Novel studies on a "silent" high affinity mutant hemoglobin (San Diego, beta 109 Val replaced by Met)

Secondary erythrocytosis due to hemoglobin San Diego

High-oxygen-affinity hemoglobin variants are a rare clinical entity that can present with secondary erythrocytosis. Herein, the author reports a case of a 41-year-old man with a 4-year history of secondary erythrocytosis of unknown etiology. Physical examination was unremarkable except for plethora of the palms. Myeloproliferative neoplasms and common causes of secondary erythrocytosis were ruled out. The P50 oxygen-hemoglobin dissociation curve was left shifted. Hemoglobin electrophoresis was silent; however, globin mass spectrometry revealed a β-globin variant. Globin sequencing confirmed hemoglobin San Diego. This case highlights the fact that rare high-oxygen-affinity variants should be considered in the differential diagnoses of secondary erythrocytosis.

Hemoglobin San Diego/beta zero thalassemia in a Greek adult

Interaction of beta zero thalassemia with Hb San Diego [a high affinity hemoglobin variant, alpha 2 beta (2)109(G11)Val----Met] in a 29-year-old Greek male is described. A marked polycythemia with low MCH and MCV, but minor clinical problems were observed. Functional properties of the isolated variant are described.