EPAS1 and polycythemia: Furthermore, several amino acid substitutions c.1601C>G (p.Pro534Arg), c.1601C>T (p.Pro534Leu), c.1603A>G (p.Met535Val), c.1603A>T (p.Met535Leu), c.1604T>C (p.Met535Thr), c.1615G>A (p.Asp539Asn), c.1620C>A (p.Phe540Leu), and c.1631C>G (p.Pro544Arg) in the immediate vicinity of the identified variant have been reported in patients with erythrocytosis as pathogenic (Bento, 2018; Kristan et al., 2019), suggesting the critical importance of the identified region for the function of EPAS1 protein and severe effect on patient’s phenotype (Anzej Doma et al., 2021b).