Exchange of positions of double strands in EGFR exon 19, accompanied by gene inversions. Diagrams A and B show nucleotide sequences of EGFR exon 19 gene in triple negative breast tumour specimens with heterozygous gene inversions of the complementary strand (double peaks). Tracings in both (A) sense and (B) antisense directions. The wild type sequence is shown in black capital letters, while the mutant sequence is in red lowercase letters. The complementary sequence of the mutant strand corresponds exactly to the wild type sequence and the orientation is reversed. Note only a segment of the sequencing diagrams (reading sequence towards the end) of the forward and reverse sequence is shown to demonstrate that the whole portion of exon 19 gene is inverted with exchange of the complementary strands.