Ten years after the initial erythrocytosis diagnosis, the NGS panel was conducted and showed two different heterozygous variants in the JAK2 gene c.1711G>A p.(Gly571Ser), and in the EPAS1 gene, c.466G>T, p.(Gly156Trp). The JAK2 variant is rare with a gnomAD minor allele frequency of 0.000471 (ACMG criterion PM2). This evidence concerns the gene JAK2 and polycythemia.