A SIMPLE METHOD FOR EXTRACTING DNA FROM OLD SKELETAL MATERIAL

Extraction of DNA from old skeletal material is of great importance in the identification of human remains, but is particularly difficult be cause the methods currently employed, especially those using phenol/ch loroform, are not always satisfactory. A simple technique based on the removal of non-nucleic acid material by salting out (precipitation) w ith saturated sodium acetate is described; the presence of DNA in the extract being confirmed by amplification of selected sequences of the HLA-DRB1 gene using the polymerase chain reaction (PCR). The method wa s applied to fresh bone (five femoral heads and six vertebral bodies) and to bone from two forensic cases, 3 and 9 months post-mortem, respe ctively. Parallel extractions using the phenol/chloroform technique we re performed on all samples in order to compare the efficiency of the two methods. Using sodium acetate precipitation, amplifiable DNA was c onsistently extracted from fresh bone, as well as from the two forensi c cases. With the phenol/chloroform method, amplification was successf ul in only 7 out of 11 instances with the fresh bone samples and faile d in both forensic cases. The studies also showed that an effective wa y of removing PCR inhibitors is to subject the extract to agarose gel electrophoresis, isolate the high molecular weight area and re-extract the DNA from the gel by boiling. It was concluded that the sodium ace tate method is a valid alternative to established techniques for extra cting DNA from bone and that it offers the advantages of being simple, quick, inexpensive and avoids using hazardous reagents.