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DNA Extraction Method
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DNA is extracted from whole blood or cell pellets using the Gentra Puregene DNA Isolation Kit according to the manufacturer's instructions. The extraction is based on a modified salt precipitation method. DNA extraction from tissue can be performed using either the DNEasy kit (Qiagen) if only DNA is needed, or Trizol (Invitrogen) when study design requires extraction of RNA and DNA from the same tissue sample.

Quantitation / Qualitation
Once DNA is isolated, the DNA quantity and quality is checked using a spectrophotometer. The concentration and purity is measured by reading the Absorbance at 260 nm and 280 nm wavelengths. The expected range of high quality DNA preparations based on the A260/A280 nm wavelength ratio should be 1.7-2.0. Should the ratio deviate from this range, it may indicate protein or RNA contamination, and the sample would require repurification.

Sample Storage
Following extraction the DNA is stored at -20°C in DNA Hydration Solution, which is supplied with the Gentra Puregene DNA Isolation Kit.

The Investigator is provided with a spreadsheet containing the Absorbance at 260 nm and 280 nm wavelengths, A260/A280 nm wavelength ratio, the DNA concentration, hydration volume and the total yield of DNA for each sample.