Figure_3.tif (468.56 kB)

PIK3CA hotspot mutations in Merkel cell carcinoma.

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posted on 2013-02-20, 08:52 authored by Christian Hafner, Roland Houben, Anne Baeurle, Cathrin Ritter, David Schrama, Michael Landthaler, Juergen C. Becker

(a) The heterozygous p.E542K (c.G1624A) PIK3CA hotspot mutation was detected in sample no. 27 by direct sequencing (left) and a PIK3CA SNaPshot® assay (right) covering the most frequent hotspot PIK3CA mutations. The number of the wildtype codons is indicated above the peaks in the SNaPshot® assay. In brief, the SNaPshot® assay comprises a multiplex PCR for exons 9 and 20 of PIK3CA, followed by extension of 4 primers specific for the most frequent PIK3CA hotspot mutation loci. Because fluorescent dideoxynucleotides are used for this primer extension step, only one peak appears at the base position with the potential mutation. The color of the peak allows discrimination of wildtype and mutated alleles. (b) The heterozygous p.E545Q (c.G1633C) PIK3CA hotspot mutation was detected in sample no. 24 by direct sequencing (left) and a PIK3CA SNaPshot® assay (right) covering the most frequent hotspot PIK3CA mutations. The number of the respective wildtype codon is indicated above the peaks in the SNaPshot® assay.