Altered Erythropoiesis and Increased Hemolysis in Hemoglobin M Akita (M Hyde Park 692 His → Tyr) Disease

Abstract

Hb M Akita disease is a cyanotic hemoglobinopathy found in Akita Prefecture, Japan. The abnormal hemoglobin was found to be the same as Hb M Hyde Park (692 His → Tyr) by chemical analysis in 1967. In this disease signs of accelerated hemolysis (serum bilirubin, 2.4 mg/dl; splenomegaly, 2 finger breadths; Hb, 10.7 g/dl; reticulocyte index, 2.7) were noted, but the causes of its slight anemia were revealed to be fairly complex by ferrokinetic study, RBC life-span measurement, and ^mTc myeloscintigram.

The anemia in this disease is caused not only by shortened erythrocyte survival (T 1/2 = 11.5 days by ⁵¹Cr-tagging method) and sequestration of red cells in the spleen (Spleen: liver ratio = 2.5 ∼ 3.0 by ⁵¹Cr-surface counting), hut also by slow supply of erythro-cytes to the peripheral blood from the bone marrow, presumably, related to the existence of unstable Hb M Akita and its derivative (Hb Akita) in the erythroid cells. Both Carrell's isopropanol test and Heinz body formation test were positive. In spite of maximally increased total erythropoiesis (8 times as high as the normal level; M:E ratio = 0.22:1.0), supply of red cells from the bone marrow to the peripheral blood was significantly decreased. The distribution of hemato-poietic sites throughout the body was reasonably uniform.