Figure 2

Detection of PIK3CA mutations. Chromatogram tracing for exon 20 sequences encoding the catalytic kinase domain in primary neuroblastomas #1070 (A) and #1218 (B). Sequences demonstrate heterozygous alterations in these tumor samples as depicted by the arrows, with the amino acid change for #1070 being GAG (glutamic acid) to GAT (representing GAU, aspartic acid). Alterations were confirmed bi-directionally and in replicate sequencing. T, tumor DNA sequence; N, normal (or constitutional) DNA sequence. Note the tumor-specific (somatic) mutation in #1070, whereas the alteration in the 3'-UTR in #1218 is present in both tumor and constitutional DNA and likely represents a rare polymorphic variant.