Two Cases of Familial Erythrocytosis With Increased Erythropoietin Activity in Plasma and Urine

Two brothers with familial erythrocytosis born to parents of a consanguinous marriage are described. Two other siblings were unaffected. There was a marked increase in erythropoietin concentration in both the plasma and urine, suggesting that a congenital defect led to erythropoietindependent polycythemia. Other causes of polycythemia were excluded.