Base substitution at position -88 in a β-thalassemic globin gene. Further evidence for the role of distal promoter element ACACCC

A base substitution (C → T) at position -88 relative to the cap site was identified in the β-globin gene cloned from an individual with a mild form of β-thalassemia. This nucleotide change lies in the sequence ACACCC proposed as a distal promoter element. Transient expression of the mutant gene in HeLa cells revealed a modest deficit in β-globin mRNA production. RNA processing was normal. The -88 β-thalassemia mutation lends further support for the in vivo role of the distal element in transcription.