A patient who is heterozygous for hemoglobins S and Oarab may have a clinical syndrome similar to homozygous hemoglobin S (hemoglobin SS).


Clinical features:

(1) The onset of clinical symptoms is often during infancy or childhood.

(2) The patient may experience sickling-related disorders similar to those seen in sickle cell disease with pain crises, hemolytic anemia, vaso-occlusive crises and infection.

(3) The peripheral blood smear may show sickled erythrocytes.


Hemoglobin findings:

(1) Hemoglobin Oarab comigrates with hemoglobin A2 and hemoglobin C in acetate electrophoresis. A patient may be misdiagnosed as hemoglobin SC if only limited testing is performed.

(2) Hemoglobin Oarab can be distinguished from hemoglobin C in citrate agar electrophoresis or isolectric focusing.

(3) Hemoglobin Oarab can be separated from other hemoglobins using HPLC.

(4) Confirmation of Oarab can be done by sequencing beta-globulin.


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