Abstract
A 28βyearβold asymptomatic male of Iranian Jewish (Meshadi) heritage was found on routine exam to have an erythrocytosis (RBC = 6.22 Γ 10^12^/l, Hgb = 19.2 g/dl, Hct = 58.9%). Splenomegaly was absent on physical exam. There was no family history of erythrocytosis. His oxygen dissociation curve was leftβshifted with a __p__50 of 19 mmHg (normal = 25β32 mmHg). Hemoglobin electrophoresis showed no abnormalities. DNA sequencing of the hemoglobin Ξ² globin gene and both Ξ± globin genes did not reveal a mutation. A 2,3βbisphosphoglycerate (BPG) level was markedly decreased at 0.3 ΞΌmol/g Hb (normal = 11.4β19.4 ΞΌmol/g Hb). The patient's bisphosphoglycerate mutase (BPGM) enzyme activity was also markedly decreased at 0.16 IU/g Hb (normal = 4.13β5.43 IU/g Hb). A red cell enzyme panel revealed a markedly decreased Gβ6βPD level (0.3 U/g Hb, normal = 8.6β18.6 U/g Hb). His parents and a brother were also available for evaluation. Both parents showed normal 2,3βBPG levels but BPGM activity approximately 50% of normal. Paradoxically, the brother showed normal BPGM activity but a slightly decreased 2,3βBPG level. All family members had markedly decreased Gβ6βPD activity. DNA sequencing of the BPGM gene showed the propositus to be homozygous for 185 GβA, Arg 62 Gln in exon 2. Thus, the erythrocytosis in this patient is secondary to low 2,3βBPG levels, due to a deficiency in BPG mutase. This appears due to consanguinity within this family. Am. J. Hematol. 75:205β208, 2004. Β© 2004 WileyβLiss, Inc.