The EGFR (epidermal growth factor receptor) gene located on chromosome 7p11.2 spans approximately 188 kb and contains 28 exons. EGFR/CEN-7 FISH Probe Mix detects the copy number of the EGFR gene using the chromosome 7 centromere region as a reference. Y5500 is based on a combination of PNA and DNA technology, and contains a 196 kb Texas Red-labeled DNA probe covering the full EGFR gene and fluorescein-labeled PNA probes targeted at the centromeric region of chromosome 7. The probe mix also contains unlabeled PNA oligos directed towards repetitive sequences in the genome to diminish unspecific staining.