RT-PCR analysis of platelet GPIIb-mRNA. (Top panel) Total RNA from the proband and her mother was reverse-transcribed and used as template for the PCR amplification of a 1,190-bp fragment encompassing exons 20 to 30 of GPIIb as described in Materials and Methods. Direct DNA sequencing of the amplification products was performed in a model ABIprism 377 DNA sequencer (Perkin-Elmer Cetus). (Bottom panel) (A) 779-bp DNA fragments encompassing exons 5 to 13 of GPIIb were amplified using as template reverse-transcribed platelet RNA as described in Materials and Methods. (B) Portions of the amplification products were reamplified using a sense primer complementary to sequences of intron 5 of GPIIb. (C) and (D) depict the hybridization analysis of the PCR products shown in (A) and (B), using a GPIIb probe lacking the oligonucleotide sequences used for amplification. N, PCR products from normal platelet RNA.