Amplification of platelet RNA by RT-PCR. (A) Platelet RNA from a control subject (top tracing) and the patient (lower tracing) were subjected to RT-PCR using primers flanking exons 3 to 6 of CBFA2. The sequence shows a loss of 13 nt (796-808) in the patient in the Runt domain. (B) Amplification of platelet RNA from the patient (P), and the patient's brother (B), mother (M), and sister (S), and of patient's neutrophil RNA (P-Neu) by RT-PCR using a forward primer in exon 3 and reverse primer in exon 4. Two transcripts of 179 bp (expected size) and 169 bp are noted in the patient with only a single 179-bp transcript in the family members.