Laboratory recognition of a rare hemoglobinopathy: hemoglobins SS and SG(Philadelphia) associated with alpha-thalassemia-2.

This article describes the laboratory investigation of an unusual hemoglobinopathy involving hemoglobin (Hb) S, HbSG(Philadelphia), and alpha-thalassemia-2 in a patient whose phenotype was HbSC by alkaline electrophoresis. Findings of a mean corpuscular volume of 62 fL and microcytes on the blood smear were inconsistent with HbSC disease. The patient's clinical course over several years had been mildly symptomatic. Testing in our hospital laboratory using isoelectric focusing and cation-exchange high-performance liquid chromatography to separate hemoglobins showed an unknown variant. Additional studies, including globin chain electrophoresis, reverse-phase high-performance liquid chromatography, and polymerase chain reaction-based DNA analysis were performed at reference laboratories, which reported the following findings: HbG(Philadelphia) associated with alpha-thalassemia-2, HbS and HbG(Philadelphia), and the alpha-globin deletions defining the -alpha3.7/-alpha3.7 genotype. The hemoglobin molecular defects, alpha-thalassemia-2, and the pattern of inheritance are discussed.

Analytical evaluation of methods for serum creatine kinase-MB. Electrophoresis, immunoinhibition and solid phase separation.

The purpose of this study was to evaluate immunoassay methods for the measurement of serum cardiac creatine kinase isoenzyme (CK-MB) with respect to sensitivity and specificity. The CK-MB electrophoretic assay (Helena Laboratories) was used as the reference. Two principles of immunoassay were included in the evaluation,--immunoinhibition and solid phase separation. The direct immunoinhibition techniques were from Beckman Instruments (CKMB reagent) and DuPont Medical Products (CKMB). Three solid phase separation techniques were from Abbott Laboratories (IMx CKMB), DuPont (acaPlus MCKMB), and Tosoh Medics Inc. (AIA-Pack CKMB). The electrophoretic method for separation of the CK isoenzymes has good specificity but lacks sensitivity for CK-MB in low concentrations. The immunoinhibition methods lack specificity and correlate poorly with the electrophoresis method and with the solid phase methods. The solid phase separation techniques are highly sensitive and show an excellent correlation with electrophoresis when based on specificity. The solid phase separation methods correlate well with each other.