomethylation of CpG2 (60.89±7.32 versus 64.70±7.03) and CpG3 (53.23±7.99 versus 60.48±7.58) of drinker versus non-drinker. Furthermore, the CpG2 and CpG3 had a negative correlation with systolic blood pressure and diastolic blood pressure (P<0.05). Receiver operating characteristic curve analysis showed that CpG2 (area under curve: 0.638, P=0.001) and CpG3 (area under curve: 0.704, P<0.001) had a diagnostic value to predict the risk of EH. In summary, our study revealed hypomethylation of IL-6 was correlated with the risk of EH in the population assessed and we found the differences of IL-6 promoter methylation in gender, smoking and drinking.

clinician to detect possible relapse in patients if TK1 levels start to increase.A minor limitation of measuring serum TK1 activity is the substantial variance between patients. This variation between individuals prevents direct comparison between patients. For this reason, we presented the changes in serum TK1 activity for the ALL and AML patients as a percentage of the maximum measured for each individual (Figures 3 and 4). Our results show that the changes in serum TK1 activity are only useful for prognosis when compared with the individual's previous samples. Therefore, a baseline level of serum TK1 activity must be established for each individual if serum TK1 is to be used as a prognostic tool in leukemia, similar to the method currently used in monitoring prostate-specific antigen in men. Variations in TK1 levels between serial samples from the same individual are directly reflective of the response to treatment, indicating that TK1 measurements can accurately predict patient prognosis.Our results comparing the mean serum TK1 levels of ALL patients with healthy individuals indicated statistically significant differences between the two groups. This confirms the reality of measuring serum TK1 levels as a diagnostic tool. Statistical significance between serum TK1 levels in ALL patients of different stages confirms TK1 as a possible prognostic tool.This study also indicates that the immunoassay, utilizing the TK1-specific mAb, is an accurate method of measuring serum TK1 levels. The development of an immunoassay to measure serum TK1 levels would be more practical and efficient for use in a clinical setting. Through continued investigation of TK1, we hope to provide clinicians with a valuable tool for earlier detection and improved evaluation of treatment success. AcknowledgementsWe thank KEM Baillie and JM Bridges for providing the serial blood samples from the ALL and AML patients. We also thank the Biological Carcinogenesis Branch for providing blood samples.