The ddPLEX ESR1 Mutation Detection Kit quantitatively interrogates seven key ESR1 variants across three exons: exon 5 (E380Q), exon 7 (S463P) and exon 8 (L536R, Y537C, Y537S, Y537N and D538G), and their wild-type counterparts. Used for the detection, discrimination, and quantification of key ESR1 mutations for breast cancer research, from cfDNA in plasma and/or DNA in formalin-fixed paraffin embedded (FFPE) tissue samples.