A method for analyzing the presence of a PIK3CA mutant allele DNA in a DNA sample, said method comprising the steps of performing an asymmetric and allele specific Polymerase Chain Reaction (PCR) of said mutant allele DNA, and performing a melting analysis of the DNA produced in the PCR, wherein said PCR is carried out by the use of - a mutant allele specific primer complementary to a 3' (three prime) end of a first strand of the mutant allele DNA to be amplified, said mutant allele specific primer comprises a mutation site and a mismatch to corresponding wild type DNA, and - an unlabeled blocking probe that is an oligonucleotide complementary to a wild type sequence of a first strand of wild type DNA corresponding to a first strand of the mutant allele DNA at a corresponding position in which a mutation to be detected is present, said unlabeled blocking probe comprising an additional mismatch to said first strand of the mutant allele DNA besides the mutation site, and which probe is blocked from acting as a primer for DNA synthesis in the PCR reaction, and - a common primer that is complementary to a 3' end of a second strand of the mutant allele DNA to be amplified by the PCR, and wherein said melting analysis is carried out by the use of - a melting probe being a non-labeled probe that is an oligonucleotide that comprises a sequence that is complementary to the wild type allele DNA and overlaps with a sequence of the mutant allele DNA, and - a detectable component for measuring a melting temperature of double-stranded DNA components at least including a double-stranded component of the melting probe bound to an amplified mutant allele DNA strand or wild allele DNA strand, wherein the melting temperature differs between the double-stranded component of the melting probe bound to the amplified mutant allele strand and the melting probe bound to the amplified the wild allele strand. - a mutant allele specific primer complementary to a 3' (three prime) end of a first strand of the mutant allele DNA to be amplified, said mutant allele specific primer comprises a mutation site and a mismatch to corresponding wild type DNA, and - an unlabeled blocking probe that is an oligonucleotide complementary to a wild type sequence of a first strand of wild type DNA corresponding to a first strand of the mutant allele DNA at a corresponding position in which a mutation to be detected is present, said unlabeled blocking probe comprising an additional mismatch to said first strand of the mutant allele DNA besides the mutation site, and which probe is blocked from acting as a primer for DNA synthesis in the PCR reaction, and - a common primer that is complementary to a 3' end of a second strand of the mutant allele DNA to be amplified by the PCR, and wherein said melting analysis is carried out by the use of - a melting probe being a non-labeled probe that is an oligonucleotide that comprises a sequence that is complementary to the wild type allele DNA and overlaps with a sequence of the mutant allele DNA, and - a detectable component for measuring a melting temperature of double-stranded DNA components at least including a double-stranded component of the melting probe bound to an amplified mutant allele DNA strand or wild allele DNA strand, wherein the melting temperature differs between the double-stranded component of the melting probe bound to the amplified mutant allele strand and the melting probe bound to the amplified the wild allele strand. <EOS>