Is cellulose acetate electrophoresis a suitable technique for detection of Hb Bart's at birth?

Abstract

Symptomatic alpha-thalassemia (alpha-thal) as found in South-East Asia is uncommon in India. However, the presence of Hb Bart's in cord blood samples has been reported from different parts of India and the prevalence of alpha-thal has ranged from 0.5 to 18% by different electrophoretic techniques. The methodology utilised has ranged from paper electrophoresis to isoelectric focussing (IEF). We screened 798 cord bloods for the presence of Hb Bart's by cellulose acetate electrophoresis and found a prevalence rate of alpha-thal of 15.3% in a heterogenous population in Bombay. A comparison of four different electrophoretic techniques for detection of Hb Bart's in 138 neonates showed that cellulose acetate and starch gel electrophoresis were by and large comparable and only a little less sensitive than IEF. Paper electrophoresis used at many centers in India was most insensitive. As alpha-genotyping is not possible at most centers in the country, it is suggested that a simple cellulose acetate electrophoresis would be the method of choice for screening neonates for alpha-thal in India. As a part of our follow-up study, alpha-genotyping was done by Southern blot hybridization in 24 cases who had shown variable levels of Hb Bart's at birth. The rightward deletion (-alpha3.7/) either in a heterozygous or homozygous condition was the only gene defect encountered in this preliminary study. However, 7 of 24 cases (29.17%) showed no correlation between Hb Bart's level and alpha-genotypes.