Patent ID: 7175982

Claim:
A method for characterising nucleic acid molecules, which comprises the steps of: i) introducing a modified base which is a substrate for a DNA glycosylase into a DNA molecule by enzymatic extension of the molecule on a template nucleic acid; ii) excising the modified base by means of said DNA glycosylase so as to generate an abasic site; iii) cleaving the DNA at the abasic site so as to generate and release an extendible upstream DNA fragment having a 3′ hydroxyl terminus, wherein the sequence of the extendible fragment is determined by the sequence of the template nucleic acid; and iv) incubating the released extendible upstream DNA fragment in the presence of an enzyme allowing for extension thereof and a selected template nucleic acid, which has partial or full sequence complementarity to said upstream DNA fragment and analysing resultant fragment(s) to detect the presence or absence of a mutation.