In contrast to the acquired MPDs, mutations of the erythropoietin receptor and thrombopoietin receptor have been identified in familial forms of nonclonal erythrocytosis and thrombocytosis, respectively.
The new EPOR gene mutation 5881G>T was found to segregate with isolated erythrocytosis in the affected family and this mutation represents the most extensive EpoR truncation reported to date, associated with familial erythrocytosis.