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Is cellulose acetate electrophoresis a suitable technique for detection of Hb Bart's at birth?
Insights
Alpha-thalassemia (alpha-thal) screening in India is crucial. Cellulose acetate electrophoresis is recommended for detecting Hb Bart
Area of Science:
- Genetics
- Hematology
Background:
- Symptomatic alpha-thalassemia is rare in India.
- Hb Bart's presence in cord blood is documented across India.
- Alpha-thalassemia prevalence varies (0.5-18%) based on electrophoretic methods.
Purpose of the Study:
- Determine alpha-thalassemia prevalence in a heterogeneous Indian population.
- Compare the sensitivity of different electrophoretic techniques for Hb Bart's detection.
- Identify the most suitable screening method for neonates in India.
Main Methods:
- Screened 798 cord blood samples using cellulose acetate electrophoresis.
- Compared four electrophoretic techniques (cellulose acetate, starch gel, IEF, paper) in 138 neonates.
- Performed alpha-genotyping via Southern blot hybridization in 24 cases.
Main Results:
- Identified a 15.3% prevalence of alpha-thalassemia in Bombay.
- Cellulose acetate and starch gel electrophoresis showed comparable sensitivity, slightly less than IEF.
- Paper electrophoresis was the least sensitive method.
- The rightward deletion (-alpha3.7/) was the sole gene defect found.
- A significant portion (29.17%) of cases showed no correlation between Hb Bart's levels and alpha-genotypes.
Conclusions:
- Cellulose acetate electrophoresis is a practical and effective method for neonatal alpha-thalassemia screening in India.
- Further research is needed to understand the discrepancy between Hb Bart's levels and alpha-genotypes.
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.