Laboratory diagnosis of homozygous alpha thalassaemia

Alpha-thalassaemia is one of the most prevalent haemoglobinopathies in the world. The molecular basis of the condition is mainly due to deletion of one or more alpha genes and occasional point mutations. The diagnosis and treatment of microcytic hypochromic anaemia is at times a problematic medical issue in Ghana due to co-existence of a-thalassaemia traits and iron deficiency anaemia (IDA) since there is no routine laboratory procedure for the diagnosis of the former.

To identify the alpha thalassaemias and determine a simple laboratory method of differentiating them from other causes of microcytic hypochromic, anaemia.

Venous blood samples of random 216 adult OPD patients at the Central Laboratory of Korle-Bu Hospital were taken for full blood count, iron studies, PCR and restriction enzyme analysis to tag -a3.7-thalassaemia variants.

Of the 200 accepted subjects, 114 (57.0%) were -a/aa, 11 (5.5%) were -a/-a and 75(37.5%) áá/áá. Differences among the entire red cell indices and serum iron measurements between -a/-a and aa/aa, and-a/-a and -a/-aa were found to be statistically significant (P<0.05 in each case) and consistent with previous studies, but there were no significant (P>0.05) differences between -a/aa and aa/aa RBC parameters. However, selective analysis based on Hb<13.0 g/dl for males and <12.0 g/dl for females indicated that combination of RBC indices with iron studies can be used to differentiate -a/-a from IDA. Calculation of RBC/PCV ratios of anaemic aa/aa, and -a/-a was yet another tool as the latter was found to have higher ratio.