Interphase FISH. Deletion of 1 of the CHIC2 alleles results in 1 orange and 2 green signals in interphase nuclei (FISH strategy 1). However, this 2-color FISH strategy using CHIC2/FGFR3 probe set would appear normal if CHIC2 was translocated rather than deleted. In such cases, the abnormality will be detected by the second FISH strategy where the insertional translocation involving excision of the CHIC2 locus results in a FISH signal pattern of 3 fusions using the FIP1L1/PDGFRA probe set.