Amplification of G6PD by multiplex RT-PCR and analyzed by electrophoresis on 2% agarose gels. A. Representative examples of amplification products from RNA extracted from ten year old FFPE, samples 6 and 12; B. representative examples of amplification products from RNA extracted from recently archived months old FFPE, samples 15, 23, 22, 24. RNA fragments extracted from all 28 of the ten year old and months old samples were of sufficient size to generate shorter amplicons of G6PD 67 bp and 151 bp, visible on the gel; the 242 bp amplicon was visualized in none of the 10 year old samples and only six of 14 (43%) of the months old samples. All non-visualizing amplification products in the multiplex experiments were confirmed by PCR with single primer sets. M = marker (DNA ladder).