Evaluation of an automated capillary electrophoresis system in the screening for hemoglobinopathies

The biochemical diagnosis of hemoglobinopathies (thalassemias and hemoglobin (Hb) variants) is based on the separation and the quantification of Hb fractions. HPLC is the most commonly used method but capillary electrophoresis (CE) methods have also been developed successfully. The Capillarys II system is the first fully automated CE system that allows the quantification of Hb A2 and Hb F and the separation of Hb variants. We evaluated the ability of this system to separate and identify Hb variants and to quantify Hb A2 and Hb F.

The separation of 18 different Hb variants was studied and the imprecision on migration times was calculated for the three most frequent ones. The total imprecision on Hb A2 and Hb F quantification was determined. The results obtained for 44 patients were compared with those given by HPLC. The interference on Hb A2 measurement due to the presence of Hb S was studied.

Fourteen out of the 18 variants tested, including all variants of clinical importance, were separated from Hb A. Imprecision on migration times was less than 1%. For Hb A2 quantification, imprecision was less than 3.5% and for Hb F, less than 7.0%. The comparison with HPLC showed an acceptable agreement between both methods but a systematic negative bias for Hb A2 and both proportional and systematic biases for Hb F. No interference from the presence of Hb S on the quantification of Hb A2 was observed.

The fully automated Capillarys Hemoglobin method allows the detection and the separation of the most common Hb variants. It provides also a precise, quick, and very easy quantification of Hb F and Hb A2, even in the presence of Hb S. It is very suitable for routine investigation of hemoglopinopathies.