PHENOL EXTRACTION REVISITED - A RAPID METHOD FOR THE ISOLATION AND PRESERVATION OF HUMAN GENOMIC DNA FROM WHOLE-BLOOD

We report a fast and simple DNA isolation method from whole blood. It avoids cell separation and lysis steps and consists of three successiv e solvent extractions and an ethanol precipitation. All the steps are carried out at room temperature. The main advantage of this method is the immediate sample inactivation achieved by mixing the blood sample with Tris-HCl (pH 8.0) saturated phenol, thus minimizing the biohazard involved in the subsequent manipulation of the samples potentially co ntaminated with infectious agents (the procedure has been called SP fo r 'straight phenol'). In addition, extensive field sample collections are facilitated by the fact that the SP procedure can be stopped right after the simple manipulation of mixing the blood sample with the phe nol; neither freezing nor refrigeration of the sample proved to be req uired. At this stage, the nucleases as well as infectious agents are i nactivated and the rest of the protocol can wait to be carried out in the laboratory. In fact, the DNA preparation can be resumed after prol onged storage of the blood-phenol mix (up to 72 days has been checked in our laboratory) at room temperature without affecting the yield. Th e SP protocol may be scaled up, when large quantities of DNA are neede d, or scaled down to smaller volumes, such as fingerprick blood sample s.