Table 1

PCR amplification of β-globin gene fragments from DNA from fresh buccal cell samples collected on treated cards

Fresh samplesanSuccessful PCR amplification n (%)
268 bp536 bp989 bp
DNA extract never frozen
Taq polymerase5251 (98.1)50 (96.1)c47 (90.4)
Taq polymerase or AmpliTaq Goldb5251 (98.1)51 (98.1)48 (92.3)
DNA extract frozen at−20°C for 1 wk
Taq polymerase52N/Ad46 (88.5)cN/A
Taq polymerase or AmpliTaq Goldb52N/A 51 (98.1)N/A
  • a All fresh samples were stored at room temperature for 5 days, at which time DNA was extracted, and the DNA extract was stored at 4°C. Never frozen DNA extract was maintained at 4°C before PCR, whereas the DNA extract was stored at −20°C for 1 week for experiments on frozen DNA extract.

  • b AmpliTaq Gold used for samples that did not amplify by use of Taq polymerase.

  • c P = 0.13, McNemar’s exact test; frozen DNA versus never frozen DNA amplified by Taq polymerase.

  • d N/A, not applicable.