Abstract: The present invention relates to a method for detecting point mutation(s) and/or large scale alteration(s) relative to at least one nucleic acid fragment said method comprising at least the steps of providing a sample liable to contain said nucleic acid fragment and at least a second nucleic acid fragment acting as a quantitative reference, subjecting said fragments to suitable conditions for obtaining a product containing homoduplexes and possible heteroduplexes, conducting on said product an analytical method suitable for obtaining at least signal(s) discriminating the existing duplex form(s) of the first nucleic acid fragment and relative quantitative data concerning said first nucleic acid fragment The invention further relates to the use of this method in the diagnosis of predisposition to genetic diseases and cancers and in the diagnosis and prognosis of said diseases and cancers, like human breast cancer.