Agarose gel electrophoresis of the URO-synthase RT-PCR products amplifed from total lymphoblast RNA from a normal individual (N) and the CEP patient (P). RT-PCR 1 used primers that amplified a normal 416-bp product from exon 6 to exon 10 and RT-PCR 2 used primers that amplified a 223-bp product from exon 8 to exon 10. Note that the RT-PCR products of the normal individual and the CEP patient were the same size.