Analysis of the splicing pattern obtained with the minigenes. A- The splicing K7 consists of exon 1 of β-globin and its downstream intronic sequences joined to β-globin exon 3 and its upstream intronic sequences. Exon 9, with or without the Q279R mutation was inserted in K7 at the intronic junction. HeLa cells were transiently transfected with both constructs, the wild-type Q279Q-K7 and Q279R-containing Q279R-K7. After 24 hours, cells were harvested and the splicing pattern of each minigene was examined by RT-PCR analysis of the transcripts. Exons are represented by boxes and introns by lines. The primers used for RT-PCR are indicated at each end of the splicing K7. B- Total RNA extracted from transfected HeLa cells was amplified with HG1S and HG3AS. Plasmidic DNA Q279Q-K7 and Q279R-K7 (pDNA) were also amplified as a control. The band obtained for Q279Q-K7 transfected cells (RT+) is of expected size, in contrast to the band obtained in the case of Q279R-K7 (RT+) transfected cells, which is of lower molecular weight. RT- serves as a negative control: the reverse transcription reaction was performed without any enzyme. In the two RT- fractions, the amplification of about 900-bp is due to plasmidic DNA contamination.