Table 1.
Summary of biological specimen used for DNA isolation with results.
| Source | Number | Method | Storage at −80°C | Adequate DNA yielda | Adequate DNA qualityb | DNA degradationc | Successful PCR amplificationd |
|---|---|---|---|---|---|---|---|
| Blood | 100 | Phenol extraction; Qiagen | Mixede (0–10 years) | 95% | 90% | 10% | 90% |
| Lymphoblast | 100 | Phenol extraction; Qiagen | Mixede (0–10 years) | 95% | 90% | 10% | 90% |
| Saliva | 30 | Oragene | Mixed (0–5 years) | 90% | 90% | 20% | 90% |
| Buccal | 84 | Epicenter (MasterPure) | 4–6 months | 90% | 50% | 42% | 70% |
| Buccal | 27 | Qiagen | 4–6 months | 80% | 70% | 74% | 50% |
| Stored plasma | 38 | Qiagen | 4–6 years | 80% | 45% | 90% | 20% |
| Fresh plasma | 4 | Qiagen | Fresh/not stored | 75% | 50% | 50% | 50% |
a
Estimated at ≥ 1 μg of DNA per extraction.
b
OD 260/280 ratio between 1.6 and 2.1.
c
Based on gel electrophoresis with visible intact DNA (i.e., 8000–10,000 bp) with ethidium bromide stain.
d
PCR amplification success is correlated with the size of the PCR fragment generated (e.g., larger PCR fragments require more intact DNA).
e
There were no obvious differences in the quality of DNA collected using the two DNA extraction methods in blood or lymphoblast specimens or differences related to short-term (0–5 years) vs. long-term (6–10 years) storage at −80°C.