However, the frequency of CALR exon 9 mutations in our study is higher than that of Thai (Limsuwanachot et al., 2017), Korean (Kim et al., 2015) , Italian (Rotunno et al., 2014) , Polish (Wojtaszewska et al., 2015) , and Brazilian (Nunes et al., 2015) ET patients; in those populations the mutation rate of CALR exon 9 mutations ranged from 12.5% to 15.5%. This evidence concerns the gene CALR and essential thrombocythemia.