Chromatographic analysis of Hb S for the diagnosis of various sickle cell disorders in Pakistan.

Sickle cell disease remains a relatively obscure theme in research on haemoglobinopathies in Pakistan. Limited data is available regarding its prevalence in the country. The objective of our study was not only to estimate the frequency of different sickle cell diseases but also to provide quantitative estimation of haemoglobin S and other haemoglobin variants using an automated high-performance liquid chromatography (HPLC) system. For this purpose, we retrospectively evaluated the results of HPLC performed on all patients with suspected haemoglobinopathies during the years 2005 and 2006. Information derived from various sources was used to identify a particular genotype by analysing each sample containing Hb S with respect to haemoglobin, red cell indices and levels of various associated haemoglobin variants. Analysis of 15,699 samples identified 302 patients with Hb S (1.92%). The genotypes identified included Sbeta(0) (46.7%), SS (19.2%), SA (11.6%), Sbeta(+) (8.6%) and SD (2.3%). Thirty-five cases could not be categorised and were labelled 'unclassified'. Majority of the patients (62.3%) were below the age of 18 years. Balochistan, which is the largest province based on the area, yielded the highest number of patients (n = 140). In the Sbeta(0) group, the mean haemoglobin and Hb S were lower in children compared to adults (p value of 0.001 and 0.016, respectively). We conclude that sickle cell disorders are prevalent in Pakistan to a significant extent, being concentrated in certain areas of the country. We present the first report of various haemoglobin S genotypes from our population. It is hoped that it will act as a database to characterise the same for our population.