Analysis of single colonies for mutations in TET2 and JAK2. Mononuclear cells from peripheral blood were grown in methylcellulose. Single burst forming units erythroid (BFU-E) were picked and analyzed individually for the presence of TET2 and JAK2-V617F mutations by DNA sequencing and allele-specific polymerase chain reaction, respectively. Each colony is represented by a dot that is placed into one of 6 quadrangles representing the 6 possible genotypes: wild-type (wt), heterozygous (het) and homozygous (hom) for JAK2-V617F on the vertical axis, and for TET2 mutations on the horizontal axis. The unique patient numbers, the diagnoses (PMF indicates primary myelofibrosis; ET, essential thrombocythemia; and PV, polycythemia vera) and the allelic ratio of JAK2-V617F in purified granulocytes (%T) are shown above the corresponding boxes. Light blues arrows indicate the suggested order of mutation events. (A) Patterns from patients with homozygous colonies at the first time point, which did not expand. (B) Patterns compatible with a biclonal state of the disease with a gradual decrease in JAK2-V617F allelic burden.