Abstract
Using a polymerase chain reaction procedure we have identified the 3.7 kb α-thalassemia-2 deletion in the DNA that was isolated from slides of blood smears stained with Wright's stain some 20 years ago. Details about the procedure are presented. The success of this approach depends entirely on the amount of DNA that could be isolated; thick smears always gave good data provided they were not covered with immersion oil. The success rate in this study was 45%.