New protocol for DNA extraction of stool

Present methods for DNA isolation of stool have various limitations such as the amount of stool used, the requirement of lavage fluids or the use of f resh stool. In this paper; a new method is described for the isolation of h uman nucleic acids from stool, which is independent from the moment of coll ection. Fecal samples as dry as possible were collected from 75 patients; t wo grams of stool were mixed with a lysis buffer containing phenol. DNA yie lds of crude stool were variable and ranged from 9-1686 mu g/g of feces. Wi th dot blots in 9 of the 75 cases, the human DNA was identified and ranged from 0.06%-46%. In the remaining 66 cases, human genomic DNA was detected b y nested PCR, using human K-ras gene amplification as an example. Amplifica tion products were confirmed for human K-ras with the exonuclease-amplifica tion coupled capture technique (EXACCT). In conclusion, the developed DNA i solation method can be used for the study of large numbers of stool samples , is independent of the age or method of stool collection and is suitable f or large-scale screening studies.