Exon 19 deletions encountered in triple negative breast cancers. Diagrams A to D show nucleotide sequences of EGFR gene in triple negative breast tumour specimens with heterozygous in-frame deletions within Exon 19 tyrosine kinase domain (double peaks). Tracings in both (A, C) sense and (B, D) antisense directions. The wildtype sequence is shown in capital letters, while the deleted mutant sequence is in lowercase letters. Deleted sequence is highlighted in red capital letters. (A, B) 24 bp deleted region of EGFR gene leading to removal of SPKANKEI at codons 752 to 759. (C, D) 15 bp deleted region of EGFR resulting in deletion of ELREA at codons 746 to 750.