The Imerslund-Gräsbeck syndrome is a rare hereditary autosomal recessive disease characterized by the onset of megaloblastic anemia and asymptomatic proteinuria during the first 2 years of life.

To emphasize the importance of early detection of this disorder, because of its high morbidity when not correctly treated, and of screening and genetic counseling of the asymptomatic family members.

The authors report two patients, a boy and a girl, 8 and 10 years old, respectively. Their history revealed anemia and multiple blood transfusions since infancy. They evolved with pancytopenia during childhood, and diagnosis of severe aplastic anemia or Fanconi Syndrome was suspected. They were referred to the Bone Marrow Transplantation Department at Hospital das Clínicas, Universidade Federal do Paraná, Brazil.

Laboratory investigations revealed pancytopenia in peripheral blood. Bone marrow aspiration showed a marked megaloblastic erythropoiesis. Twenty-four-hour urine collection revealed proteinuria (3.0 and 5.8 g/dl, respectively). Cytogenetic analysis was normal. Resolution of symptoms followed replacement therapy with parenteral vitamin B12.

The presence of megaloblastic anemia in children should be followed by investigation of proteinuria for the identification of this disorder. This syndrome is a rare but easily diagnosed, and can be effectively treated.