The human FIP1L1 gene consists of 15 exons occupying a region of 82 kb. The human PDGFRA gene consists of 23 exons spanning a region of 69 kb. Both genes are located on chromosome 4 band q12. Y5422 is a probe mix based on a combination of DNA and PNA technology, and contains two ready-to-use FISH DNA probes and unlabeled PNA blocking probes. The FISH DNA probes are a mixture of a Texas Red-labeled DNA probe (CHIC2) covering 333 kb of the deletion area and a fluorescein-labeled DNA probe covering 571 kb telomeric to the deletion area.