a Copy number alterations (CNA) in cases with stable disease versus cases showing progression to myelofibrosis. Log2 copy ratios for individual CpG sites as well as segments were calculated from the median signal intensity of samples with fibrotic progression compared to samples with stable disease as reference set. The x-axis visualizes genomic locations with centromere positions indicated by dashed lines, whereas the y-axis indicates individual log2 copy ratios. No gains or losses of segments (absolute log2 copy ratio ≥ 0.5) could be detected between both sample sets. b Results of the mutation analysis. The cases showing progress to myelofibrosis are represented in the upper part of the figure, the cases with stable disease in the lower part. Each red square indicates the presence of a mutation causing a loss of function or an altered protein function. The asterisk on the right side (*) mark the three samples which failed the initial QC procedure, but were classified correctly using the linear discriminant classifier (see Additional file 1: Figure S1). Since the case series of this study is a subset of the series described in detail before by us the results of the mutation profiling are also contained within Fig. 2 of Bartels et al.