Microchromatographic quantitation of hemoglobin A levels in phenotypes of sickle cell-beta(+) thalassemia.

The inheritance of the sickle cell gene in combination with a gene for beta(+) thalassemia results in a spectrum of sickle cell-beta(+) thalassemia syndromes with varying levels of hemoglobin A (HbA). Some severe sickle cell-beta(+) thalassemia syndromes have small amounts of HbA, which may be difficult to quantitate in the presence of fetal hemoglobin. A microcolumn chromatographic method, using 0.5 M Tris-acetic acid developers with varying pH values from 9.0 to 6.0, appears to adequately quantitate small amounts of HbA. This method is relatively simple and cheaper than high-performance liquid chromatography, a major consideration in developing countries.

Microchromatographic quantitation of hemoglobin A levels in phenotypes of sickle cell-beta thalassemia

The inheritance of the sickle cell gene in combination with a gene for á+ thalassemia results in a spectrum of sickle cell-á+ thalassemia syndromes with varying levels of hemoglobin A (HbA). Some severe sickle cell-á+ thalassemia syndrome have small amounts of HbA, which may be difficult to quantitate in the presence of fetal hemoglobin. A microcolumn chromatographic method, using 0.5 M Tris-acetic acid developers with varying pH values from 9.0 to 6.0 appears to adequately quantitate small amounts of HbA. This method is relatively simple and cheaper than high-performance liquid chromatography, a major consideration in developing countries.(AU)

Chromatographic quantitation of HbA levels for distinguishing genotypes of sickle-cell á+ thalassaemia - abstract

Sickle-cell á+ thalassaemia represents a spectrum of conditions, depending on the molecular basis of the á+thalassaemia gene. Different genes manifest different levels of beta chain synthesis and hence varying amounts of HbA. Different á+thalassaemia genes also characterise sickle-cell á+thalassaemia in different groups, several of which occur in Jamaica. Commonest among people of African ancestry are the -29 and -88 substitutions which result in a very mild sickle-cell á+thalassaemia type III associated with high HbA levels (18 - 25 percent). The Indian population manifests more severe genes causing sickle-cell, á+thalassaemia type II with 8 - 15 percent HbA and sickle-cell á+thalassaemia type I with 3 - 5 percent HbA. Estimation of the level of HbA is therefore useful in predicting the probable molecular basis for the á+thalassaemia gene and also the expected clinical course. Measurement of HbA by chromatography in sickle-cell á+ thalassaemia requires adequate separation from both HbS and HbF and anew method is presented which appears to give satisfactory results. The method is based on 0.5M Tris-5 percent acetic acid. Duplicate runs on blood samples from 28 patients gave mean (SD) values of 17.4 (6.7) and 17.2 (6.9) with between-run differences of 0.2 (95 percent C.I.,-0.7, 1.1) p = 0.65; 95 percent of the differences between runs were 4.7 percent or less. HbA measurements with this method did not allow the same grouping as in Greece, which may be due to differences in the two populations or to measurement error. The method is relatively simple and of considerably lower cost than high-performance liquid chromatography (HPLC) (AU)