Transcriptional and Post‐transcriptional Defects in β0‐Thalassaemia

Abstract
Complementary DNA enriched in sequences hybridizing to β‐globin mRNA was prepared with viral RNA‐dependent DNA polymerase and used as a probe for the presence of β‐globin mRNA in nuclear and cytoplasmic RNA from two Italian patients with β°‐thalassaemia. In both cases the β‐globin gene was present and cytoplasmic mRNAβ was absent; however, one case appeared to transcribe mRNAβ and to fail to process it, while the other appeared transcriptionally defective. Evidence is also presented that the low levels of hybridization usually found at high RNA/cDNAβ ratios in β°‐thalassaemia are due to δ‐globin mRNA; the melting profile of the hybrid formed has been determined and a low melting temperature relative to mRNAβ· cDNAβ demonstrated.