β-Like globin RNA sequences in hemoglobin Lepore disease

A Southern Italian patient homozygous for hemoglobin Lepore disease synthesizes approximately 3% Lopore δβ-globin chains (relative to α chains) in the reticulocytes. Measurement of β-like RNA squences by hydridization to complementary DNA specific for β-globin demonstrates a low level (1-2% relative to α sequences) of these sequences in cytoplasmic RNA from reticulocytes or spleen cells, suggesting that the Lepore gene is expressed into mRNA at a lower extent than normal α or β genes; the comparison with the level of β-like sequences found in nuclear RNA (6-8%) further supports this conclusion and indicates, in addition, that Lepore RNA might be degraded at a faster rate than normal. 2-3% β-like sequences are found in nuclear RNA in three cases of homozygous β ⁰-thalassemia, setting the highest possible estimate for the δ-RNA level; this figure suggests that the 'δ-promotor'-dependent Lepore δβ gene is somehow more actively expressed than the δ gene.