Huang et al described the case of a 14-year-old girl diagnosed with ITP followed by ET 3 years later.[7] Sobas et al reported on a 45-year-old woman initially diagnosed with ITP who developed ET 21 years later.[8] A recent report from Caocci et al described the case of a 72-year-old woman diagnosed with ITP who developed ET 13 years later.[9] The patients in all these 3 cases were positive for the JAK2 V617F mutation, which was also present in the case of ET with subsequent ITP development described in this report. The gene discussed is JAK2; the disease is essential thrombocythemia.