Control and IVS4 mutant FGA constructs and direct sequencing of RT-PCR products.

(A) Control and mutant constructs used. The genomic FGAfragments contain the complete coding sequences from exons 1 to 4, complete introns 1 to 4, and part of exon 5. All the natural splice sites are therefore present in the insert. The oligonucleotides used for RT-PCR analysis are indicated by the white arrows. (B) Sequences of the uncloned RT-PCR products from COS-7 cells transfected with the control and IVS4 + 1 G→T mutant constructs. The IVS4 + 1 G→T donor site mutation leads to a 4-bp insertion (TTAA) between exons 4 and 5, due to utilization of a cryptic donor site situated 4-bp downstream.